
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            WASHINGTON, D.C.  20460
                                                                      OFFICE OF
                                                            CHEMICAL SAFETY AND
\* MERGEFORMAT
                                                           POLLUTION PREVENTION

MEMORANDUM

Date:	 Aug 29, 2016

Subject:	Diquat Dibromide.  Revised Occupational and Residential Exposure Assessment for Registration Review.

	
PC Code:  032201
DP Barcode:  D434562
Decision Nos.: 512662
Registration No.: Multiple Registrations
Petition Nos.:  NA
Regulatory Action:  Registration Review Risk Assessment
Risk Assessment Type:  Single Chemical
Case No.:  0288
TXR No.:  N/A
CAS No.: 85-00-7, 2764-72-9 (cation)
MRID No.: N/A
40 CFR:  §180.226
	


FROM:	James Miller, Environmental Scientist
		Health Effects Division/Risk Assessment Branch 1 (HED; 7509P)
	
THRU:           Kelly Lowe, Acting Branch Chief
	Risk Assessment Branch I
	HED (7509P)

	Joshua Godshall, Biologist
	Exposure Science Advisory Committee (ExpoSAC) / HED

TO:		Bonnie Adler 
		Pesticide Re-evaluation Division (PRD; 7508P)

		










Introduction		
As part of Registration Review, the Pesticide Re-evaluation Division (PRD) of OPP has requested that HED evaluate the hazard and exposure data and conduct occupational and residential exposure assessments, as needed, to estimate the risk to human health that will result from the currently registered uses of pesticides.  This memorandum serves as HED's Registration Review risk assessment of the occupational and residential handler and post-application exposure and risk from the currently registered uses of diquat dibromide.  

It is HED policy to use the best available data to assess exposure. Several sources of generic data were used in this assessment as surrogate data in the absence of chemical-specific data, including:  Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1); the Outdoor Residential Exposure Task Force (ORETF) database, the Agricultural Handler Exposure Task Force (AHETF) database, the November 2015 Aquatic Use Standard Operating Procedure (SOP), and the Agricultural Reentry Task Force (ARTF) database. Some of these data are proprietary, and subject to the data protection provisions of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). 

This revised document supersedes previous versions and includes (1) updates to the assumptions for aquatic uses to reflect information received from the Army Corps of Engineers.

Note:  This revised memorandum was reviewed on 8/4/2016.
























                                       
                               Table of Contents

1.0	Executive Summary	4
2.0	Risk Assessment Conclusions and Recommendations	7
  2.1	Summary of Risk Estimates	7
  2.2	Label Recommendations from Occupational Assessment	7
  2.3	Label Recommendations from Residential Assessment	8
  2.4	Data Deficiencies and Requirements	8
3.0	Hazard Characterization	9
4.0	Use Profile	13
5.0	Residential Exposure and Risk Estimates	15
  5.1	Residential Handler Exposure/Risk Estimates	16
  5.2	Residential Post-application Exposure/Risk Estimates	18
  5.3 	Residential Risk Estimates for Use in Aggregate Assessment	19
  5.4	Spray Drift	20
  5.5	Residential Bystander Post-Application Inhalation Exposure	21
6.0	Occupational Exposure and Risk Estimates	21
  6.1	Occupational Handler Exposure/Risk Estimates	21
  6.2	Occupational Post-application Exposure/Risk Estimates	30
    6.2.1	Occupational Post-application Inhalation Exposure/Risk Estimates	30
    6.2.2	Occupational Post-application Dermal Exposure/Risk Estimates.....................31
Appendix A. Summary of Occupational and Residential Non-cancer Algorithms..................33
Appendix B. Summary of Label Directions concerning Aquatic Uses...............................59
References.....................................................................................................60






















1.0	Executive Summary

The active ingredient of diquat dibromide, 6, 7-dihydropyrido(1,2-a:2',1,-c) pyrazinediium dibromide, is a non-selective contact herbicide, desiccant and plant growth regulator. The oxidative activity, which occurs subsequent to formation of the oxygen radicals, rapidly destroys plant cell membranes. 

Use Profile
Diquat dibromide is used as an herbicide/algaecide, and is formulated as a soluble concentrate (SC) and a ready to use liquid (RTU) intended for use on aquatic, terrestrial, and non-terrestrial weeds, and as a pre-harvest desiccant, post-harvest defoliant on various crops and on resistant dormant turf (Bermuda and Zoysia grass).  Diquat dibromide is applied by direct pouring, handheld or mechanical sprayer, injection below the water surface and directly into sewer pipes, aircraft, and ground equipment. Maximum application rates vary according to use description.  Maximum application rates for occupational use sites range from 0.25 lb ai/acre to 0.5 lb ai/acre for terrestrial, non-crop terrestrial, and farmland uses. For aquatic uses, the maximum rate for aerial application is 4 lb ai/acre-ft, while an application rate of 0.04 lb ai/gal was used for handheld equipment to lakes and ponds.  Maximum application rates for residential use sites range from 0.5 lb ai/acre to 0.01 lb ai/gal for gardens, trees, and turf (resistant dormant Bermuda and Zoysia) and up to 0.000092 lb ai/ft [2] for aquatic uses such as backyard ponds. 

Exposure Profile
Occupational:  There is a potential for occupational exposure associated with handler (i.e., mixing, loading and applying) activities for the registered uses.  Based on application rates and label information, occupational exposure to diquat dibromide is expected to occur for short-(1 to 30 days) and intermediate-term (1 to 6 months) durations.  Chronic exposures are not expected and were not assessed.  Occupational post-application exposure is anticipated for the registered golf course use.  For the other registered uses (e.g., ground directed desiccant and the post-harvest defoliant), HED does not believes significant exposure will occur, and the handler exposures being assessed within this document for those uses will be protective of any post-application exposure.  Based on the Agency's current practices, a quantitative non-cancer occupational post-application inhalation exposure assessment was not performed for diquat dibromide at this time.  If new policies or procedures are put into place, the Agency may revisit the need for a quantitative occupational post-application inhalation exposure assessment for diquat dibromide. Furthermore, a spray drift assessment was conducted but not included in this assessment, whereas residential turf application exposure scenarios are protective. See section 5.4 for details.

The diquat dibromide product labels direct mixers, loaders, applicators and other handlers to wear long-sleeved shirt and long pants, coveralls, shoes plus socks, chemical-resistant gloves and protective eyewear such as goggles or face shield, chemical-resistant headgear for overhead exposure, chemical resistant apron when cleaning equipment and no respirator. However, for sewer treatments, product labels include a respirator for the exposure scenarios listed above. The restricted-entry interval (REI) is 24 hours for all registered products.

Residential:  There is a potential for residential exposure associated with handler (i.e., mixing, loading and applying and ready to use products) activities for the registered uses.  Based on application rates and label information, residential exposure to diquat dibromide is expected to occur for a short-term (1 to 30 days) duration.  Chronic exposures are not expected and were not assessed.  Short-term dermal post-application exposure is anticipated for adults and children performing activities on treated turf, in treated gardens, and in aquatic areas.  Inhalation and incidental ingestion exposure is anticipated for adults and children swimming in aquatic areas.  For children (1 to <2 years old), incidental oral [Hand to Mount (HTM), Object to Mouth (OTM), and Soil Ingestion (SI)] exposure is also anticipated based on the turf use.   

Hazard Profile
Diquat dibromide is classified as Acute Toxicity Categories II or III via the oral, dermal, and inhalation routes.  Diquat dibromide is not an acute skin irritant (Toxicity Category IV) nor a dermal sensitizer, but it is considered a moderate-to-severe eye irritant (Toxicity Category II).

The following points of departure (PODs) have been chosen for diquat dibromide: 1) a no observed adverse effect level (NOAEL) of 3 mg/kg/day from a developmental toxicity study in rabbits for short-or intermediate-term dermal and incidental oral exposures; 2) a NOAEL of 0.1 ug/L from a subchronic inhalation toxicity study in rats; corresponding to human equivalent concentrations (HECs) of 4.4x10[-5] mg/L for occupational worker exposure and 5.9x10[-5] mg/L for residential handler and post-application exposure.  Subsequent human equivalent dose values of 0.0042 mg/kg/day and 0.0014 mg/kg/day were calculated for these occupational and residential exposure assessments, respectively.

The body weight appropriate for adult dermal and inhalation assessments is 80 kg, since the PODs and effects are not developmental/fetal effects and are not specific to females. Body weights of 57, 32, and 11 kilograms were used for the different child life-stages associated with residential post-application, incidental oral, and spray drift exposure scenarios.  A 0.3% dermal absorption factor was applied.  Diquat dibromide is classified as not likely to be carcinogenic to humans;" therefore, a cancer assessment was not conducted.

HED's level of concern (LOC) for non-cancer risks (i.e., level of concern for MOEs or Margins of Exposure) is defined by the uncertainty factors. Both residential and occupational dermal and incidental oral exposure scenarios utilized a 10x uncertainty factor for human to human extrapolation (UFH) and a 10x for animal to human extrapolation (UFA), for a total LOC of 100. Both residential and occupational inhalation exposure scenarios utilized a 10x uncertainty factor for human to human extrapolation (UFH) and a 3x for animal to human extrapolation (UFA), for a total LOC of 30.

Residential Exposure/Risk:
For most short-term residential handler and post-application exposure scenarios, there are no risk estimates of concern associated with the use of diquat dibromide (i.e., MOEs >= 100 for dermal or incidental oral, and MOEs >= 30 for inhalation).  However, the following inhalation exposure scenario presented risks of concern:


Inhalation
 Backpack sprayer applications to gardens, trees and turf (lawns) and aquatic uses for recreational/backyard ponds

Spray drift:  
The existing turf post-application assessment is considered protective of spray drift exposure based on the maximum application rate on crops and the existing turf application rates; therefore, a separate quantitative spray drift assessment was not conducted.  Dermal and incidental oral post-application MOEs for turf were not of concern (MOEs >= 100). See section 5.4 for details. 

Occupational Handler Exposure/Risk:
There are no dermal short- or intermediate-term occupational risk estimates of concern at baseline (i.e., no gloves) associated with the existing uses of diquat dibromide (i.e., MOEs >= 100).  Some occupational scenarios reached acceptable inhalation MOEs at baseline (i.e., no respirator); however, several exposure scenarios presented risk estimates of concern (MOE < 30) at baseline.  

The following scenarios reached acceptable MOEs with the addition of a PF5 respirator:
 Mixing/Loading for aerial applications to typical field crops,
 Mixing/Loading for boom sprayer applications to aquatic areas (surface weeds),
 Mixing/Loading for groundboom applications to high acreage crops, 
 Applying with groundboom to typical and high acreage field crops.
 Mixing/Loading/Applying for a backpack sprayer to rights of way and landscaping, turf/athletic fields, structural and industrial/commercial areas,
 Mixing/Loading/Applying for a mechanically-pressurized hand-wand application for the use on greenhouse ornamentals, roses, cut flowers landscaping turf, industrial and commercial areas including foundations, structural and aquatic areas.

The following scenarios reached acceptable MOEs with the addition of a PF10 respirator:
 Applying boom sprayer to aquatic areas (surface weeds),
  Applying mechanically pressurized handgun to rights of way, utilities, railroad and roadways,
 Flagger for typical and high acreage field crops, and
 Mixing/Loading/Applying for a mechanically-pressurized hand-gun application for use in orchards (in and around trees), industrial/commercial areas, and typical field crops.

The following scenarios do not reach acceptable MOEs even with maximum PPE and EC:
 Mixing/Loading for aerial applications to high acreage crops and aquatic areas, 
 Mixer/Loader for boom sprayer applications to aquatic areas (submersed weeds) and
 Mixing/Loading/Applying for a mechanically-pressurized hand-gun application in greenhouses.

Occupational Post-application Exposure/Risk:
An occupational post-application assessment was conducted for exposure due to golf course maintenance activities; there were no risk estimates of concern (i.e., MOEs >= 100).  An assessment was not conducted for pre-, and post-harvest desiccant/defoliant burn down uses, turf applications to industrial areas nor for aquatic uses, whereas commercial workers associated with these activities are not expected to be in these areas post treatment. 

Human Studies Review
This risk assessment relies in part on data from studies in which adult human subjects were intentionally exposed to a pesticide or other chemical.  These data, which include studies from PHED 1.1, the AHETF, the ARTF, the draft aquatic SOP and the Residential SOPs ( Lawns and Turf, Gardens and Trees) are (1) subject to ethics review pursuant to 40 CFR 26, (2) have received that review, and (3) are compliant with applicable ethics requirements.  For certain studies, the ethics review may have included review by the Human Studies Review Board.  Descriptions of data sources, as well as guidance on their use, can be found at the Agency website. 

 2.0	Risk Assessment Conclusions and Recommendations

There are no short- or intermediate-term occupational dermal risk estimates of concern associated with the registered uses of diquat dibromide.  However, risk estimates of concern exist for multiple inhalation occupational exposure scenarios. Furthermore, there are no short-term residential post-application swimmer or incidental oral risk estimates of concern, however multiple residential handler dermal and inhalation residential risk estimates of concern exist. There are no data gaps in the exposure database.

2.1	Summary of Risk Estimates 

 The occupational handler exposure and risk estimates indicate that the dermal MOEs are not of concern to HED; however, there are inhalation MOEs that are of concern for several scenarios with the use of label-recommended PPE (i.e., no respirator) and with the highest level of PPE and/or mitigation (i.e., PF10 respirator) available.  
 Occupational post-application dermal exposure and risk estimates were assessed for the golf course use and based on the current exposure assessment, an REI of 12 hours is necessary to reach acceptable MOEs (i.e., MOEs >= 100).  Current product label REIs are 24 hours; based on the acute toxicity of diquat dibromide, a REI of 24 hours would be sufficient under the current worker protection standard (WPS).
 The residential handler exposure and risk estimates indicate that the dermal MOEs are not of concern to HED; however there are inhalation MOEs that are of concern.
 The residential post-application exposure and risk estimates indicate that there are no risk estimates of concern.

2.2	Label Recommendations Residential

A summary of the risk estimates has been provided, and shows that there are residential risk estimates of concern for registered uses of diquat dibromide.

2.3 	Label Recommendations Occupational

A summary of the risk estimates has been provided, and shows that there are occupational risk estimates of concern for registered uses of diquat dibromide based on the use pattern and label-required personal protective equipment. 

2.4	Data Deficiencies and Requirements

Dislodgeable Foliar Residue (DFR):  In accordance with 40CFR158, DFR data are required for all occupational (e.g., crop, nursery, greenhouse use sites) or residential (e.g., ornamental and vegetable gardens, pick your own farms, retail tree farms) uses that could result in post-application exposure to foliage. In the case of diquat dibromide, due to the nature of the application (ground-directed, pre-, post-harvest defoliant/desiccant), post-application exposure is not expected; therefore, DFR data are not required at this time.   

Turf Transferable Residue (TTR):  In accordance with 40CFR158, TTR data are required for all occupational (e.g., sod farms, golf courses, parks, and recreational areas) or residential turf uses that could result in post-application exposure to turf.  In the absence of chemical-specific TTR data, EPA uses default values.  The 2012 Standard Operating Procedures for Residential Pesticide Exposure Assessment includes an analysis of all TTR data, available at the time, which resulted in the selection of revised liquid and granular default values for the fraction of the application rate available for transfer after a turf application (FAR).  These values are based on an analysis of 59 TTR studies performed with the Modified California Roller Method (36 studies using liquids, 11 studies using wettable powders/water dispersible granules, and 12 studies using granules).  The liquid results (N=131) indicate a range of FAR values from 0.0005% to 6.1 % and the granular results (N=37) indicate a range of 0.00064% to 0.69%.  In both the liquid and granular data, a large range of transferability is observed and this variability can potentially be attributable to many factors such as active ingredient; formulation; field conditions in the studies; weather conditions (e.g., humidity); or many other difficult to quantify factors.  Although witnessed across multiple chemicals, this range in FAR values is not expected when considering TTR data for a single chemical.   

HED selected 1% and 0.2% as high-end default values for liquid and granular products, respectively.  Because TTR data are not available for [diquat dibromide], EPA is using the default value of [1%].  Although there may be a small degree of uncertainty in the use of the default TTR value for [diquat dibromide] (i.e., there is a small chance that the  FAR value may exceed the applicable default value), it is likely that the health-protective aspects of EPA's [residential and/or occupational] post-application turf assessment methodology will more than compensate for this potential uncertainty (i.e., the methodology is likely to overestimate exposure by a factor greater than the factor than the highest measured FAR values exceed the defaults ).  For example,  when assessing residential post-application turf exposure, EPA assumes the following:  exposures occur to  zero-day (i.e., day of application ) residues every day of the assessed exposure duration (i.e., EPA assumes that no dissipation or degradation occurs, it doesn't rain, the grass is not mowed, etc); individuals perform the same post-application activities performed in the turf transfer coefficient study day after day (e.g., tumbling, playing on turf with toys, etc.); and individuals engage in these post-application activities for  a high-end amount of time every day that is represented by data reflecting time children spend outdoors and not specifically engaged in activities on turf, when in actuality children do not spend all of their outdoor time on turf and high-end levels of activity will not occur every day.  Given the conservatisms discussed above and the potential compounding nature of these conservatisms, EPA is able to rely upon the calculated exposure estimates with confidence that exposure is not being underestimated.    

In the case of diquat dibromide; default assumptions were used in all calculations. However, a DFR "turf" study (MRID: 40917402) was submitted. In that study, turf clippings were gathered and DFR residues were measured. HED believes that although these DFR values are not based on the Modified California Roller Method, sampling methodology was verified and therefore satisfies the study data requirements.

Since the estimated residential turf post-application exposure for residential turf/mower/golf course using default TTR values for diquat dibromide is not minimal in comparison to the level of concern (i.e., the calculated MOE is not greater than 10 times higher than the level of concern, MOE = 150 compared to the LOC of 100), future refinements of this post-application exposure for diquat dibromide may be necessary due to increased use of diquat dibromide or advances in EPA risk assessments. 

3.0	Hazard Characterization

The eye was a target organ following subchronic and chronic oral exposures in rats, mice, and dogs causing opacity, lesions, discharge, and cataracts at doses greater than those eliciting clinical signs.  The physical properties of diquat indicate it is highly hydrophilic and such chemicals will often cause ocular effects due to the high water content of the eye.  Clinical signs and body weight decrements were noted throughout the database following acute, subchronic, and chronic exposures to diquat.  The majority of the clinical signs were associated with ocular toxicity (e.g., eye discharge, opaque eyes) or general systemic toxicity (e.g., diarrhea, urinary incontinence, lack of grooming).  In several studies, including the acute neurotoxicity study, there was evidence of potential neurotoxicity based on increased incidence of piloerection, abnormal posture and gait, and subdued behavior; however, these signs are most likely indicative of overt toxicity rather than direct neurotoxicity since they were only seen at the highest dose tested and are consistent with those observed at overtly toxic doses in other studies following diquat exposure.

There was no evidence of increased pre- or post-natal susceptibility.  The maternal/parental effects were consistent with those seen in the toxicological database, and observed at doses at or below those producing developmental (decreased fetal body weights and skeletal variations) or offspring (reduced number of live pups, kidney lesions, and body weight decrements) effects.
An acceptable route-specific inhalation subchronic toxicity study in rats is available for diquat.  Portal of entry effects occurred at doses much lower than those eliciting oral toxicity and consisted of microscopic lung lesions and increased lung weights in both sexes.  



Acute Toxicity
Diquat dibromide is classified as Acute Toxicity Categories II or III via the oral, dermal, and inhalation routes. Diquat dibromide is not an acute skin irritant (Toxicity Category IV) nor a dermal sensitizer, but it is considered a moderate-to-severe eye irritant (Toxicity Category II). Acute toxicity categories for diquat dibromide are shown in Table 3.1.

Table 3.1. Acute Toxicity of Diquat Dibromide.
                                 Guideline No.
                                  Study Type
                                   MRID No.
                                    Results
                               Toxicity Category
                                   870.1100
                                  Acute Oral
                                   00081506
                             rat LD50 = 810 mg/kg 
                             rat LD50 = 600 mg/kg 
                                      III
                                   870.1200
                                 Acute Dermal
                                   00010014
                           rabbits LD50 = 262 mg/kg
                           rabbits LD50 = 315 mg/kg
                          rabbits LD50 = 288.5 mg/kg
                                      II
                                   870.1200
                                 Acute Dermal
                                   49797702
                           Rat LD50 > 2000 mg/kg
                       (diquat ion LD50 > 424 mg/kg)
                                   II or III
                                   870.1200
                                 Acute Dermal
                                (non-guideline)
                                   00061634
                                 LD50 between 
                         200 and 400 mg diquat ion/kg
                                      II
                                   870.1300
                               Acute Inhalation
                                   00026385
                             rat LC50 = 0.80 mg/L
                             rat LC50 = 1.09 mg/L
                             rat LC50 = 0.97 mg/L
                                      III
                                   870.2400
                           Primary Eye  Irritation
                                   00081507
                       Rabbit slight to severe irritant
                                      II
                                   870.2500
                            Primary Skin Irritation
                                   00107903
                               slight-irritating
                                      IV
                                   870.2600
                             Dermal Sensitization
                                   00107903
                               not a sensitizer
                                      N/A
With the exception of the dermal sensitization study, which was conducted with the technical diquat (Diquat Herbicide Concentrate), the above studies were conducted with the end-use products [Diquat Water Weed Killer and Diquat 2 Spray (eye irritation study only)] and not in terms of the diquat ion.  Because the only difference between the technical diquat and the end-use products is 2.15% water, studies with the end-use products have been accepted to satisfy the generic data requirements for acute studies.  The above LD and LC values are mostly expressed in terms of the test material and not, as is commonly done with diquat, in terms of the diquat cation.

Toxicological PODs Used for Risk Assessment
The following points of departure (PODs) have been chosen for diquat dibromide: 1) a no observed adverse effect level (NOAEL) of 3 mg/kg/day from a developmental toxicity study in rabbits for short-or intermediate-term dermal and incidental oral exposures; 2) a NOAEL of 0.01 ug/L from a subchronic inhalation toxicity study in rats.  See Tables 3.2 and 3.3 for details regarding selected residential and occupational PODs, respectively.

HECs for residential and occupational inhalation scenarios were derived using the NOAEL and the regional deposited dose ratio (RDDR).  The RDDR accounts for the particulate diameter [mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD)] and estimates the different dose fractions deposited along the respiratory tract.  The RDDR also accounts for interspecies differences in ventilation and respiratory tract surface areas.  For the subchronic inhalation toxicity study with diquat, a RDDR was estimated at 0.591 based the pulmonary effects seen at the LOAEL of 0.49 ug/L, with a MMAD of 1.9 um and GSD of 1.9.  

HECs of 4.4x10[-5] mg/L for occupational worker exposure and 5.9x10[-5] mg/L for residential handler and outdoor post-application exposures were obtained.  Subsequent human equivalent dose values of 0.0042 mg/kg/day and 0.0014 mg/kg/day were calculated for these occupational and residential exposure assessments, respectively.  HEC and human equivalent dose calculations are summarized in Table 3.4.  The standard interspecies extrapolation uncertainty factor can be reduced from 10X to 3X due to the calculation of HECs accounting for pharmacokinetic (not pharmacodynamic) interspecies differences.  Therefore, the LOC for inhalation exposures is 30 (3X for interspecies extrapolation, 10X for intra-species variation, and 1X for FQPA SF when applicable).  

Table 3.2 Summary of Toxicological Doses and Endpoints for Diquat Dibromide for Use in Dietary and Non-Occupational Human Health Risk Assessments
                              Exposure/ Scenario
                           Point of Departure (POD)
                        Uncertainty/FQPA Safety Factors
                RfD, PAD, Level of Concern for Risk Assessment
                        Study and Toxicological Effects
Incidental Oral 
Short-Term
(1-30 days) and Intermediate-Term (1-6 months)
                              NOAEL = 3 mg/kg/day
                                   UFA = 10X
                                   UFH = 10X
                                   FQPA = 1X
Residential LOC = 100
Developmental Toxicity Study in Rabbits
LOAEL = 10 mg /kg/day based on clinical signs
Dermal
Short-Term
(1-30 days) and Intermediate-Term (1-6 months)
                              NOAEL = 3 mg/kg/day
                                       
                           Dermal absorption factor 
                                 (DAF) = 0.3%
                                   UFA = 10X
                                   UFH = 10X
                                   FQPA = 1X
Residential LOC = 100
Developmental Toxicity Study in Rabbits
LOAEL = 10 mg /kg/day based on  clinical signs
Inhalation
Short-Term
(1-30 days) and Intermediate-Term (1-6 months)
                               NOAEL = 0.1 ug/L
                                 (0.0001 mg/L)
                                   UFA = 3X
                                   UFH = 10X
                                   FQPA = 1X
Residential LOC = 30
Subchronic Inhalation Toxicity Study in Rats
LOAEL = 0.49 ug/L (0.00049 mg/L) based on increased mean lung weights and microscopic lesions in the lung
Cancer (oral, dermal, inhalation)
Classified as "Category E - evidence of non-carcinogenicity for humans"
Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and  used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures.  NOAEL = no observed adverse effect level.  LOAEL = lowest observed adverse effect level.  UF = uncertainty factor.  UFA = extrapolation from animal to human (interspecies).  UFH = potential variation in sensitivity among members of the human population (intra-species).  FQPA SF = FQPA Safety Factor.  PAD = population adjusted dose (a = acute, c = chronic).  RfD = reference dose (a= acute, c = chronic).  MOE = margin of exposure.  LOC = level of concern.  

Table 3.3 Summary of Toxicological Doses and Endpoints for Diquat Dibromide for Use Occupational Human Health Risk Assessments
                              Exposure/ Scenario
                              Point of Departure
                          Uncertainty Safety Factors
                RfD, PAD, Level of Concern for Risk Assessment
                        Study and Toxicological Effects
Dermal
Short-Term
(1-30 days) and Intermediate-Term (1-6 months)
                              NOAEL = 3 mg/kg/day
                                       
                           Dermal absorption factor 
                                 (DAF) = 0.3%
                                   UFA = 10X
                                   UFH = 10X
Occupational LOC = 100
Developmental Toxicity Study in Rabbits
LOAEL = 10 mg /kg/day based on clinical signs.
Inhalation
Short-Term
(1-30 days) and Intermediate-Term (1-6 months)
                                       
                        NOAEL = 0.1 ug/L (0.0001 mg/L)
                                       
                                       
                                   UFA = 3X
                                   UFH = 10X
Occupational LOC = 30
Subchronic Inhalation Toxicity Study in Rats
LOAEL = 0.49 ug/L (0.00049 mg/L) based on increased mean lung weights and microscopic lesions in the lung
Cancer (oral, dermal, inhalation)
Classified as "Category E - evidence of non-carcinogenicity for humans"
Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and  used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures.  NOAEL = no observed adverse effect level.  LOAEL = lowest observed adverse effect level.  UF = uncertainty factor.  UFA = extrapolation from animal to human (interspecies).  UFH = potential variation in sensitivity among members of the human population (intra-species).  FQPA SF = FQPA Safety Factor.  PAD = population adjusted dose (a = acute, c = chronic). RfD = reference dose (a = acute, c = chronic).  MOE = margin of exposure.  LOC = level of concern.  

Table 3.4 Summary of Inhalation Calculations for Human Equivalent Concentrations and Doses for Diquat Dibromide.
                                  Population
                                   Scenario
                        Toxicity Duration Adjustment[a]
                       Human Equivalent Concentration[b]
                             Human Equivalent Dose
                                       
                                       
                                   hours/day
                                   days/week
                                     mg/L
                                    mg/m[3]
                                   mg/kg/day
                                 Occupational
                                    Handler
                                       8
                                       5
                                  4.43x10[-5]
                                     0.044
                                    0.0042
                                  Residential
                                    Handler
                                      NA
                                      NA
                                  5.91x10[-5]
                                     0.059
                                    0.0014

                           Outdoor post-application
                                      NA
                                      NA
                                  5.91x10[-5]
                                     0.059
                                      NA

                            Indoor post-application
                                      NA
                                       7
                                  4.22x10[-5]
                                     0.042
                                      NA

                                   Bystander
                                      24
                                       7
                                  1.06x10[-5]
                                     0.011
                                      NA
a. Toxicity duration adjustment from 6 hours/day, 5 days/week exposure in rat study.
b. Human equivalent concentrations calculated using duration adjustments, when applicable, and a pulmonary regional deposited dose ratio (RDDR) of 0.591, which was obtained with a mass median aerodynamic diameter (MMAD) of 1.9, a geometric standard deviation (GSD) of 1.9, and the default combined sex body weight for Fischer 344 rats of 152 g.
NA = not applicable (the expected duration of the exposure scenario is less than the duration of available inhalation toxicity studies; downward adjustments are not permitted).

Absorption:
A dermal absorption factor of 0.3% was estimated from a human dermal absorption study (MRID 43736616). 

Body Weight:
The standard body weight for the general population (80 kg) was used for all exposure scenarios covered in this risk assessment since the endpoints selected were not developmental and/or fetal effects. Body weights of 57, 32, and 11 kilograms were used for the different child life-stages associated with residential post-application, incidental oral, and spray drift exposure scenarios.




4.0	Use Profile 

Table 4.1 provides a summary of the registered uses of diquat dibromide.

Table 4.1.  Summary of Directions for Use of Diquat Dibromide.
                       Applic. Timing, Type, and Equip.
                                     Crop
                            Formln. [EPA Reg. No.]
                                Applic. Rate[1]
                                       
                           Max. No. Appl. Per Season
                          Max. Seasonal Appl. Rate[2]
                                       
                             Pre-harvest Interval
                                     (PHI)
                                    (Days)
                        Use Directions and Limitations
                  Use Site 1 (Terrestrial Crop and Farmland)
                                       
                                 Pre-harvest/
                                 desiccation 
                                  Ground and
                                    Aerial
                               Alfalfa, Clover,
                                  (Seed crop)
                                      SC
                             (EPA Reg.# 100-1061)
                                       
                                     0.5 
                                  lb ai/Acre
                                       
                                       2
                                1.0  lb ai/Acre
                                       3
                   Do not apply through irrigation systems.
               Do not graze or feed treated forage to livestock
      Do not use seed from treated plants for food, feed or oil purposes
                                       
                                     24C:
                                  FL- 000009
                                   SC-000005
                                       
                                Potato, Canola
                                       
                                       
                                       
                                       
                                       7
                                       
                              Non-bearing crops:
                             Ground Directed Spray
                                Crop Groups [3]
                   4, 13-07, 14-12, 10-10, 99, 12-12, 11-10
                                      SC
                             (EPA Reg.# 100-1061)
                                       
                                       
                                       5
                                2.5 lb ai/Acre
                                      365
                                       
                            Post-Harvest burn down:
                                       
                                       
                                  Groundboom.
                                 Tomato Vines
                                       
                                0.38 lb ai/Acre
                                       2
                                0.75 lb ai/Acre
                                      N/A
                                       
                                       
                               Cantaloupe Vines
                                      SC
                             (EPA Reg.# 100-1061)
                                       
                                0.25 lb ai/Acre
                                       
                                0.5 lb ai/Acre
                                       
                                       
                                       
                         Cucumber, Squash, Watermelon
                                       
                                0.38 lb ai/Acre
                                       
                                0.75 lb ai/Acre
                                       
                                       
                                       
                             Acorn squash, Peppers
                                       
                                0.5 lb ai/Acre
                                       
                                 1 lb ai/Acre
                                       
                                       
                                 Weed control:
                                  Middle Rows
                             Ground Directed Spray
                        Eggplant, Green Pepper, Tomato
                                      SC
                             (EPA Reg.# 100-1061)
                                       
                                  0.5 lb ai/A
                                       
                                       2
                                 1 lb ai/Acre
                                      30
                     Do not apply when wind speed exceeds
                                     5 mph
                                       
                                     24C:
                                   FL-000010
                                   PR-030001
                            Pre-Harvest desiccation
                                       
                               Ground and Aerial
Carrots, Coriander, Radishes, Spinach, Sugar Beets, Table Beet, Turnips, Calendulas
                                      SC
                             (EPA Reg.# 100-1061)
                                       
                                  0.5 lb ai/A
                                       
                                       1
                                0.5 lb ai/Acre
                                       3
Do not apply through irrigation systems. Use only on non-edible oilseed varieties of calendula. 
                                       
                                     24C:
                                   WA-040011
                                   OR-080025
                                   ID-100006
                                   MN-090006
                    Non-Crop or Non-Planted Areas on Farms
                                       
                                Ground Directed
Fence Lines, Farmyards, Farm Buildings, Fuel Storage Areas, barrier Strips, and Equipment Areas around ponds, lakes and drainage ditches on farms.
                                      SC
                             (EPA Reg.# 100-1061)
                                       
                                0.5 lb ai/Acre
                                      10
                                 5 lb ai/Acre
                                      N/A
For spot treatments, apply 2 qt product/100 gallon water (or 22 ml product/1 gallon water)
                       Use Site 2 (Non-Crop Terrestrial)
                            Pre-harvest Desiccation
                                Ground directed
                             Ornamental seed crops
                                      SC
                                  (EPA Reg.#
                              100-1091, 100-1390)
                                0.5 lb ai/Acre
                                       3
                                1.5 lb ai/Acre
                                      N/A
Do not apply through any type of irrigation system. For seed crop only. Not for food or fiber crops. Not allowed in California.
                                       
Commercial Greenhouse (beneath benches), field grown and container stock and other similar areas 
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                 Landscape, Industrial, Commercial  areas [4]
                            including golf courses
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                Turf Renovation
                                       
                                       
                                       2
                                 1 lb ai/Acre
                                       
                                       
                                       
                        Dormant Established Turf Grass
                                       
                                       
                                       
                                       
                                       
                                       
           Pre-plant, Pre-emergence,   Post-Emergence Directed Spray
                          (Spot/Broadcast Treatments)
Commercial Greenhouse (beneath benches), field grown and container stock and other similar areas 
                                       
                            0.01 to 0.04 lb ai/gal
                                       5
                                 2 lb ai/Acre
                                       
Not for food or fiber crops. Avoid spray contact with foliage of food crops or ornamental plants or other desirable vegetation
                                       
       Landscape, Industrial, Commercial, Residential and Public Areas 
                                       

                                       
                                       
                                       
                                       
              Use Site 3 (Aquatic - Occupational and Residential)
Aquatic Broadcast  around lakes, ponds, drainage ditches, reservoirs, marshes, canals and rivers
                                       
                      Floating and Marginal Surface Weeds
                                      SC
                                  (EPA Reg.#
                              100-1091, 100-1390)
                              4 lb ai/ Acre/1ft 
                                      10
                                       
                                       
       See table in Appendix B for extensive directions and limitations.
                                    24C [5]
                                   FL-030006
                                   FL-110009
                                   ID-070012
                                   AL-07001
                                   GA-080004
                                   NY-030001
                                   NY-120007
                                       
                                Submersed Weeds
                                       
                             4 lb ai/ Acre/4 feet 
                                       
                                       
                                       
                                       
                                       
                                       
                 Standing and Flowing Water - Submerged Weeds
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                         Still Water - Submerged Weeds
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                         Still Water - Floating Weeds
                                       
                              1.5 lb ai/ Acre/3ft
                                       
                                       
                                       
                                       
                                       
                       Still Water - Duckweed, Cattails
                                       
                               2 lb ai/ Acre/3ft
                                       
                                       
                                       
                                       
                                   Injection
                or High Pressure Spray into Sewer Systems Pipes
                          Tree Root Mass in Pipelines
                                      SC
                                  (EPA Reg.#
                                    64898-8
                                0.01 lb ai/gal
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                 Aquatic [6] 
                                Spot Treatment
                          Floating and Marginal Weeds
                                      SC
                                  (EPA Reg.#
                              100-1091, 100-1390)
                                0.04 lb ai/gal
                                       
                                40 lb/Sq. Acre
                                      N/A
                                See Appendix A
                                 Aquatic Uses
                                       
                                       
                                       
                             0.000092 lb ai ft[2]
                                       
                                      N/A
                                       
                                       
                          Use Site 3 (Residential)[7]
                         Manually Pressurized Handwand
                              Gardens/Trees/Turf
                                      SC
                                  (EPA Reg.#
                              100-1091, 100-1390)
                                0.01 lb ai/gal
                                      N/A
                                      N/A
                                      N/A
                                      N/A
                                       
                                       
                                       
                                0.5 lb ai/Acre
                                       
                                       
                                       
                                       
                               Backpack Sprayer
                                       
                                       
                                0.01 lb  ai/gal
                                       
                                       
                                       
                                       
                             Trigger-spray Bottle
                                       
                                       
                            0.0025 lb ai/bottle[8]
                                       
                                       
                                       
                                       
1, 2 Rate = Maximum application rates specified on labels (EPA Reg. # 100-1061 "Master Label", 1091, 1390, and "sewer uses" 64898-8); Use pattern matrix supplied by email:  PRD 9/5/2014, 7/30/2014, and SRRD use index 8/28/2014; TRED (D281890). For information concerning the 1,125 gallons used for sewer applications See Memorandum, DP # 357118 titled, Metam Sodium: Third Revision of the HED Human Risk Assessment, Dated April 30, 2009.
3. Crop groups (4, 13-07, 14-12, 10-10, 99, 12-12, 11-10): vegetable, leafy, except brassica; fruit, berry and small fruit; nut, tree; fruit, citrus; fruit, stone; fruit, pome.
4. Areas of use; around trees ornamental gardens, beneath commercial greenhouse Benches. Other Non-Crop Areas: buildings, parking lots, cart paths, patios, dividers, pipelines, driveways, public utility lines, electric utilities, pumping stations, fence lines, railroad beds/yards, golf courses, rights of way, highways, roads, landscape beds, roadsides, lawns, transformer stations and substations, medians, walkways, non-flooded portions of ponds, lakes and ditches.	
5. Labels direct 24C registrations to not treat water where depth is 3 feet or less and to not apply by air.		
6. Label rate: 4 lb ai/Acre x Acre/43,560 sq ft = 0.000092 lb ai/ft sq.
7. Residential use information: See TRED (D281890) for specifics
8. TRED - (D281890): Trigger Sprayer:  high end = 0.01 lb ai.gal, so: 0.01 lbs ai/gal x gal/128 fl. oz. x 32 fl. oz/bottle = 0.0025 lb ai/bottle (32 fl. oz).
9. REI = 24 hr. (for occupational uses)


5.0	Residential Exposure and Risk Estimates

Residential uses have been reassessed in this documents to reflect updates to HED's 2012 Residential SOPs and the November 2015 Aquatic use SOP along with policy changes for body weight assumptions. The revision of residential exposures will impact the human health aggregate risk assessment for diquat dibromide.

5.1	Residential Handler Exposure/Risk Estimates

HED uses the term "handlers" to describe those individuals who are involved in the pesticide application process.  HED believes that there are distinct tasks related to applications and that exposures can vary depending on the specifics of each task.  Residential handlers are addressed somewhat differently by HED as homeowners are assumed to complete all elements of an application without use of any protective equipment.
 
The quantitative exposure/risk assessment developed for residential handlers is based on the following scenarios: 

Mixing/Loading/Applying:

 Manually Pressurized Handwand: Gardens/Trees/Turf (around the home and garden), residential lawns, ornamentals, and greenhouses. Aquatic herbicide/algaecide uses include Recreational/back yard ponds. 
 Backpack Sprayer: Gardens/Trees/Turf (around the home and garden). Aquatic herbicide/algaecide uses include Recreational/back yard ponds. 
      
Applying:

 Trigger-Spray Bottle: Ready-to-use (R-T-U); Gardens/Trees/Turf (around the home and garden).

Residential Handler Exposure Data and Assumptions
A series of assumptions and exposure factors served as the basis for completing the residential handler risk assessments.  Each assumption and factor is detailed below.

Application Rate: 
See table 4.1 for specifics.

Unit Exposures and Area Treated or Amount Handled:
Unit exposure values and estimates for area treated or amount handled were taken from HED's 2012 Residential SOPsand the November 2015 Aquatic use SOP. 

Exposure Duration:  
Residential handler exposure is expected to be short-term in duration.  Intermediate-term exposures are not likely because of the intermittent nature of applications by homeowners.
Residential Handler Non-Cancer Exposure and Risk Estimate Equations
The algorithms used to estimate exposure and dose for residential handlers can be found in Appendix A and/or the 2012 Residential SOPs and the November 2015 Aquatic use SOP.



Summary of Residential Handler Non-Cancer Exposure and Risk Estimates
For most short-term residential handler and post-application exposure scenarios, there are no risk estimates of concern associated with the use of diquat dibromide (i.e., MOEs >= 100 for dermal or incidental oral, and MOEs >= 30 for inhalation). However, the following inhalation exposure scenarios presented risks of concern:
 Backpack sprayer applications to gardens, trees and turf (lawns) 
 Backpack sprayer applications for aquatic uses for recreational/backyard ponds.

Table 5.1.1.  Residential Handler Non-cancer Exposure and Risk Estimates for diquat dibromide.
                               Exposure Scenario
                        Dermal Unit Exposure (mg/lb ai)
                      Inhalation Unit Exposure (mg/lb ai)
                                     Max. 
                                     App.
                                    Rate[1]
                    Area Treated or Amount Handled Daily[2]
                                    Dermal
                                  Inhalation
                                       
                                       
                                       
                                       
                                       
                              Dose (mg/kg/day)[3]
                                    MOE[4]
                                  (LOC = 100)
                              Dose (mg/kg/day)[5]
                                    MOE[6]
                                   (LOC =30)
                 Mixer/Loader/Applicator (Soluble Concentrate)
                        Manually-pressurized Handwand/
                        Handgun  to Turf/Gardens /Trees
                                      63
                                     0.018
                                     0.01
                                   lb ai/gal
                                     5 gal

                                    0.00012
                                    25,000
                                    0.000011
                                      120
                           Backpack Sprayer to Turf
                                       
                                      130
                                       
                                     0.14
                                     0.01
                                   lb ai/gal
                                       
                                    0.00024
                                    12,000
                                   0.000088
                                      16
                     Backpack Sprayer to Gardens and Trees
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                             Trigger-Spray bottle
                             to Gardens and Trees
                                     85.1
                                     0.061
                                    0.0025
                                    lb ai/
                                   bottle[7]
                                   2 bottles
                                   0.000016
                                    190,000
                                   0.0000038
                                      370
                             Trigger-Spray bottle
                                 to Lawns/Turf
                                       
                                       
                                       
                                   1 bottle
                                   0.000008
                                    380,000
                                   0.0000019
                                      730
                                 Aquatic Areas
                         Manually-pressurized Handwand
                                      63
                                     0.018
                             0.000092 lb ai/ft[2]
                                   500 ft[2]
                                    0.00011
                                       
                                    28,000
                                       
                                       
                                    0.00001
                                       
                                       
                                      140
                                       
                               Backpack Sprayer
                                      130
                                     0.14
                             0.000092 lb ai/ft[2]
                                   500 ft[2]
                                    0.00022
                                    13,000
                                   0.000081
                                      17
1. Application rates primarily based on use information provided by Registrant (supplied by email from PRD 9/5/2014, 7/30/2014).  The use information provided was noted to be based primarily on representative Section 3 and 24C labels from Syngenta Crop Protection.  In addition, information provided in the TRED (D281890) for diquat was used for the residential use information. 
2.  Based on HED's Standard Operating Procedures for Residential Pesticide Exposure Assessment; Lawns/Turf (Feb. 2012) and   November 2015 Aquatic SOP.
3.  Dose (mg/kg/day) = daily unit exposure (mg/ - lb ai) x application rate (lb ai/area treated or amount handled) x Area treated or    amount handled * absorption factor (inhalation = 100 % and dermal = 0.3%) / -  body weight (80 kg).
4.  Dermal MOE = NOAEL (3 mg/kg/day) / daily dose (mg/ - kg/ - day).  Level of concern = 100.
5.  Inhalation Dose = daily unit exposure (mg/ - lb ai) x application rate (lb ai/area treated or amount handled) x Area treated or   amount handled / -  body weight (80 kg).
6.  Inhalation MOE = Human equivalent dose (0.0014 mg/kg/day) / daily dose (mg/ - kg/ - day).  Level of concern = 30.



5.2	Residential Post-application Exposure/Risk Estimates

There is the potential for post-application exposure for individuals exposed as a result of being in an environment that has been previously treated with diquat dibromide.  The quantitative exposure/risk assessment for residential post-application exposures is based on the following scenarios: 

 Lawns and Turf:
 High contact activities, mowing and golfing (used on resistant dormant turf (Bermuda and Zoysia grass) for weed control. 
 Incidental Oral: Hand to mouth (HtM), Object to Mouth (OtM), and Soil Ingestion (SI)

Gardens and Trees:
 Garden activities 
   
Aquatic Activities:
 Swimming

The lifestages selected for each post-application scenario are based on an analysis provided as an Appendix in the 2012 Residential SOPs.  

Application Rate: 
See table 4.1 for details.

Exposure Duration: 
Residential post-application exposure is expected to be short-term in duration.  Intermediate-term exposures are not likely because of the intermittent nature of applications by homeowners.
 
Residential Post-application Non-Cancer Exposure and Risk Equations
The algorithms used to estimate residential post-application exposure and dose can be found in Appendix A and/or the 2012 Residential SOPs. 

Summary of Residential Post-application Non-Cancer Exposure and Risk Estimates
For calculation of residential post-application exposure, a developmental study was used for the dermal and incidental oral route based on clinical signs, while a route-specific inhalation study was used for the inhalation route based on lesions in the lung and lung weights. Therefore, dermal and incidental oral exposures are combined, whereas they are based on the same effects and have the same NOAEL of 3 mg/kg/day, however, inhalation exposure will not be combined. The incidental oral scenarios (i.e., hand-to-mouth and object-to-mouth) should be considered inter-related and it is likely that they occur interspersed amongst each other across time.  Combining these scenarios with the dermal exposure scenario would be overly-conservative because of the conservative nature of each individual assessment.  Therefore, the post-application exposure scenarios that were combined for children 1 < 2 years old are the dermal and hand-to-mouth scenarios.  The residential post-application exposures are summarized in tables 5.2.1 and 5.2.2.  All dermal and incidental oral MOEs are >= 100.

Table 5.2.1.  Residential Post-application Non-cancer Exposure and Risk Estimates for Diquat Dibromide.
                                   Lifestage
                      Post-application Exposure Scenario
                              Application Rate[1]
                              Dose (mg/kg/day)[2]
                                    MOEs[3]
                                Combined Routes
                         (X: included in Combined MOE)
                               Combined MOEs[4]
                                       
                                   Use Site
                          Route of Exposure/Activity
                                       
                                       
                                       
                                       
                                       
                                     Adult
                                       
                                  Lawns and 
                                     Turf
                                       
                                       
                                       
                                       
                                       
                                       
                                  Lawns and 
                                     Turf
                                       
                       Dermal / High Contact Activities 
                                       
                                       
                                       
                                     0.5 
                                  lb ai/Acre
                                       
                                       
                                       

                                     0.5 
                                  lb ai/Acre
                                    0.00060
                                     5,300
                                      N/A
                                      N/A
                                       
                                       
                                Dermal / Mowing
                                       
                                   0.000012
                                    260,000
                                      N/A
                                       
                                       
                                       
                               Dermal / Golfing
                                       
                                   0.000044
                                    68,000
                                      N/A
                                       
                                     Child
                             1 to < 2 years old
                                       
                                     Child
                             1 to < 2 years old
                                       
                                       
                       Dermal / High Contact Activities 
                                       
                                    0.0011
                                     2,700
                                       X
                                      350
                                       
                                       
                        Incidental oral / hand to mouth
                                       
                                    0.0076
                                      390
                                       X
                                       
                                       
                                       
                       Incidental oral / Object to mouth
                                       
                                    0.00023
                                    13,000
                                      N/A
                                      N/A
                                       
                                       
                                       
                       Incidental oral / soil ingestion
                                       
                                    1.7E-05
                                    180,000
                                      N/A
                                       
                                     Child
                            11 to < 16 years old
                                Lawns and Turf
                                Dermal / Mowing
                                      0.5
                                   lb ai/Acre
                                   0.000013
                                    230,000
                                      N/A
                                      N/A
                                     Child
                                 11 to < 16
                                   Years old
                                       
                               Dermal / Golfing
                                       
                                    0.00052
                                    58,000 
                                      N/A
                                       
                                     Child
                                 6 to < 11 
                                  Years old 
                                       
                                       
                                       
                                   0.000060
                                    50,000
                                      N/A
                                      N/A
                                     Adult
                                    Gardens
                              General Activities
                                       
                                    0.00096
                                     3,100
                                      N/A
                                       
                                     Child
                                6 < 11 years
                                    Gardens
                              General Activities
                                       
                                    0.00070
                                     4,600
                                       
                                       
                                     Adult
                                    Aquatic
                                  (swimming)
                                  Inhalation
                                   0.000092 
                                 lb ai/ft [2]
                                   7.75E-12
                                   1.80E+08
                                      N/A
                                   1.80E+08
                                       
                                       
                                    Dermal
                                       
                                   7.17E-09
                                   4.20E+08
                                       X
                                   4.20E+08
                                       
                                       
                                   Ingestion
                                       
                                   2.88E-06
                                   1.00E+06
                                       X
                                       
                                     Child
                             3 to < 6 years old
                                       
                                  Inhalation
                                       
                                   5.35E-11
                                   2.62E+07
                                      N/A
                                   2.62 E+07
                                       
                                       
                                    Dermal
                                       
                                   2.94E-08
                                   1.00E+08
                                       X
                                   1.02E+08
                                       
                                       
                                   Ingestion
                                       
                                   3.03E-05
                                   9.90E+04
                                       X
                                       
1	Application rates primarily based on use information provided by Registrant (supplied by email from PRD 9/5/2014, 7/30/2014).  The use information provided was noted to be based primarily on representative Section 3 and 24C labels from Syngenta Crop Protection.  In addition, information provided in the TRED (D281890) for diquat was used for the residential use information. 
2	Dose (mg/kg/day) equations provided in Appendix [A]. Lawns/Turf, Gardens/Trees, Aquatic (swimming).
3	MOE = POD (mg/kg/day) / Dose (mg/kg/day).
4	Combined MOE = POD (3 mg/kg/day) / (dermal dose + incidental oral dose).

5.3 	Residential Risk Estimates for Use in Aggregate Assessment

There were certain scenarios that did not reach the LOC of 100 for dermal and 30 for inhalation, therefore only the residential exposure scenarios that were not of concern (MOE >= 100 for dermal and 30 for inhalation) have been recommended for the aggregate assessment.
Table 5.3.1 reflect the residential risk estimates that are recommended for use in the aggregate assessment for diquat dibromide.

 The recommended residential exposure for use in the adult aggregate assessment reflects dermal exposures from high contact activities on outdoor treated turf.
      
 The recommended residential exposure for use in the children 1 to 2 years old aggregate assessment reflects exposures from high contact activities on outdoor treated turf.


Table 5.3.1 Recommendations for the Residential Exposures for the Diquat Dibromide Aggregate Assessment.
                                   Lifestage
                               Exposure Scenario
                              Dose (mg/kg/day)[1]
                                    MOE [2]
                                       
                                       
                                    Dermal
                                  Inhalation
                                     Oral
                                     Total
                                    Dermal
                                  (LOC = 100)
                                 Inhalation[3]
                                  (LOC = 30)
                                     Oral
                                     Total
                                     Adult
              Postapp: High contact activities from treated turf
                                    0.0006
                                      N/A
                                      N/A
                                      N/A
                                     5,300
                                      N/A
                                      N/A
                                      N/A
                                    Child 
                                   (1 to 2 
                                  years old)
                   High contact activities from treated turf
                                    0.0011
                                      N/A
                                    0.0076
                                     0.0087
                                     2,700
                                      N/A
                                      390
                                      350
1.	Dose = the highest dose for each applicable life stage of all residential scenarios assessed.  Total = dermal + incidental oral (where applicable).
2. Total MOE = [3.0 mg/kg/day / (combined dermal) + (oral dose)], where applicable.
3. Inhalation endpoint is based on a different study with different effects thus not combined.

5.4	Spray Drift

Off-target movement of pesticides can occur via many types of pathways and it is governed by a variety of factors.  Sprays that are released and do not deposit in the application area end up off-target and can lead to exposures to those it may directly contact. They can also deposit on surfaces where contact with residues can eventually lead to indirect exposures (e.g., children playing on lawns where residues have deposited next to treated fields). The potential risk estimates from these residues can be calculated using drift modeling onto 50 feet wide lawns coupled with methods employed for residential risk assessments for turf products.

The approach to be used for quantitatively incorporating spray drift into risk assessment is based on a premise of compliant applications which, by definition, should not result in direct exposures to individuals because of existing label language and other regulatory requirements intended to prevent them.  Direct exposures would include inhalation of the spray plume or being sprayed directly.  Rather, the exposures addressed here are thought to occur indirectly through contact with impacted areas, such as residential lawns, when compliant applications are conducted.  Given this premise, exposures for children (1 to 2 years old) and adults who have contact with turf where residues are assumed to have deposited via spray drift thus resulting in an indirect exposure are the focus of this analysis analogous to how exposures to turf products are considered in risk assessment.  

Several diquat dibromide products have existing labels for use on turf, thus it was considered whether the risk assessment for that use may be considered protective of any type of exposure that would be associated with spray drift.  It should be noted that the registered residential uses on turf result in exposure greater than potential exposure from spray drift; therefore, no new residential assessment needs to be completed.  If the maximum application rate on crops adjusted by the amount of drift expected is less than or equal to existing turf application rates, the existing turf assessment is considered protective of spray drift exposure.  The currently registered maximum single application rate of diquat dibromide for crops is 0.5 lb ai/A.  The highest degree of spray drift noted for any application method immediately adjacent to a treated field (Tier 1 output from the aerial application using fine to medium spray quality) results in an deposition fraction of 0.26 of the application rate.  A quantitative spray drift assessment for diquat dibromide is not required because the maximum application rate to a crop/target site multiplied by the adjustment factor for drift of 0.26 is less than the maximum direct spray residential turf application rate (0.5 lb ai/A) for any diquat dibromide products.  The turf post-application MOEs have been previously assessed and are based on the revised SOPs for Residential Exposure Assessment (i.e., see above in Section 5.2).  

For aquatic uses, subsurface, bottom placement, and surface applications may be made.  The only application with the potential for spray drift is surface application as a spray. Although the label does not prohibit the use of aerial applications for aquatic areas, it is unlikely aerial applications would be made given the types of water bodies the product is being applied to and the alternative application options (handheld application equipment).  

5.5	Residential Bystander Post-Application Inhalation Exposure

Volatilization of pesticides may be a source of post-application inhalation exposure to individuals nearby pesticide applications.  The agency sought expert advice and input on issues related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, and received the SAP's final report on March 2, 2010 (http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html).  The agency has evaluated the SAP report and has developed a Volatilization Screening Tool and a subsequent Volatilization Screening Analysis (http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219). During Registration Review, the agency will utilize this analysis to determine if data (i.e., flux studies, route-specific inhalation toxicological studies) or further analysis is required for diquat dibromide.

6.0	Occupational Exposure and Risk Estimates
6.1	Occupational Handler Exposure/Risk Estimates

HED uses the term handlers to describe those individuals who are involved in the pesticide application process.  HED believes that there are distinct job functions or tasks related to applications and exposures can vary depending on the specifics of each task.  Job requirements (amount of chemical used in each application), the kinds of equipment used, the target being treated, and the level of protection used by a handler can cause exposure levels to differ in a manner specific to each application event.  

Based on the anticipated use patterns and current labeling, types of equipment and techniques that can potentially be used, occupational handler exposure is expected from the registered uses.  The quantitative exposure/risk assessment developed for occupational handlers is based on the following scenarios:

 Mixing/Loading for aerial application on typical and high acreage crops and aquatic uses, 
 Mixing/Loading for groundboom application on typical and high acreage crops, turf (golf courses), and orchard/vineyard, 
 Mixing/Loading for boom sprayer applications for aquatic uses, 
 Mixing/Loading for injection and spray applications for tree root control in sewer lines,
 Applying via aerial equipment on typical and high acreage crops, orchard/vineyard, and aquatic uses,
 Applying via groundboom on turf (golf course), field grown ornamentals, orchards, greenhouses, and typical and high acreage field crops,
 Applying via boom sprayer on aquatic uses, 
 Applying via mechanically-pressurized handgun on rights of way/industrial areas,
 Applying via trigger-spray bottle on foundations/perimeters, landscaping, and turf (lawns, athletic fields, parks, etc.),
 Mixing/Loading/Applying via a backpack sprayer for orchard/vineyards, greenhouse use, rights-of ways, landscaping, turf, structural areas (bridges, shipyards), industrial/commercial areas, foundations/perimeter, and aquatic areas (lakes/ponds),
 Mixing/Loading/Applying for a manually pressurized hand-wand for use in greenhouses, turf (lawns, athletic fields, parks, etc.), rights of way/industrial areas, and foundations/perimeters,
 Mixing/Loading/Applying via mechanically pressurized hand-gun for orchards (in and around trees), greenhouses, turf (golf courses), landscaping and turf (lawns, athletic fields, parks, etc.), industrial/commercial areas, and typical field crops. 
 Flagger for typical and high acreage field crops.

Occupational Handler Exposure Data and Assumptions
A series of assumptions and exposure factors served as the basis for completing the occupational handler risk assessments.  Each assumption and factor is detailed below on an individual basis.

Application Rate:  
Maximum application rates were used as noted in Table 4.1.

Unit Exposures:  
It is the policy of HED to use the best available data to assess handler exposure.  Sources of generic handler data, used as surrogate data in the absence of chemical-specific data, include PHED 1.1, the AHETF database, September 2015 revision to the Occupational Pesticide Handler Unit Exposure Surrogate Reverence Table, the November 2015 Aquatic Use SOP, the July 2015 Occupational Aquatic Assumptions or other registrant-submitted occupational exposure studies.  Some of these data are proprietary (e.g., AHETF data), and subject to the data protection provisions of FIFRA.  The standard values recommended for use in predicting handler exposure that are used in this assessment, known as "unit exposures", are outlined in the "Occupational Pesticide Handler Unit Exposure Surrogate Reference Table", which, along with additional information on HED policy on use of surrogate data, including descriptions of the various sources, can be found at the Agency website. 

Area Treated or Amount Handled:  
The inputs for area treated were based on information in ExpoSAC Policy 9.1 and based on information received from the Army Corps of Engineers (for the aquatic uses specifically).  The following summarizes the inputs used for estimating handler exposures: 

 1200 acres for aerial application to high acreage crops,
 350 acres for aerial application to typical acreage crops and orchards,
 350 acres for flaggers,
 210 acre-feet (30 acres and 7 foot depth) for boom sprayer applications to aquatic areas/lakes/ponds - submersed weeds,
 56 acre-feet (8 acres and 7 foot depth) for boom sprayer applications to aquatic areas/lakes/ponds - surface weeds,
 210 acre-feet (30 acres and 7 foot depth) for aerial applications to aquatic areas/lakes/ponds,
 200 acres for ground application to high acreage crops,
 80 acres for ground application to typical acreage crops,
 40 acres for ground applications to golf courses, ornamental crops and orchards/vineyards,
 5 acres for mechanically pressurized handgun to turf (golf courses, lawns, athletic fields, parks) and landscaping,
 1,125 gallons for injection/spray application to sewer lines, 
 1000 gallons for mechanically-pressurized handgun,  
 40 gallons for backpack and manually-pressurized handwand applications, and
 2 bottles (32-oz) for Trigger-Spray bottle treatments.
	
Exposure Duration:
HED classifies exposures from 1 to 30 days as short-term and exposures 30 days to six months as intermediate-term.  Exposure duration is determined by many things, including the exposed population, the use site, the pest pressure triggering the use of the pesticide, and the cultural practices surrounding that use site.  For most agricultural uses, it is reasonable to believe that occupational handlers will not apply the same chemical every day for more than a one-month time frame; however, there may be a large agribusiness and/or commercial applicators who may apply a product over a period of weeks (e.g., completing multiple applications for multiple clients within a region).  

For diquat dibromide, based on the registered uses, short-, and intermediate-term exposure(s) are expected for the following reasons: (1) type of application method (aquatic, ground directed defoliant/desiccant), and (2) max number of applications per year (2).

Mitigation/Personal Protective Equipment:  
Estimates of dermal and inhalation exposure were calculated for various levels of personal protective equipment (PPE). The diquat dibromide product labels direct mixers, loaders, applicators and other handlers to wear long-sleeved shirt and long pants, coveralls, shoes plus socks, chemical-resistant gloves and protective eyewear such as goggles or face shield, chemical-resistant headgear for overhead exposure, chemical resistant apron when cleaning equipment and  no respirator. However, for sewer line treatments, a dust/mist respirator (TC-21C) is required as well.

Occupational Handler Non-Cancer Exposure and Risk Estimate Equations
The algorithms used to estimate non-cancer exposure and dose for occupational handlers can be found in Appendix A.

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimates
The occupational handler non-cancer exposure and risk estimates for diquat dibromide are summarized in Table 6.1.1. There are no dermal short- or intermediate-term occupational risk estimates of concern at label specific PPE associated with the existing uses of diquat dibromide (i.e., MOEs >= 100).  Some occupational scenarios reached acceptable inhalation MOEs at baseline/label specific PPE (i.e., no respirator); however, several exposure scenarios presented risk estimates of concern (MOE < 30) at baseline/label specific PPE.   

The following scenarios reached acceptable MOEs with the addition of a PF5 respirator:
 Mixing/Loading for aerial applications to typical field crops,
 Mixing/Loading for boom sprayer applications to aquatic areas (surface weeds),
 Mixing/Loading for groundboom applications to high acreage crops, 
 Applying with groundboom to typical and high acreage field crops.
 Mixing/Loading/Applying for a backpack sprayer to rights of way and landscaping, turf/athletic fields, structural and industrial/commercial areas,
 Mixing/Loading/Applying for a mechanically-pressurized hand-wand application for the use on greenhouse ornamentals, roses, cut flowers landscaping turf, industrial and commercial areas including foundations, structural and aquatic areas.

The following scenarios reached acceptable MOEs with the addition of a PF10 respirator:
 Applying boom sprayer to aquatic areas (surface weeds),
 Applying mechanically pressurized handgun to rights of way, utilities, railroad, and roadways,
 Flagger for typical and high acreage field crops, and
 Mixing/Loading/Applying for a mechanically-pressurized hand-gun application for use in orchards (in and around trees), industrial/commercial areas, and typical field crops.
The following scenarios do not reach acceptable MOEs even with maximum PPE and EC:
 Mixing/Loading for aerial applications to high acreage crops and aquatic areas, 
 Mixer/Loader for boom sprayer applications to aquatic areas (submersed weeds) and
 Mixing/Loading/Applying for a mechanically-pressurized hand-gun application in greenhouses.

Flagger/Aerial Application:
The Agency matches quantitative occupational exposure assessment with appropriate characterization of exposure potential. While HED presents quantitative risk estimates for human flaggers where appropriate, agricultural aviation has changed dramatically over the past two decades. According the 2012 National Agricultural Aviation Association (NAAA) survey of their membership, the use of GPS for swath guidance in agricultural aviation has grown steadily from the mid 1990's. Over the same time period, the use of human flaggers for aerial pesticide applications has decreased steadily from ~15% in the late 1990's to only 1% in the most recent (2012) NAAA survey. The Agency will continue to monitor all available information sources to best assess and characterize the exposure potential for human flaggers in agricultural aerial applications.  HED has no data to assess exposures to pilots using open cockpits.  The only data available is for exposure to pilots in enclosed cockpits.  Therefore, risks to pilots are assessed using the engineering control (enclosed cockpits) and baseline attire (long-sleeve shirt, long pants, shoes, and socks); per the Agency's Worker Protection Standard stipulations for engineering controls, pilots are not required to wear protective gloves for the duration of the application. With this level of protection, there are no risk estimates of concern for applicators. 

Table 6.1.1.  Occupational Handler Non-Cancer Exposure and Risk Estimates for Diquat Dibromide.
                               Exposure Scenario
                                     Crop
                                      or 
                                    Target
                                    Dermal
                                     Unit 
                                   Exposure 
                                (μg/lb ai)[1]
                                Inhalation Unit
                            Exposure (μg/lb ai)[1]
                                     Max.
                                     App.
                                    Rate[2]
                                Area Treated /
                        Amount Handled Daily[3] (acres)
                                    Dermal
                                  Inhalation
                                       
                                       
                                  Mitigation 
                                     Level
                               Mitigation Level
                                       
                                       
                              Dose (mg/kg/day)[4]
                                    MOE[5]
                                   LOC = 100
                              Dose (mg/kg/day)[6]
                                    MOE[7]
                                   LOC = 30
                               Mixer/Loader (SC)
                                       
                                       
                                       
                                       
                                       
                                    Aerial
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                Field crop/[8]
                                    typical
                                   Label[10]
                                     29.1
                                     Label
                                     0.219
                                0.5 lb ai/acre
                                      350
                                    0.00019
                                    16,000
                                     Label
                                    0.00048
                                      8.8
                                       
                                       
                                       
                                Mitigation PF 5
                                    0.0438
                                       
                                       
                                       
                                       
                                  Mitigation 
                                     PF 5
                                   0.000096
                                      44
                                       
         Field crop, high-acreage                            (Canola/
                                   Potato -
                                 pre-harvest)
                                       
                                     Label
                                     0.219
                                       
                                     1,200
                                    0.00066
                                     4,600
                                     Label
                                    0.0016
                                      2.6
                                       
                                       
                                       
                                Mitigation PF 5
                                    0.0438
                                       
                                       
                                       
                                       
                                  Mitigation
                                      PF 5
                                    0.00033
                                      13
                                       
                                       
                                       
                               Mitigation PF 10
                                    0.0219
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 10
                                    0.00016
                                      26
                                       
                                       
                                       
                                      EC
                                     0.083
                                       
                                       
                                       
                                       
                                      EC
                                      6.7
                                    Aerial
                                 Aquatic Areas
                                     Label
                                     29.1
                                     Label
                                     0.219
                               4 lb ai/Acre-feet
                                     210 
                                   acre-feet
                                    0.00092
                                     3,300
                                    0.0023
                                      1.8
                                       
                                       
                                       
                                Mitigation PF 5
                                    0.0438
                                       
                                       
                                       
                                       
                                    0.00046
                                      9.1
                                       
                                       
                                       
                               Mitigation PF 10
                                    0.0219
                                       
                                       
                                       
                                       
                                    0.00023
                                      18
                                       
                                       
                                       
                                      EC
                                     0.083
                                       
                                       
                                       
                                       
                                   0.000871
                                      4.8
                                 Boom Sprayer
                      Aquatic areas[9] (Submersed Weeds)
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                     Label
                                     29.1
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                     Label
                                     29.1
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                     Label
                                     29.1
                                     Label
                                     0.219
                               4 lb ai/Acre-feet
                                     210 
                                  acre-feet 
                                       
                                    0.00092
                                       
                                       
                                     3,300
                                       
                                     Label
                                    0.0023 
                                      1.8
                                       
                                       
                                       
                                Mitigation PF 5
                                    0.0438
                                       
                                       
                                       
                                       
                                  Mitigation 
                                     PF 5
                                    0.00046
                                      9.1
                                       
                                       
                                       
                               Mitigation PF 10
                                    0.0219
                                       
                                       
                                       
                                       
                                  Mitigation 
                                     PF 10
                                    0.00023
                                      18
                                       
                                       
                                       
                                      EC
                                     0.083
                                       
                                       
                                       
                                       
                                      EC
                                    0.00087
                                      4.8
                                 Boom Sprayer
                         Aquatic areas (Surface Weeds)
                                       
                                     Label
                                     0.219
                               4 lb ai/Acre-feet
                                      56 
                                   acre-feet
                                   0.000245
                                       
                                    12,000
                                       
                                     Label
                                   0.000614
                                      6.8
                                       
                                       
                                       
                                Mitigation PF 5
                                    0.0438
                                       
                                       
                                       
                                       
                                       
                                  Mitigation 
                                     PF 5
                                   0.000123
                                       
                                      34
                           Mechanically Pressurized
                                    Handgun
              Rights-of-way (e.g., utilities, railroad, roadways
                                       
                                       
                                     Label
                                     0.219
                                       
                                 0.1 lb ai/gal
                                     1,000
                                      gal
                                   0.000011
                                    280,000
                                     Label
                                   0.000027
                                      150
                                       
                                Sewer Pipes[10]
                                       
                                       
                                 0.1 lb ai/gal
                                     1,125
                                      gal
                                   0.000012
                                    240,000
                                     Label
                                   0.0000062
                                      680
                                       
                                       
                                       
                                  Groundboom
                     Golf course (tees, (fairways, greens)
                                       
                                       
                                       
                                       
                                0.5 lb ai/acre
                                       
                                       
                                       
                                       
                                       
                                0.5 lb ai/acre
                                      40
                                   0.000022
                                    140,000
                                     Label
                                   0.000055
                                      77
                                       
                         Field-grown ornamental crops
                                       
                                       
                                       
                                       
                                     Label
                                     0.219
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                               Orchard/Vineyard
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                  Groundboom
                              Field crop/ typical
                                       
                                       
                                       
                                      80
                                   0.000044
                                    69,000
                                     Label
                                    0.00011
                                      38
                                       
                                  Field crop,
                                 high-acreage
                                       
                                     Label
                                     0.219
                                       
                                      200
                                    0.00011
                                    28,000
                                     Label
                                    0.00027
                                      15
                                       
                                       
                                       
                                Mitigation PF 5
                                    0.0438
                                       
                                       
                                       
                                       
                                  Mitigation 
                                     PF 5
                                   0.000055
                                      77
                                  Applicator
                                    Aerial
                              Field crop/Typical
                               Orchard/Vineyard
                                      EC
                                     2.08
                                      EC
                                    0.0049
                                0.5 lb ai/acre
                                      350
                                      EC
                                   0.000014
                                      EC
                                    220,000
                                      EC
                                   0.000011
                                      EC
                                      390
                                       
                                  Field crop,
                                 high-acreage
                                       
                                       
                                       
                                     1200
                                      EC
                                   0.000047
                                      EC
                                    64,000
                                      EC
                                   0.000037
                                      EC
                                      110
                                       
                      Aquatic areas (lakes, ponds, etc.)
                                      EC
                                     2.08
                                       
                               4 lb ai/acre-feet
                                     210 
                                   acre-feet
                                      EC
                                   0.000066
                                      EC
                                    46,000
                                      EC
                                   0.000052
                                      EC
                                      82
                                       
                                       
                                       
                                       
                                       
                                  Groundboom
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                     Golf course (fairways, tees, greens),
                         Field-grown ornamental Crops,
                               Orchard/Vineyard
                                       
                                       
                                       
                                       
                                     Label
                                     12.6
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                     Label
                                     12.6
                                       
                                       
                                     Label
                                     0.34
                                       
                                       
                                0.5 lb ai/acre
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                0.5 lb ai/acre
                                      40
                                   0.0000095
                                    320,000
                                     Label
                                   0.000085
                                       
                                      49
                                       
                                       
                              Field crop, typical
                                       
                                     Label
                                     0.34
                                       
                                      80
                                   0.000019
                                    160,000
                                     Label
                                    0.00017
                                      25
                                       
                                       
                                       
                                Mitigation PF 5
                                     0.068
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 5
                                   0.000034
                                      120
                                       
                                  Field crop,
                                  high-acreage
                                       
                                     Label
                                     0.34
                                       
                                      200
                                   0.000047
                                    63,000
                                     Label
                                    0.00043
                                      9.9
                                       
                                       
                                       
                                Mitigation PF 5
                                     0.068
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 5
                                   0.000085
                                       
                                      49
                                       
                                 Boom Sprayer
                         Aquatic areas (Surface Weeds)
                                       
                                     Label
                                     0.34
                               4 lb ai/acre-feet
                                      56
                                     acre-
                                     feet
                                   0.000106
                                       
                                    28,000
                                       
                                     Label
                                    0.0036
                                      4.4
                                       
                                       
                                       
                                  Mitigation
                                      PF5
                                     0.068
                                       
                                       
                                       
                                       
                                  Mitigation 
                                     PF 5
                                    0.00019
                                      22
                                       
                                       
                                       
                                  Mitigation
                                     PF10
                                     0.034
                                       
                                       
                                       
                                       
                                  Mitigation 
                                     PF 10
                                   0.0000953
                                       
                                      44
                                       
                           Mechanically Pressurized 
                                    Handgun
              Rights-of-way (e.g., utilities, railroad, roadways
                                     Label
                                     1,360
                                       
                                     Label
                                     8.68
                                0.01 lb ai/gal
                                     1,000
                                      gal
                                    0.00051
                                       
                                     5,900
                                       
                                     Label
                                    0.00109
                                     3.9 
                                       
                                       
                                       
                                Mitigation PF 5
                                     1.74
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 5
                                    0.00022
                                      19
                                       
                                       
                                       
                               Mitigation PF 10
                                     0.87
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 10
                                    0.00011
                                      39
                             Trigger-Spray bottle
                                    (R-T-U)
                                 Foundations/
                                   perimeter
                                     Label
                                     1,110
                                     Label
                                     61.2
                                    0.0025
                                 lb ai/bottle
                                       2
                                    bottles
                                  0.00000021
                                  14,000,000
                                     Label
                                   0.0000038
                                     1,100
                                       
            Landscaping, turf (lawns, athletic fields, parks, etc.)
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                 Flagger (SC)
                                    Aerial
                              Field crop/typical/
                                 high-acreage
                                     Label
                                     10.6
                                     Label
                                     0.35
                                     0.5 
                                  lb ai/acre
                                      350
                                   0.000070
                                    43,000
                                     Label
                                   0.000766
                                      5.5
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 5
                                   0.000154
                                      27
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 10
                                   0.000077
                                      55
                         Mixer/Loader/Applicator (SC)
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   Backpack
                                    Sprayer
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   Backpack
                                    Sprayer
                               Orchard/Vineyard
                            (Ground/soil-directed)
                                     Label
                                     4120
                                     Label
                                     2.58
                                       
                                     0.01
                                   lb ai/gal
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                    40 gal
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                    40 gal
                                       
                                   0.000062
                                    48,000
                                     Label
                                   0.0000129
                                      330
                                       
              Rights-of-way (e.g., utilities, railroad, roadways)
                                     Label
                                    16,900
                                     Label
                                     69.1
                                       
                                       
                                   0.000254
                                    12,000
                                     Label
                                   0.000345
                                      12
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 5
                                   0.000069
                                      61
                                       
            Landscaping, turf (lawns, athletic fields, parks, etc.)
                              Broadcast Treatment
                                     Label
                                    16,900
                                     Label
                                     69.1
                                       
                                     0.01
                                   lb ai/gal
                                       
                                       
                                   0.000254
                                    12,000
                                     Label
                                   0.000345
                                       
                                      12
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 5
                                   0.000069
                                       
                                      61
                                       
            Landscaping, turf (lawns, athletic fields, parks, etc.)
                                Spot Treatment 
                                     Label
                                     4,120
                                     Label
                                     2.58
                                       
                                     0.01
                                   lb ai/gal
                                       
                                       
                                   0.0000619
                                    48,000
                                     Label
                                   0.000013

                                      330
                                       
                                  Foundations
                                  /perimeter
                                     Label
                                     4,120
                                     Label
                                     2.58
                                0.04 lb ai/gal 
                                       
                                    0.00025
                                    12,000
                                     Label
                                   0.000052
                                       
                                       
                                      81
                                       
                      Aquatic areas (lakes, ponds, etc.)
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
        Structural (e.g., bridges, shipyards, home decks, foundations) 
                                     Label
                                     1600
                                     Label
                                      30
                                     0.01
                                   lb ai/gal
                                       
                                   0.000024
                                    130,000
                                     Label
                                    0.00015
                                       
                                      28
                                       
                                       
                Industrial/commercial (tires, rail/junk yards)
                                       
                                       
                                       
                                       
                                       
                                       
                                  Mitigation
                                      PF5
                                    0.00003
                                      140
                                       
                                       
                                       
                                       
                                       
                         Manually-pressurized Handwand
                                       
                                       
                                       
                                       
                                       
   Greenhouse (ornamentals, roses, cut flowers, container stock, vegetables)
                                     Label
                                      365
                                     Label
                                      30
                                0.01 lb ai/gal
                                    40 gal
                                   0.0000055
                                    550,000
                                     Label
                                    0.00015
                                      28
                                       
           Landscaping, turf, (lawns, athletic fields, parks, etc.)
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                              Indst./commercial 
                               Foundations/Prmtr
                                       
                                       
                                       
                                       
                                       
                                       
                                  Mitigation
                                      PF5
                                    0.00003
                                      140
                                       
               Structural (bridges, shipyards, home decks, etc)
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                       Mechanically-pressurized Handgun
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                       Mechanically-pressurized Handgun
                                       
                               Orchard/Vineyard
                         Drench/Soil-Ground-directed,
                    Indst./commercial,  Field crop, typical
                                     Label
                                     1,360
                                       
                                       
                                     Label
                                     8.68
                                       
                                       
                                       
                                0.01 lb ai/gal
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                0.01 lb ai/gal
                                       
                                       
                                       
                                       
                                   1000 gal
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                   1000 gal
                                       
                                       
                                    0.00051
                                       
                                     5,900
                                       
                                     Label
                                    0.00109
                                       
                                      3.9
                                       
                                       
                                       
                                  Mitigation
                                     PF 5
                                     1.74
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 5
                                   0.000218
                                      19
                                       
                                       
                                       
                                  Mitigation
                                     PF 10
                                     0.87
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 10
                                    0.00011
                                      39
                                       
   Greenhouse (ornamentals, roses, cut flowers, container stock, vegetables)
                         Drench/Soil-/Ground-directed
                                     Label
                                     1,600
                                     Label
                                      120
                                       
                                       
                                    0.00060
                                     5,000
                                     Label
                                     0.015
                                     0.28
                                       
                                       
                                       
                                  Mitigation
                                     PF 5
                                      24
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 5
                                     0.003
                                      1.4
                                       
                                       
                                       
                                  Mitigation
                                     PF 10
                                      12
                                       
                                       
                                       
                                       
                                  Mitigation
                                     PF 10
                                    0.0015
                                      2.8
                                       
                     Golf course, (tees fairways, greens)
                                     Label
                                      450
                                     Label
                                      1.9
                                0.5 lb ai/Acre
                                    5 acres
                                   0.000042
    71,000
                                     Label
                                   0.0000594
                                      71
                                       
            Landscaping, turf (lawns, athletic fields, parks, etc.)
                                       
                                       
                                       
                                       
                                       
                                       
                                       
                                       
1	Based on the "Occupational Pesticide Handler Unit Exposure Surrogate Reference Table" (September. 2015); Mitigation: Level of PPE above what is currently required on the labels needed to achieve a MOE = 30 for inhalation exposure.  The diquat dibromide product labels direct mixers, loaders, applicators and other handlers to wear long-sleeved shirt and long pants, coveralls, shoes  plus socks, chemical-resistant gloves and protective eyewear such as goggles or face shield, chemical-resistant headgear for overhead exposure, chemical resistant apron when cleaning equipment and  no respirator. However, sewer line treatments call for a dust/mist respirator as well.
2	Based on Table 4.1
3	Exposure Science Advisory Council Policy #9.0., Draft Occupational Aquatic Assumptions: July 2015 and the Aquatic SOP: November 2015.  Aquatic scenario inputs based on personal communication with Kurt Getsinger, U.S. Army Engineer R&D Center (July 25, 2016).
4	Dermal Dose = Dermal Unit Exposure (μg/lb ai) x Conversion Factor (0.001 mg/μg) x Application Rate (lb ai/acre or gal) x Area Treated or Amount  Handled Daily (A or gal/day) x DAF (0.3 %) / BW (80 kg).
5	Dermal MOE = Dermal NOAEL (3 mg/kg/day) / Dermal Dose (mg/kg/day).
6	Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) x Conversion Factor (0.001 mg/μg) x Application Rate (lb ai/acre or gal) x Area Treated or Amount  Handled Daily (A or gal/day) / BW (80 kg).
7	Inhalation MOE = Inhalation human equivalent dose (0.0042 mg/kg/day) / Inhalation Dose (mg/kg/day).  
8. Field Crop/Typical: Carrots, Coriander, Radishes, Spinach, Sugar beets, Table Beets, Turnips, Calendula, Tomato Vines, Cantaloupe Vines, Cucumbers, Squash, Watermelon Vines, Acorn Squash, Peppers, Eggplant, Green Pepper, Tomato, Green Peppers, Tomatoes
9.  The maximum single application rate of 4 lb ai/Acre/1 ft. for aerial applications is the most conservative aquatic (floating and marginal weeds) use rate. Based on the conversation with PRD and BEAD (7.28.2016), updates were made to the occupational scenarios for the aquatic uses:   Aquatic areas (Submersed Weeds) area treated = 210 acre-feet, and for Aquatic areas (Surface Weeds) area treated = 56 acre-feet (8 acres and 7 foot depth) based on the info from the US Army Corps of Engineers.
10. Label (EPA Reg. No. 64898-8;Razorooter II(TM)) notes that applications for spraying into sewer pipes consists of inserting a hose "downstream," then retracting the hose while turned on or spraying. Therefore, an applicator exposure scenario was not assessed.  For the amount of gallons approximated, see Memorandum, DP # 357118 titled, Metam Sodium: Third Revision of the HED Human Risk Assessment, Dated April 30, 2009.


6.2	Occupational Post-application Exposure/Risk Estimates

HED uses the term post-application to describe exposures that occur when individuals are present in an environment that has been previously treated with a pesticide (also referred to as re-entry exposure).  Such exposures may occur when workers enter previously treated areas to perform job functions, including activities related to crop production, such as scouting for pests or harvesting.  In the case of post-harvest treatment, post application activities include sorting and packing the treated crop. Post-application exposure levels vary over time and depend on such things as the type of activity, the nature of the crop or target that was treated, the type of pesticide application, and the chemical's degradation properties. 
 
6.2.1	Occupational Post-application Inhalation Exposure / Risk Estimates

Occupational Post-application Inhalation Exposure Data and Assumptions
There are multiple potential sources of post-application inhalation exposure to individuals performing post-application activities in previously treated fields. These potential sources include volatilization of pesticides and re-suspension of dusts and/or particulates that contain pesticides.  The agency sought expert advice and input on issues related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, and received the SAP's final report on March 2, 2010 (http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html).  The agency has evaluated the SAP report and has developed a Volatilization Screening Tool and a subsequent Volatilization Screening Analysis (http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219).  During Registration Review, the agency will utilize this analysis to determine if data (i.e., flux studies, route-specific inhalation toxicological studies) or further analysis is required for diquat dibromide.

In addition, the Agency is continuing to evaluate the available post-application inhalation exposure data generated by the Agricultural Reentry Task Force.  Given these two efforts, the Agency will continue to identify the need for and, subsequently, the way to incorporate occupational post-application inhalation exposure into the agency's risk assessments.

6.2.2	Occupational Post-application Dermal Exposure/Risk Estimates

Occupational Post-application Dermal Exposure Data and Assumptions
HED believes that due to the nature of the chemical (herbicide) and the exposure scenarios; pre-, and post-harvest desiccant/de-foliar; ground directed spray for the control of weeds and aquatic uses, a quantitative occupational post-application dermal exposure assessment was not warranted for these uses. However, a dermal post-application assessment was completed for the registered golf course turf uses to cover exposure from workers performing maintenance to golf courses post turf applications.

A series of assumptions and exposure factors served as the basis for completing the occupational post-application risk assessments.  Each assumption and factor is detailed below on an individual basis.

Exposure Duration: 
HED classifies exposures from 1 to 30 days as short-term and exposures 30 days to six months as intermediate-term. For diquat dibromide, based on the proposed use, dermal exposure due to applications to golf course turf are expected for the following reasons:  (1) Post turf applications, workers will be conducting maintenance to fairways and greens. Due to the maximum number of applications per year (3), HED believes that the exposure will be short-term in nature. However, due to the short-, and intermediate-term PODs being the same, an intermediate assessment was included.

Transfer Coefficients: 
It is the policy of HED to use the best available data to assess post-application exposure.  Sources of generic post-application data, used as surrogate data in the absence of chemical-specific data, are derived from ARTF exposure monitoring studies, and, as proprietary data, are subject to the data protection provisions of FIFRA.  The standard values recommended for use in predicting post-application exposure that are used in this assessment, known as "transfer coefficients",  are presented in the ExpoSAC Policy 3" which, along with additional information about the ARTF data, can be found at the Agency website.  Table 6.2.2.1 provides a summary of the anticipated post-application activities and associated transfer coefficients for the proposed crops/use sites

Table 6.2.2.1.  Anticipated Post-Application Activities and Dermal Transfer Coefficients.
                                Proposed Crops
                          Policy Crop Group Category
                                  Crop Height
                                Foliage Density
                       Transfer Coefficients (cm[2]/hr)
                                  Activities
                                  Golf course
                                  Turf/sod[1]
                                      low
                                     full
                                     3700
                                  Maintenance
                                       
                                       
                                       
                                       
                                     2500
                            Maintenance/greens only
1. No crop category is assigned for turf/sod

Application Rate: 
See the use profile table 4.1 for details.

Exposure Time:  
The average occupational workday is assumed to be 8 hours. 

Dislodgeable Foliar Residues:  
Chemical-specific dislodgeable foliar residue "turf" data has been submitted for diquat dibromide. However, the Modified California Roller method was not used for data gathering, therefore, this assessment uses HED's default assumption that 1% of the application is available for transfer on day 0 following the application and the residues dissipate at a rate of 10% each following day.

Occupational Post-application Non-Cancer Dermal Exposure and Risk Estimate Equations
The algorithms used to estimate non-cancer exposure and dose for occupational post-application workers can be found in Appendix A.

Occupational Post-application Non-Cancer Dermal Risk Estimates

Table 6.2.2.2.  Occupational Post-application Non-Cancer Exposure and Risk Estimates for Diquat Dibromide.
                                   Crop/Site
                                  Activities
                        Transfer Coefficient (cm[2]/hr)
                                  DFR/TTR[1]
                                 Dermal Dose 
                                (mg/kg/day)[2]
                                    MOE[3]
                         Short-term/ Intermediate-term
                                     Turf:
                                       
                                  Golf Course
                                  Maintenance
                                     3700
                                     0.056
                                       
                                     0.056
                                   0.000062
                                    48,000
                                       
                            Maintenance/greens only
                                     2500
                                       
                                   0.000042
                                    71,000
1	TTR = Application Rate x F x (1-D)t x 4.54E8 ug/lb x 2.47E-8 acre/cm[2]; where F = 0.1 and D = 0.10 per 
2	Daily Dermal Dose = [DFR (ug/cm[2]) x Transfer Coefficient x 0.001 mg/ug x 8 hrs/day x dermal absorption (0.3 %)]  BW (80 kg).
3	MOE = POD (mg/kg/day) / Daily Dermal Dose.  Daily Dermal Dose = [DFR/TTR (ug/cm[2]) x TC x 0.001 mg/ug x 8 hrs/day x dermal absorption factor (0.3 %)]  BW (80 kg).

Restricted Entry Interval
Diquat dibromide is classified as Acute Toxicity Categories II or III via the oral, dermal, and inhalation routes.  . Diquat dibromide is not an acute skin irritant (Toxicity Category IV) nor a dermal sensitizer, but it is considered a moderate-to-severe eye irritant (Toxicity Category II).  Short- and intermediate-term post-application risk estimates were not a concern on day 0 (12 hours following application) for all post-application activities. The current product labels recommend a 24-hour REI.

Appendix A.  Summary of Residential and Occupational and Non-cancer Algorithms

 Residential Handlers Dermal and Inhalation Handler Exposure Algorithm
1.1	Turf, Gardens and Trees, Indoor Environments
Daily dermal and inhalation exposure (mg/day) for residential pesticide handlers, for a given formulation-application method combination, is estimated by multiplying the formulation-application method-specific unit exposure by an estimate of the amount of active ingredient handled in a day, using the equation below:

                                E = UE * AR * A
Where:

E 	= exposure (mg/day);
UE 	= unit exposure (mg/lb ai);
AR 	= application rate (e.g., lb ai/ft[2], lb ai/gal); and
A 	= area treated or amount handled (e.g., ft[2]/day, gal/day).


1.2	Residential Handler Dose Calculations

Dermal and/or inhalation absorbed doses normalized to body weight are calculated as:

                                D = E *AF / BW
Where:

D 	= dose (mg/kg-day);
E 	= exposure (mg/day);
AF 	= absorption factor (dermal and/or inhalation); and
BW	 = body weight (kg).


2.0	Residential Non-cancer Post-application Algorithms
2.1	Turf/Physical Activities on Turf

Post-application Dermal Exposure Algorithm  -  Physical Activities on Turf
Exposure resulting from contacting previously treated turf while performing physical activities is calculated as shown below.  Residential post-application exposure assessment must include calculation of exposure on the day of application.  Therefore, though an assessment can present exposures for any day "t" following the application, it must include "day 0" exposure.

                           E = TTRt * CF1 * TC * ET
Where:

E 	= exposure (mg/day);
TTRt 	= turf transferable residue on day t (μg/cm[2]);
CF1 	= weight unit conversion factor (0.001 mg/μg);
TC	 = transfer coefficient (cm[2]/hr); and
ET	 = exposure time (hr/day).

If chemical-specific TTR data are available, then surface residues from the day of application should be used (assume that individuals could be exposed to residues immediately after application). However, if data are not available, then TTRt can be calculated using the following formula:

                      TTRt= AR * F * (1-FD)t * CF2 * CF3
Where:

TTRt 	= turf transferable residue on day t (μg/cm[2]);
AR 	= application rate (lbs ai/ft[2] or lb ai/acre);
F 	= fraction of ai as transferable residue following application (unitless);
FD 	= fraction of residue that dissipates daily (unitless);
t 	= post-application day on which exposure is being assessed;
CF2	= weight unit conversion factor (4.54 x 10[8] μg/lb); and
CF3 	= area unit conversion factor (1.08 x 10[-3] ft[2]/ cm[2] or 2.47 x 10[-8] acre/cm[2]).

Dermal absorbed doses are calculated as:
	 	
Where:

D	= dose (mg/kg-day);
E	= exposure (mg/day);
AF	= absorption factor (dermal); and
BW	= body weight (kg).

Turf (Physical Activities) -- Inputs for Residential Post-application Dermal Exposure
                              Algorithm Notation
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
                                      AR
                               Application rate
                    (mass active ingredient per unit area)
                                    [input]
                                       F
Fraction of AR as TTR following application (if chemical-specific data is unavailable)
                                   L/WP/WDG
                                     0.01
                                       
                                       
                                   Granules
                                     0.002
                                      FD
     Daily residue dissipation (if chemical-specific data is unavailable)
                                  (fraction)
                                   L/WP/WDG
                                      0.1
                                       
                                       
                                   Granules
                                      0.1
                                      TC
                        Transfer Coefficient (cm[2]/hr)
                                   L/WP/WDG
                                    Adults
                                    180,000
                                       
                                       
                                       
                          Children 1 < 2 years old
                                    49,000
                                       
                                       
                                   Granules
                                    Adults
                                    200,000
                                       
                                       
                                       
                          Children 1 < 2 years old
                                    54,000
                                      ET
                                 Exposure Time
                                (hours per day)
                                    Adults
                                      1.5
                                       
                                       
                          Children 1 < 2 years old
                                      1.5
                                      BW
                                  Body Weight
                                     (kg)
                                    Adults
                                      80
                                       
                                       
                          Children 1 < 2 years old
                                      11
L/WP/WDG = Liquids/Wettable Powders/Water-dispersible Granules

Post-application Hand-to-Mouth Exposure Algorithm -  Physical Activities on Turf
Exposure from hand-to-mouth activity is calculated as follows (based on the algorithm utilized in the SHEDS-Multimedia model):

  E = [HR * (FM * SAH) * (ET * N_Replen) * (1- (1- SE)[(Freq_HtM/N-Replen)])]
Where:

E 	= exposure (mg/day);
HR	 = hand residue loading (mg/cm[2]);
FM 	= fraction hand surface area mouthed / event (fraction/event);
SAH 	= typical surface area of one hand (cm[2]);
ET 	= exposure time (hr/day);
N_Replen = number of replenishment intervals per hour (intervals/hour);
SE 	= saliva extraction factor (i.e., mouthing removal efficiency); and
Freq_HtM = number of hand-to-mouth contacts events per hour (events/hour).

		
Where:

HR 	= hand residue loading (mg/cm[2]);
Faihands	= fraction ai on hands compared to total surface residue from dermal transfer coefficient                study (unitless);
DE 	= dermal exposure (mg); and
SAH	= typical surface area of one hand (cm[2]).

Dose, normalized to body weight, is calculated as:

	 	
Where:
D	= dose (mg/kg-day);
E	= exposure (mg/day); and
BW	= body weight (kg).



Turf (Physical Activities)  -  Inputs for Residential Post-application Hand-to-Mouth Exposure 
                              Algorithm Notation
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
                                   Faihands
        Fraction of ai on hands from dermal transfer coefficient study
                                  (unitless)
                              Liquid formulations
                                     0.06
                                       
                                       
                             Granular formulations
                                     0.027
                                      DE
                             Dermal exposure (mg)
                                  Calculated
                                      SAH
     Typical surface area of one hand (cm[2]), children 1 < 2 years old
                                      150
                                      AR
                               Application rate
                    (mass active ingredient per unit area)
                                    [input]
                                      HR
                   Residue available on the hands (mg/cm[2])
                      Calculated via (DE * Faihands)/SAH
                                      FM
                      Fraction hand surface area mouthed
                               (fraction/event)
                                     0.127
                                   N_Replen
                       Replenishment intervals per hour
                                (intervals/hr)
                                       4
                                      ET
                                Exposure time 
                                   (hrs/day)
                                      1.5
                                      SE
                           Saliva extraction factor
                                  (unitless)
                                     0.48
                                   Freq_HtM
                         Hand-to-mouth events per hour
                                  (events/hr)
                                     13.9
                                      BW
                                  Body Weight
                                     (kg)
                          Children 1 < 2 years old
                                      11

Post-application Object-to-Mouth Exposure Algorithm -  Physical Activities on Turf
Exposure from object-to-mouth activity is calculated as follows (based on the algorithm utilized in SHEDS-Multimedia):
                                       	
	E = [OR* CF1 * SAMO * (ET * N_Replen) * (1- (1- SEO)(Freq_OtM/N_Replen))]	

Where:

E	= exposure (mg/day);
OR	= chemical residue loading on the object on day "t" (ug/cm[2]);
CF1 	= weight unit conversion factor (0.001 mg/ug);
SAMO 	= area of the object surface that is mouthed (cm[2]/event);
ET 	= exposure time (hr/day);
N_Replen = number of replenishment intervals per hour (intervals/hour);
SEO  	= saliva extraction factor (i.e., mouthing removal efficiency); and
Freq_OtM  = number of object-to-mouth contact events per hour (events/hour).

	OR = AR * FO * CF2 * CF3 	
Where:

OR 	= chemical residue loading on the object (μg/cm[2]);
AR 	= application rate (lbs ai/ft[2] or lb ai/acre);
FO 	= fraction of residue available on the object (unitless);
CF2 	= weight unit conversion factor (4.54 x 10[8] ug/lb); and
CF3 	= area unit conversion factor (1.08 x 10[-3] ft[2]/cm[2] or 2.47 x 10[-8] acre/cm[2]).

Dose, normalized to body weight, is calculated as:

	 	
Where:
D	=	dose (mg/kg-day);
E	= exposure (mg/day); and
BW	= body weight (kg).

Turf (Physical Activities)  -  Inputs for Residential Post-application Object-to-Mouth Exposure 
                              Algorithm Notation
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
                                      AR
                          Application rate (to turf)
                    (mass active ingredient per unit area)
                                    [input]
                                      FO
                Fraction of AR as OR following application [1]
                                     0.01
                                     SAMO
                        Surface area of object mouthed 
                                 (cm[2]/event)
                                      10
                                   N_Replen
               Replenishment intervals per hour (intervals/hour)
                                       4
                                      SEO
                           Saliva extraction factor
                                  (fraction)
                                     0.48
                                      ET
                                Exposure time 
                                (hours per day)
                                      1.5
                                   Freq_OtM
                  Object-to-mouth events per hour (events/hr)
                                      8.8
                                      BW
                               Body Weight (kg)
                          Children 1 < 2 years old
                                      11
1 This SOP assumes that all of the residue on the turf could be transferred to the object (e.g., object residue is equal to turf transferable residue).

Post-application Incidental Soil Ingestion Exposure Algorithm -  Physical Activities on Turf
Exposure from incidental soil ingestion is calculated as follows:

	E = SRt * SIgR * CF1 	
Where:

E 	= exposure (mg/day);
SRt	= soil residue on day "t" (ug/g);
SIgR	= ingestion rate of soil (mg/day); and
CF1 	= weight unit conversion factor (1 x 10[-6] g/ug).

	SRt = AR * FS * (1-FD)t * CF2 * CF3 * CF4 	
Where:

SRt 	= soil residue on day "t" (ug/g);
AR 	= application rate (lbs ai/ft[2] or lb ai/acre);
FS 	= fraction of ai available in uppermost cm of soil (fraction/cm);
FD	 = fraction of residue that dissipates daily (unitless);
T 	= post-application day on which exposure is being assessed;
CF2	= weight unit conversion factor (4.54 x 10[8] ug/lb);
CF3 	= area unit conversion factor (1.08 x 10[-3] ft[2]/cm2 or 2.47 x 10[-8] acre/cm[2]); and
CF4	 = soil volume to weight unit conversion factor (0.67 cm[3]/g soil).

Dose, normalized to body weight, are calculated as:

	 	
Where:
D	= dose (mg/kg-day);
E	= exposure (mg/day); and
BW	= body weight (kg).


Turf (Physical Activities)  -  Inputs for Residential Post-application Incidental Soil Ingestion Exposure 
                              Algorithm Notation
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
                                      AR
                               Application rate
                    (mass active ingredient per unit area)
                                    [input]
                                      FS
              Fraction of AR available in uppermost 1 cm of soil
                                  (unitless)
                                       1
                                      FD
                           Daily residue dissipation
                                  (fraction)
                                      0.1
                                     SIgR
                         Soil ingestion rate (mg/day)
                                      50
                                      BW
                               Body weight (kg)
                          Children 1 < 2 years old
                                      11

Post-application Episodic Granular Ingestion Exposure Algorithm -  Physical Activities on Turf
Exposure from incidental ingestion of pesticide pellets or granules is calculated as follows:

               	                     		E = GIgR* FD * CF1						
Where:

E 	= exposure (mg/day);
GIgR 	= ingestion rate of dry pesticide formulation (g/day);
FD 	= fraction of ai in dry formulation (unitless); and
CF1 	= weight unit conversion factor (1,000 mg/g).

Dose, normalized to body weight, are calculated as:

		
Where:
D	= dose (mg/kg-day);
E	= exposure (mg/day); and
BW	= body weight (kg).
2.2	Turf/Mowing

Post-application Dermal Exposure Algorithm  -  Mowing
Exposure resulting from contacting previously treated turf while mowing is calculated as follows:

	E = TTRt * CF1 * TC * ET 	
Where:

E 	= exposure (mg/day);
TTRt  	= turf transferable residue on day "t" (ug/cm[2]);
CF1	 = weight unit conversion factor (0.001 mg/ug);
TC  	= transfer coefficient (cm[2]/hr); and
ET  	= exposure time (hr/day).

	TTRt = AR * FAR * (1-FD)t * CF2 * CF3 	
Where:

TTRt  	= turf transferable residue on day "t" (ug/cm[2]);
AR 	= application rate (lbs ai/ft[2] or lb ai/acre);
FAR	= fraction of ai retained on turf (unitless);
FD 	= fraction of residue that dissipates daily (unitless);
T	= post-application day on which exposure is being assessed;
CF2	= weight unit conversion factor (4.54 x 10[8] ug/lb); and
CF3 	= area unit conversion factor (1.08 x 10[-3] ft[2]/cm[2] or 2.47 x 10[-8] acre/cm[2]).

Absorbed dose, normalized to body weight, are calculated as:

                                       
Where:
D	= dose (mg/kg-day);
E	= exposure (mg/day); 
AF	= absorption factor (dermal); and
BW	= body weight (kg).

Turf (Mowing)  -  Inputs for Residential Post-application Dermal Exposure 
                              Algorithm Notation
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
                                      AR
                               Application rate
                     mass active ingredient per unit area
                                    [input]
                                      FAR
                  Fraction of AR as TTR following application
                                   L/WP/WDG
                                     0.01
                                       
                                       
                                   Granules
                                     0.002
                                      FD
                           Daily residue dissipation
                                   L/WP/WDG
                                      0.1
                                       
                                       
                                   Granules
                                      0.1
                                      TC
                             Transfer Coefficient
                                  (cm[2]/hr)
                                     Adult
                                     5,500
                                       
                                       
                         Children 11 < 16 years old
                                     4,500
                                      ET
                                Exposure time 
                                (hours per day)
                                       1
                                      BW
                                 Body Weight 
                                     (kg)
                                    Adults
                                      80
                                       
                                       
                         Children 11 < 16 years old
                                      57
L/WP/WDG = liquid/wettable powder/water dispersible granule


2.3	Turf/Golfing

Post-application Dermal Exposure Algorithm  -  Golfing
Exposure resulting from contacting previously treated turf while golfing is calculated as follows:

	E = TTRt * CF1 * TC * ET 	
Where:

E	= exposure (mg/day); 
TTRt 	= turf transferable residue on day "t" (ug/cm[2]);
CF1	= weight unit conversion factor (0.001 mg/ug);
TC	= transfer coefficient (cm[2]/hr); and
ET 	= exposure time (hr/day).

	TTRt = AR * F * (1-FD)t * CF2 * CF3 	
Where:

TTRt	= turf transferable residue on day "t" (ug/cm[2]);
AR 	= application rate (lbs ai/ft[2] or lb ai/acre);
F 	= fraction of ai retained on turf (unitless);'
FD 	= fraction of residue that dissipates daily (unitless);
T	= post-application day on which exposure is being assessed;
CF2	= weight unit conversion factor (4.54 x 10[8] ug/lb); and
CF3 	= area unit conversion factor (1.08 x 10[-3] ft[2]/cm[2] or 2.47 x 10[-8] acre/cm[2]).

Absorbed dose, normalized to body weight, is calculated as:

	 	
Where:
D	= dose (mg/kg-day);
E	= exposure (mg/day); 
AF	= absorption factor (dermal); and
BW	= body weight (kg).


Turf (Golfing)  -  Inputs for Residential Post-application Dermal Exposure 
                              Algorithm Notation
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
                                       
                                       
                                       
                                      AR
                               Application rate
                    (mass active ingredient per unit area)
                                    [input]
                                       F
                  Fraction of AR as TTR following application
                                   L/WP/WDG
                                     0.01
                                       
                                       
                                   Granules
                                     0.002
                                      FD
                           Daily residue dissipation
                                   L/WP/WDG
                                      0.1
                                       
                                       
                                   Granules
                                      0.1
                                      TC
                             Transfer Coefficient
                                  (cm[2]/hr)
                                     Adult
                                     5,300
                                       
                                       
                         Children 11 < 16 years old
                                     4,400
                                       
                                       
                         Children 6 < 11 years old
                                     2,900
                                      ET
                                 Exposure time
                                (hours per day)
                Pesticides used on greens, tees, and fairways 
                                       4
                                       
                                       
                    Pesticides used only on greens and tees
                                       1
                                      BW
                                  Body Weight
                                     (kg)
                                    Adults
                                      80
                                       
                                       
                         Children 11 < 16 years old
                                      57
                                       
                                       
                         Children 6 < 11 years old
                                      32
NA = not applicable
L/WP/WDG = liquid/wettable powder/water dispersible granule


2.4	Gardens and Trees

Post-application Dermal Exposure Algorithm
Exposure resulting from contacting previously treated gardens and trees while performing physical activities is calculated as shown below.  Residential post-application exposure assessment must include calculation of exposure on the day of application.  Therefore, though an assessment can present exposures for any day "t" following the application, it must include "day 0" exposure.
	E = DFRt * CF1 * TC * ET 
	
Where:

E 	= exposure (mg/day);
DFRt 	= dislodgeable foliar residue on day "t" (ug/cm[2]);
CF1	= weight unit conversion factor (0.001 mg/ug);
TC	= transfer coefficient (cm[2]/hr); and
ET 	= exposure time (hrs/day).

In the absence of chemical-specific data, DFRt can be calculated as follows:

	DFRt = AR * FAR * (1-FD)t * CF2 * CF3 	
Where:

DFRt 	= dislodgeable foliar residue on day "t" (ug/cm[2]);
AR	= application rate (lbs ai/ft[2] or lb ai/acre);
FAR	= fraction of ai as dislodgeable residue following application (unitless);
FD 	= fraction of residue that dissipates daily (unitless);
T	= post-application day on which exposure is being assessed;
CF2 	= weight unit conversion factor (4.54 x 10[8] ug/lb); and
CF3	= area unit conversion factor (1.08 x 10[-3] ft[2]/cm[2] or 2.47 x 10[-8] acre/cm[2]).

Absorbed dermal dose, normalized to body weight, is calculated as:

	 	
Where:

D	= dose (mg/kg-day);
E	= exposure (mg/day);
AF	= absorption factor (dermal and/or inhalation); and
BW	= body weight (kg).

Gardens, Trees, and "Pick-your-own" Farms  - Inputs for Residential Post-application Dermal Exposure 
                              Algorithm Notation
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
                                       
                                      AR
                   Application rate (mass ai per unit area)
                                    [input]
                                      FAR
   DFR following application, if chemical-specific is unavailable (fraction)
                                     0.25
                                      FD
   Daily residue dissipation, if chemical-specific is unavailable (fraction)
                                     0.10
                                      TC
                             Transfer Coefficient
                                  (cm[2]/hr)
                                  Gardens[a]
                                    Adults
                                     8400
                                       
                                       
                                       
                         Children 6 < 11 years old
                                     4600
                                       
                                       
                    Trees, Retail Plants (if applicable)[a]
                                    Adults
                                     1700
                                       
                                       
                                       
                         Children 6 < 11 years old
                                      930
                                       
                                       
                                 Indoor Plants
                                    Adults
                                      220
                                       
                                       
                                       
                         Children 6 < 11 years old
                                      120
                                      ET
                                 Exposure Time
                                (hours per day)
                              Home activities[b]
                                    Gardens
                                    Adults
                                      2.2
                                       
                                       
                                       
                                       
                         Children 6 < 11 years old
                                      1.1
                                       
                                       
                                       
                     Trees, Retail Plants (if applicable)
                                    Adults
                                      1.0
                                       
                                       
                                       
                                       
                         Children 6 < 11 years old
                                     0.50
                                       
                                       
                                       
                                 Indoor Plants
                                    Adults
                                      1.0
                                       
                                       
                                       
                                       
                         Children 6 < 11 years old
                                     0.50
                                       
                                       
                   "Pick-your-own" Farms (if applicable)
                                    Adults
                                      5.0
                                       
                                       
                                       
                         Children 6 < 11 years old
                                      1.9
                                      BW
                                  Body weight
                                     (kg)
                                    Adults
                                      80
                                       
                                       
                         Children 6 < 11 years old
                                      32
[a] Transfer coefficient point estimates from a composite distribution assuming equal proportion of time spent conducting various activities.  See "Transfer Coefficient" section below.  Children 6 < 11 years old TC derived using surface area adjustment (see Section 2.3).
[b] Activity time point estimates from a composite distribution assuming equal proportion of each respective activity.  Time for children 6 < 11 years old derived using hrs/day ratio adjustment.  See "Exposure Time" section below. 
3.0	Occupational Handlers

Occupational Non-cancer Handler Algorithms

Potential daily exposures for occupational handlers are calculated using the following formulas:

E=UE * AR * A * 0.001 mg/ug
Where:

E	= exposure (mg ai/day),
UE	= unit exposure (ug ai/lb ai),
AR	= maximum application rate according to proposed label (lb ai A or lb ai/gal), and
A	= area treated or amount handled (e.g., A/day, gal/day).
 
The daily doses are calculated using the following formula:

ADD=  E * AFBW
Where:

ADD	= average daily dose absorbed in a given scenario (mg ai/kg/day),
E	= exposure (mg ai/day),
AF	= absorption factor (dermal and/or inhalation), and
BW 	= body weight (kg).

Margin of Exposure:  Non-cancer risk estimates for each application handler scenario are calculated using a Margin of Exposure (MOE), which is a ratio of the toxicological endpoint to the daily dose of concern.  The daily dermal and inhalation dose received by occupational handlers are compared to the appropriate POD (i.e., NOAEL) to assess the risk to occupational handlers for each exposure route.  All MOE values are calculated using the following formula:

MOE= PODADD

Where:

MOE	= margin of exposure: value used by HED to represent risk estimates (unitless),
POD	= point of departure (mg/kg/day), and
ADD	= average daily dose absorbed in a given scenario (mg ai/kg/day).


4.0	Occupational Post-Application

Occupational Non-cancer Post-application Algorithms

Potential daily exposures for occupational post-application workers are calculated using the following formulas:
DFRt=AR *  F* (1-D)t*4.54E8uglb*2.47E-8Acm2
Where:

DFRt	= dislodgeable foliage residue on day "t" (ug/cm[2]),
AR	= application rate (lb ai/acre),
F	= fraction of ai retained on foliage or 25% (unitless),
D	= fraction of residue that dissipates daily or 10% (unitless), and
t	= number of days after application day (days).

E=TC * DFR t * ET * 0.001mgug
Where:

E	= exposure (mg ai/day),
TC 	= transfer coefficient (cm[2]/hr),
DFRt	= dislodgeable foliar residue on day "t" (ug/cm[2]), and
ET	= exposure time (hours/day).
 
The daily doses are calculated using the following formula:

ADD=  E * AFBW
Where:

ADD	= average daily dose absorbed in a given scenario (mg ai/kg/day),
E	= exposure (mg ai/day),
AF	= absorption factor (dermal and/or inhalation), and
BW 	= body weight (kg).
Margin of Exposure:  Non-cancer risk estimates for each scenario are calculated using a Margin of Exposure (MOE), which is a ratio of the toxicological endpoint to the daily dose of concern.  The daily dermal dose received by occupational post-application workers is compared to the appropriate POD (i.e., NOAEL) to assess the risk to occupational post-application workers.  All MOE values are calculated using the following formula:
MOE= PODADD
Where:

MOE	= margin of exposure: value used by HED to represent risk estimates (unitless),
POD	= point of departure (mg/kg/day), and
ADD	= average daily dose absorbed in a given scenario (mg ai/kg/day).

5.0	Aquatic Use

The procedures outlined in this section should be used to assess residential dermal and inhalation exposure during (i.e., handler) and following (i.e., post-application) pesticide applications to aquatic areas, such as lakes and ponds by professional pesticide applicators or homeowners themselves.  Pesticides can also be used in pools and spas which can lead to both residential handler and post-application exposure.  The Antimicrobials Division (AD) of OPP has guidance and SOPs for assessing exposure from treated pools and spas, including the Swimmer Exposure Assessment Model (http://www.epa.gov/oppad001/swimodel.htm).

For pesticides that can be used in aquatic areas such as lakes and ponds, the exposure assessor should assume the product is permitted for use by homeowners unless: 
 The product has a "Restricted Use Pesticide" classification, which indicates that the product cannot be bought or applied by homeowners (i.e., no residential handler exposure/risk assessment required).  
 The label indicates that the product may only be applied to water by Federal or State agencies, U.S. Army Corps of Engineers, and licensed applicators authorized by Federal or State agencies.
 The labels indicate state and/or local authorities are to be consulted prior to applying this product in or around public waters.
 The labels state that prior to retreatment, samples should be collected and analyzed for parent concentration to establish the amount of product to apply.

In each of these cases, a residential handler assessment would not be necessary, but the product may be applied by commercial applicators to residential sites; therefore, a post-application risk assessment may be required.   The post-application section of this SOP typically will apply to situations where an application is made by commercial applicators to larger aquatic areas (e.g., lakes, ponds) where swimming would be expected to occur.  It is not anticipated that swimming would occur in aquatic areas typically assumed to be treated by homeowners, such as backyard ponds or fountains.  Once scenarios are identified, the assessment should then characterize and estimate the potential for exposure by route (e.g., dermal, inhalation, oral) using the methodologies outlined in this section.

In certain circumstances, it may be appropriate to assess dermal and incidental oral exposure to sediment (e.g., application of a pesticide to intertidal waters or oyster beds), however, this should not routinely be conducted for typical aquatic applications.  If such assessments are deemed necessary, the assessor should refer to recent example assessments such as those for imidacloprid (D400191) or carbaryl (D287251).

5.1	Handler Exposure Assessment

Handler exposure can result from treating aquatic sites in residential settings (e.g., backyard ponds or fountains) with pesticides.  Some key assumptions for these assessments include:

 Adults are considered the index lifestage for this scenario as it is assumed that pesticides are applied by adults only (i.e., individuals 16 years and older).
 All application equipment and methods are assumed feasible unless prohibited by the product label.


Dermal and Inhalation Handler Exposure Algorithm
As described, daily dermal and inhalation exposure (mg/day) for residential pesticide handlers, for a given formulation-application method combination, is estimated by multiplying the formulation-application method-specific unit exposure by an estimate of the amount of active ingredient handled in a day, using the equation below:

E=UE*AR*A*D
Where:

E	= exposure (mg/day);
UE	= unit exposure (mg/lb ai);
AR	= application rate (e.g., lb ai/ft2, lb ai/ft3, lb ai/A-ft); 
A	= area treated (e.g., ft[2]/day, A/day); and
D	= depth of water body treated (ft).

NOTE:  The input for the depth of the water body treated is only applicable if the application rate is given per volume (i.e., lb ai/ft[3] or lb ai/A-ft).

Dermal and/or inhalation absorbed doses normalized to body weight are calculated as:

D= E*AFBW
Where:

D	= dose (mg/kg-day);
E	= exposure (mg/day);
AF	= absorption factor (dermal and/or inhalation); and
BW	= body weight (kg).

Handler exposure for applications to aquatic sites is generally considered short-term in duration.  Refinement of this dose estimate to reflect a more accurate short-term multi-day exposure profile can be accomplished by accounting for the various factors outlined in Section 5.0.,such as the product-specific application regimen.

Dermal and Inhalation Handler Exposure Algorithm Inputs and Assumptions
Recommended values for handler exposure (inhalation and dermal) assessments are provided in Table 6.1.  Following these tables, each scenario-specific input parameter is described in more detail.  This description includes a summary of i) key assumptions, ii) data sources used to derive recommended input values, and iii) discussion of limitations that should be addressed when characterizing exposure.

Aquatic Sites  -  Recommended Unit Exposure (mg/lb ai) Point Estimates.
                                  Formulation
                         Equipment/Application Method
                                    Dermal
                                  Inhalation
                            Appendix Page Reference


                                Point Estimate
                                Point Estimate

Granules
Spoon
                                      6.2
                                     0.087
                                       

Cup
                                     0.11
                                     0.013
                                       

Hand dispersal
                                      160
                                     0.38
                                       

Shaker can
No exposure data available for this application scenario.  Exposure data for granule applications using a cup recommended as surrogate data.
Liquid concentrates
Manually-pressurized handwand
                                      63
                                     0.018
                                       

Hose-end sprayer
                                      58
                                    0.0014
                                       

Backpack
                                      130
                                     0.14
                                       

Sprinkler can
No exposure data available for this application scenario.  Exposure data for hose-end sprayer applications of liquid concentrates recommended as surrogate data.
Wettable Powder 
Manually-pressurized handwand
                                      69
                                      1.1
                                       

Hose-end sprayer
No exposure data available for this application scenario.  Exposure data for hose-end sprayer applications of liquid concentrates recommended as surrogate data.

Backpack
No exposure data available for this application scenario.  Exposure data for manually-pressurized handwand applications of wettable powders recommended as surrogate data.

Sprinkler can
No exposure data available for this application scenario.  Exposure data for hose-end sprayer applications of liquid concentrates recommended as surrogate data.
Wettable Powder in Water-soluble Packaging
Manually-pressurized handwand
No exposure data available for this scenario.  Exposure data for manually-pressurized handwand applications of liquid concentrates recommended as surrogate data.

Hose-end sprayer
No exposure data available for this scenario.  Exposure data for RTU hose-end sprayers recommended as surrogate data.

Backpack
No exposure data available for this scenario.  Exposure data for manually-pressurized handwand applications of liquid concentrates recommended as surrogate data.

Sprinkler can
No exposure data available for this scenario.  Exposure data for RTU hose-end sprayers recommended as surrogate data.
Dry Flowable / Water-dispersible Granule
Manually-pressurized handwand
No exposure data available for this scenario.  Application method-specific exposure data for wettable powders recommended as surrogate data.

Hose-end sprayer


Backpack


Sprinkler can

Dusts/Powders
Plunger duster
                                      250
                                      1.7
                                     C-32

Bulb duster
No exposure data available for this application scenario. 
Exposure data for plunger duster applications recommended 
as surrogate data.

Electric/power duster
No exposure data available for this application scenario. 
Exposure data for shaker can applications of dusts/powders 
recommended as surrogate data.

Hand crank duster
No exposure data available for this application scenario. 
Exposure data for shaker can applications of dusts/powders 
recommended as surrogate data.

Shaker can
                                     4300
                                      18
                                     C-36
Ready-to-Use (RTU)
Hose-end sprayer
                                     6.26
                                     0.034
                                     C-107
Micro-encapsulates
Manually-pressurized handwand
No exposure data available for this scenario.  Application method-specific exposure data for liquid concentrates recommended as surrogate data.

Hose-end sprayer


Backpack


Sprinkler can


Aquatic Sites  -  Recommended Residential Handler Exposure Factor Point Estimates.
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
Application Rate (mass ai per unit area or volume)
                             Maximum labeled rate
Area treated
Ornamental backyard pond
                                500 square feet

Recreational/fish pond
                                   10 acres
Depth of water body (ft)
Ornamental backyard pond
                                       2

Recreational/fish pond
                                       7
Body Weight (kg)
                                      80

Unit Exposures
The unit exposure is the ratio, for a given formulation/application method combination, between exposure and the amount of active ingredient handled, with units mass exposure per mass active ingredient handled (e.g., mg ai exposure/lb ai handled). 

Amount of active ingredient Handled
The algorithm for estimating handler exposure requires some estimate of the amount of active ingredient handled per day. This factor varies based on the type of equipment or application method used and is estimated based on the application rate specified on the product label. First, the assessor should assemble application rate information in terms of active ingredient per area or volume treated (e.g., lb ai/acre, lb ai/1000 ft[2], lb ai/A-ft, lb ai/ft[3]).   Data on the amount of active ingredient handled are limited and difficult to collect. The amounts of active ingredient handled presented in this SOP are reasonable high-end assumptions for typical residential aquatic applications.  

For residential homeowner applications to backyard or recreational ponds, information on the amount of product used or the area treated is largely unavailable.  Therefore, a general internet search was conducted and several assumptions have been made for this input factor.  Depending on the use sites noted on the label, the following are recommendations for area treated for residential aquatic use sites:
 500 square feet surface area and a 2 foot depth for ornamental backyard ponds, and
 10 acres surface area and 7 feet depth for recreational and fish ponds.

It should be noted that the depth of the water body is only necessary in the exposure equation if the application rate is given per volume (i.e., lb ai/ft[3] or lb ai/A-ft).  

Future Research/Data Needs
Unavailable information that would refine handler exposure assessments for pesticide applications to aquatic areas include:

 Application intervals (i.e., how often chemicals are applied to aquatic sites)  -  either chemical-specific or generic information.
 Survey information (preferably longitudinal) detailing:
 Daily/weekly/monthly probability of treating aquatic sites with pesticides;
 Amount of product or formulation used or area treated per application; 
 Product-specific application rates to obtain the likelihood that the maximum rate is used.
 Handler exposure data, specifically for aquatic site applications, and/or describing the extent to which an individual's exposure for a given formulation and application method varies from application-to-application.

Exposure Characterization and Data Quality

Unit Exposures
 The exposure data underlying unit exposures are considered reasonable for the purposes of estimating exposure.  The data are from actual applications using standardized exposure sampling methodologies and laboratory analyses.
 The underlying assumption of the use of exposure data as unit exposures  -  proportionality between the amount of active ingredient handled and exposure  -  is uncertain, though potentially conservative.  However, as a prediction mechanism, it is considered practical and useful for the purposes of handler exposure assessment in a regulatory context.  It provides a straightforward handler exposure calculation method and enables risk mitigation in the form of formulation comparison and decreased application rates.
 The extent to which an individual's exposure (expressed via unit exposures) varies day-to-day or application-to-application is unknown; therefore, the assumption that there is no variation when assessing longer-term exposure durations is considered conservative.

Amount of active ingredient handled
 Information on the amounts of active ingredient handled for residential aquatic site application equipment is largely unavailable.  The estimates used, however, are believed to result in health protective exposure estimates.
 The extent to which the amount an individual will handle per application varies from day-to-day or application-to-application is unknown; therefore, the assumption that there is no variation when assessing longer-term exposure durations is considered conservative.

6.0	Post-application Exposure Assessment

Post-application exposure can result from conducting activities in previously treated areas, such as swimming in lakes and ponds following pesticide applications by professional pesticide applicators or by homeowners themselves.  It is assumed that post-application exposure will occur as a result of swimming in larger aquatic areas that may be treated by commercial applicators and/or homeowners in areas such as lakes and recreational ponds.  It is not anticipated that post-application exposure would occur after homeowner applications to smaller aquatic areas such as ornamental backyard ponds or fountains.  Adults and children 3 < 6 years old are considered the index lifestages for this exposure scenario as it is assumed that younger children (i.e., < 3 years old) won't spend as much time swimming in lakes/ponds.  Older children (6 to <11 years old and 11 to <16 years old) may spend slightly more time swimming on average, but the differences in other inputs (e.g., body weight, body surface area, inhalation rates) offset the higher exposure time input.  The exposures estimated for children 3 to <6 years old are anticipated to be protective of older children engaging in similar activities.  

The equations and inputs for estimating exposures from recreational swimming in treated aquatic areas are generally derived from the SWIMODEL, developed by EPA as a screening tool to conduct exposure assessments of pesticides found in swimming pools and spas, and EPA's Risk Assessment Guidance for Superfund  -  Part E, Supplemental Guidance for Dermal Risk Assessment ("RAGS-E").  However, some of the inputs and parameters have been updated to reflect use in bodies of water (e.g., lakes, ponds) as opposed to swimming pools.  

This section addresses standard methods for estimating exposure and dose for three scenarios resulting from swimming in treated aquatic areas such as lakes and ponds: 

 Section 5.2.1 - Inhalation exposure during recreational swimming (both adults and children 3 < 6 years old),
 Section 5.2.1 - Dermal exposure during recreational swimming (both adults and children 3 < 6 years old); and
 Section 5.2.1 - Ingestion of water during recreational swimming (both adults and children 3 < 6 years old).

It should be noted that there may be additional routes of exposure from swimming in treated waters, such as buccal/sublingual (absorbed through the mouth), orbital/nasal (absorbed through the eyes or nose), and aural (absorbed through the ear).  It is generally assumed that exposure through these routes will be less than exposure via the dermal, inhalation and oral routes.  Therefore, these additional routes are not recommended to be routinely assessed for recreational swimmers.

6.1	Post-application Inhalation Exposure Assessment

Post-application inhalation exposure during recreational swimming is dependent on three factors:  the volatility of the chemical, inhalation rate, and exposure time.  Considering the strengths and limitations of available data and behavioral characteristics of potentially exposed lifestages, post-application inhalation exposure is assessed for adults and children 3 < 6 years old.  

Post-application Inhalation Exposure Algorithm
The algorithm to calculate daily exposure and dose is shown below.  Residential post-application exposure assessment must include calculation of exposure on the day of application.  Therefore, though an assessment can present exposures for any day "t" following the application, it must include "day 0" exposure.
E=  Vp* IR * ET
Where:

E	= exposure (mg/day);
Vp	= chemical-specific vapor concentration (mg/m3),
IR	= inhalation rate (m3/hr), and
ET	= exposure time (hrs/day).
 Vp= Cw* H,*1,000 Lm3

Where:

Vp	= chemical-specific vapor concentration (mg/m3),
Cw	= chemical concentration in water (mg/L), and
H'	= dimensionless Henry's Law constant (unitless).
      	
H'= HLCR*T
Where:

H'	= dimensionless Henry's Law constant (unitless),
HLC	= Henry's law constant (atm-m[3]/mole),
R 	= gas constant (8.19E-5 atm-m[3]/mole-K), and 
T	= ambient temperature in terms of Kelvin units (293K = 20[o]C).

Absorbed inhalation dose, normalized to body weight, is calculated as:

      D= E*AFBW
		
Where:

D	= dose (mg/kg-day);
E	= exposure (mg/day);
AF	= absorption factor (inhalation); and
BW	= body weight (kg).

Post-application inhalation exposure following recreational swimming in treated aquatic areas is generally considered short-term in duration.  Refinement of this dose estimate to reflect a more accurate short-term multi-day exposure profile can be accomplished by accounting for the various factors outlined in Section 5.0 (all) such as residue dissipation, product-specific re-treatment intervals, and activity patterns.  If longer-term assessments (i.e., intermediate-, long-term, or lifetime exposures) are deemed necessary, similar refinements to more accurately reflect the exposure profile are recommended.


Post-application Inhalation Exposure Algorithm Inputs and Assumptions
Recommended values for post-application inhalation exposure assessments are provided in 6.1.1 below.  Following this table, each scenario-specific input parameter is described in more detail.  This description includes a summary of i) key assumptions; ii) data sources used to derive recommended input values; and iii) discussion of limitations that should be addressed when characterizing exposure.  

Aquatic Applications  -  Recommended Point Estimates for Post-Application Inhalation Exposure Factors.
                              Algorithm Notation
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
                                      Vp
Chemical-specific vapor concentration (mg/m[3])
Calculated based on chemical concentration in water and dimensionless Henry's law constant
                                      Cw
Chemical concentration in water (mg/L)
         Based on either (1) monitoring data or (2) label information
                                     H'
Dimensionless Henry's Law constant (unitless)
                                  Calculated
                                      HLC
Henry's Law constant (atm-m[3]/mole)
                               Chemical-specific
                                       R
Gas constant (atm-m[3]/mole-K)
                                   8.19E-5 
                                       T
Ambient temperature in terms of Kelvin units (K)
                                      293
                                      IR
Inhalation rate (m[3]/hr)
Adult
                                     0.64
                                       

Children 3 to <6 years old
                                     0.42
                                      ET
Exposure Time (hrs per day)
Adult
                                     0.025
                                       

Children 3 to <6 years old
                                     0.076
                                      BW
Body weight (kg)
Adults
                                      80


Children 3 < 6 years old
                                      19

Chemical concentration in water (Cw) 
The chemical concentration in water can be estimated based on (1) chemical-specific monitoring data or (2) the application rate provided on the product label.  If the application rate provided on the label is only given in lb active ingredient (ai) per area (rather than lb ai/volume), then an assumption of 4 feet depth (and uniform distribution) can be used to estimate the concentration in water.  The assumption of 4 feet depth is based on best professional judgement, and is not meant to correspond to the assumption of water depth used for the residential handler assessment (if used), since the post-application assessment is meant to represent exposure to large water bodies treated by professional applicators that would typically be used for swimming (e.g., lakes, ponds, etc) and not smaller water bodies assumed to be treated by homeowners (e.g., backyard ponds or fountains).  It is acknowledged that lakes and ponds may have depths greater than 4 feet, but by using the assumption of 4 feet and uniform distribution, the calculation of water concentration results in a more conservative estimate.    

Inhalation Rate (IR)
See Section 2.2 for discussion of inhalation rates.  The recommended point estimates for use 
in post-application inhalation exposure assessments are 0.64 m[3]/hr for adults and 0.42 m[3]/hr for children 3 < 6 years old.


Henry's Law Constant (HLC)
A chemical-specific value in units of atm-m[3]/mole.

Gas constant (R)
A constant value of 8.19 x 10[-5] atm-m[3]/mole-K.

Ambient temperature in units of Kelvin (T)
A constant value of 293 K.

Exposure Time (ET)
The exposure time for swimming in aquatic areas is based on information provided in the 2011 Exposure Factors Handbook (USEPA, 2011).  Data are provided on the number of minutes per month spent swimming in a freshwater swimming pool (Tables 16-40 and 16-42).  Using these data, monthly time-weighted averages were calculated and the recommended point estimates for use in post-application inhalation exposure assessments are 0.025 hour/day for adults and 0.076 hour/day for children 3 < 6 years old.  

Future Research/Data Needs
Unavailable information that would refine post-application inhalation exposure assessments for pesticide applications to aquatic areas include:

 Application intervals (i.e., how often chemicals are applied to aquatic areas)  -  either chemical-specific or generic information.
 Survey information (preferably longitudinal) detailing:
 Daily/weekly/monthly probability of treating aquatic areas with pesticides;
 Product-specific application rates to obtain the likelihood that the maximum rate is used; and,
 Daily activity patterns specific to aquatic areas.
 Post-application exposure data, specifically for aquatic areas, and/or describing the extent to which an individual's exposure for a given activity varies.  


Exposure Characterization and Data Quality
 The vapor concentration of the pesticide applied to aquatic areas is expected to be a highly conservative estimate since the applications are made outdoors and it is expected that the concentration of the chemical will be diluted in outdoor air.
 The equations used to estimate inhalation exposure are more appropriate for chemicals that are considered volatile and may overestimate concentration for certain pesticides.
 The exposure time for swimming in aquatic areas is based on the average time spent in a freshwater swimming pool and is used as a surrogate for swimming in lakes/ponds.

6.2	Post-application Dermal Exposure Assessment

Post-application dermal exposure resulting from recreational swimming in previously treated aquatic areas are based on the chemical properties of the active ingredient and exposure factors such as surface area and exposure time.  Considering the strengths and limitations of available data and behavioral characteristics of potentially exposed lifestages, post-application dermal exposure is assessed for adults and children 3 < 6 years old.  

Post-application Dermal Exposure Algorithm
The algorithm to calculate daily exposure and dose is shown below. Residential post-application exposure assessment must include calculation of exposure on the day of application.  Therefore, though an assessment can present exposures for any day "t" following the application, it must include "day 0" exposure.

E= Cw* Kp*SA*ET*CF
Where:

E	= exposure (mg/day),
Cw	= chemical concentration in water (mg/L),
Kp	= permeability constant (see equation below),
SA	= surface area (cm2),
ET	= exposure time (hrs/day),
CF	= conversion factor (0.001 L/cm3)

Kp= 10-2.72+ 0.71*logKow- 0.0061*MW
Where:

Kp	= permeability constant (cm/hr),
Kow	= octanol water coefficient,
MW	= molecular weight (g/mol).		


Absorbed dermal dose, normalized to body weight, is calculated as:
D= EBW
Where:

D	= dose (mg/kg-day);
E	= exposure (mg/day); and
BW	= body weight (kg).

Post-application dermal exposure following applications to aquatic areas is generally considered short-term in duration.  Refinement of this dose estimate to reflect a more accurate short-term multi-day exposure profile can be accomplished by accounting for the various factors outlined in Sections 5.0 (all) such as residue dissipation, product-specific re-treatment intervals, and activity patterns.  If longer-term assessments (i.e., intermediate-, long-term, or lifetime exposures) are deemed necessary, similar refinements to more accurately reflect the exposure profile are recommended.



Post-application Dermal Exposure Algorithm Inputs and Assumptions
Recommended values for post-application dermal exposure assessments are provided in Table below.  Following this table, each scenario-specific input parameter is described in more detail.  This description includes a summary of i) key assumptions; ii) data sources used to derive recommended input values; and iii) discussion of limitations that should be addressed when characterizing exposure.  

Aquatic Applications  -  Recommended Point Estimates for Post-Application Dermal Exposure Factors.
                              Algorithm Notation
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
                                      Cw
Chemical concentration in water (mg/L)
         Based on either (1) monitoring data or (2) label information
                                      Kp
Permeability constant
                        Chemical-specific or calculated
                                      SA
Surface area (cm[2])
Adults
                                    19,500
                                       

Children 3 < 6 years old
                                     7,600
                                      ET
Exposure Time (hrs per day)
Adults
                                     0.025
                                       

Children 3 < 6 years old
                                     0.076
                                      BW
Body weight (kg)
Adults
                                      80


Children 3 < 6 years old
                                      19

Chemical concentration in water (Cw) 
The chemical concentration is water can be estimated based on (1) chemical-specific monitoring data or (2) the application rate provided on the product label.  If the application rate provided on the label is only given in lb active ingredient (ai) per area (rather than lb ai/volume), then an assumption of 4 feet depth (and uniform distribution) can be used to estimate the concentration in water.  The assumption of 4 feet depth is based on best professional judgement, and is not meant to correspond to the assumption of water depth used for the residential handler assessment (if used), since the post-application assessment is meant to represent exposure to large water bodies treated by professional applicators that would typically be used for swimming (e.g., lakes, ponds, etc) and not smaller water bodies assumed to be treated by homeowners (e.g., backyard ponds or fountains).  It is acknowledged that lakes and ponds may have depths greater than 4 feet, but by using the assumption of 4 feet and uniform distribution, the calculation of water concentration results in a more conservative estimate.  

Permeability constant (Kp)
The permeability constant (cm/hr) is chemical-specific and can be estimated based on an equation for organic chemicals provided by EPA's Dermal Exposure Assessment: Principles and Applications (U.S. EPA, 1992).  NOTE:  Since the permeability constant provides estimates of an internal dose from the dermal route of exposure, the oral toxicity endpoint rather than the dermal toxicity endpoint is used to assess the risks from the dermal swimming route.

Surface area (SA)
The body surface area exposed during recreational swimming is based on the 2011 Exposure Factors Handbook (USEPA, 2011) Tables 7-9 to 7-11.  These estimates of body surface area represent total body surface area, and are considered conservative considering adults and children are assumed to be wearing bathing suits while swimming.  The recommended point estimates for use in post-application dermal exposure assessments are 19,500 cm[2] for adults and 7,600 cm[2]for children 3 < 6 years old.

Exposure Time
The exposure time for swimming in aquatic areas is based on information provided in the 2011 Exposure Factors Handbook (USEPA, 2011).  Data are provided on the number of minutes per month spent swimming in a freshwater swimming pool (Tables 16-40 and 16-42).  Using these data, monthly time-weighted averages were calculated and the recommended point estimates for use in post-application inhalation exposure assessments are 0.025 hour/day for adults and 0.076 hour/day for children 3 < 6 years old. 

Future Research/Data Needs
Unavailable information that would refine post-application dermal exposure assessments for pesticide applications to aquatic areas include:
 Application intervals (i.e., how often chemicals are applied to aquatic areas)  -  either chemical-specific or generic information.
 Survey information (preferably longitudinal) detailing:
 Daily/weekly/monthly probability of treating aquatic areas with pesticides;
 Product-specific application rates to obtain the likelihood that the maximum rate is used; and,
 Daily activity patterns specific to aquatic areas.
 Post-application exposure data, specifically for residential aquatic area activities, and/or describing the extent to which an individual's exposure for a given activity varies.

Exposure Characterization and Data Quality
 Dermal permeability values are estimated based on an equation recommended in the EPA Dermal Exposure Assessment: Principles and Applications (EPA, 1992), which provides non-steady state values based on the molecular weight and the log Kow partitioning coefficient (i.e., lipophilicity).
 The exposure time for swimming in aquatic areas is based on the average time spent in a freshwater swimming pool and is used as a surrogate for lakes/ponds.


6.3	Post-application Non-Dietary Ingestion Exposure Assessment

This SOP provides a standard method for estimating the dose for adults and children 3 < 6 years old from incidental ingestion of water from treated aquatic areas (e.g., lakes).   This scenario assumes that swimmers ingest water that enters their mouth during swimming or playing in the treated water.  

Post-application Incidental Ingestion Exposure Algorithm
Exposure from incidental ingestion of treated water is calculated as follows:

E= Cw*IgR*ET
Where:

E	= exposure (mg/day),
Cw	= chemical concentration in water (mg/L),
IgR	= ingestion rate of water (L/hr),
ET 	= exposure time (hrs/day).

Dose, normalized to body weight, is calculated as:

D= EBW
Where:

D	= dose (mg/kg-day);
E	= exposure (mg/day);
BW	= body weight (kg).

Post-application incidental ingestion following aquatic applications is generally considered short-term in duration. Refinement of this dose estimate to reflect a more accurate short-term multi-day exposure profile can be accomplished by accounting for the various factors outlined in Sections 1.3.2 and 1.3.4, such as residue dissipation, product-specific re-treatment intervals, and activity patterns. If longer-term assessments (i.e., intermediate-, long-term, or lifetime exposures) are deemed necessary, similar refinements to more accurately reflect the exposure profile are recommended. 

Post-application Incidental Ingestion Exposure Algorithm Inputs and Assumptions
Recommended values for post-application incidental ingestion exposure assessments are provided in Error! Reference source not found. below.  Following this table, each scenario-specific input parameter is described in more detail.  This description includes a summary of i) key assumptions; ii) data sources used to derive recommended input values; and iii) discussion of limitations that should be addressed when characterizing exposure.  

Aquatic Applications  -  Recommended Point Estimates for Post-Application Incidental Ingestion Exposure Factors.
                              Algorithm Notation
                                Exposure Factor
                                    (units)
                               Point Estimate(s)
                                      Cw
Chemical concentration in water (mg/L)
         Based on either (1) monitoring data or (2) label information
                                      IgR
Ingestion rate (L/hr)
                                     0.05
                                      ET
Exposure Time
(hours per day)
Adults
                                     0.025
                                       

Children 3 < 6 years old
                                     0.076
                                      BW
Body weight
(kg)
Adults
                                      80


Children 3 < 6 years old
                                      19

Chemical concentration in water (Cw) 
The chemical concentration is water can be estimated based on (1) chemical-specific monitoring data or (2) the application rate provided on the product label.  If the application rate provided on the label is only given in lb active ingredient (ai) per area (rather than lb ai/volume), then an assumption of 4 feet depth (and uniform distribution) can be used to estimate the concentration in water.  

Ingestion rate of water (IgR)
Water ingestion rates are based on the Risk Assessment Guidance for Superfund (RAGS) Part A (http://www.epa.gov/oswer/riskassessment/ragsa/) which references a value from the Superfund Exposure Assessment Manual (USEPA, 1988).  The recommended point estimate for use in post-application incidental ingestion exposure assessments is 0.05 L/hr of swimming for adults and children 3 < 6 years old.

Exposure Time
The exposure time for swimming in aquatic areas is based on information provided in the 2011 Exposure Factors Handbook (USEPA, 2011).  Data are provided on the number of minutes per month spent swimming in a freshwater swimming pool (Tables 16-40 and 16-42).  Using these data, monthly time-weighted averages were calculated and the recommended point estimates for use in post-application inhalation exposure assessments are 0.025 hour/day for adults and 0.076 hour/day for children 3 < 6 years old.  

Future Research/Data Needs
Unavailable information that would refine post-application ingestion exposure assessments for pesticide applications to aquatic areas include:

 Application intervals (i.e., how often chemicals are applied to aquatic areas)  -  either chemical-specific or generic information.
 Survey information (preferably longitudinal) detailing:
 Daily/weekly/monthly probability of treating aquatic areas with pesticides;
 Product-specific application rates to obtain the likelihood that the maximum rate is used; and,
 Daily activity patterns specific to aquatic areas.
 Post-application exposure data, specifically for residential aquatic area activities, and/or describing the extent to which an individual's exposure for a given activity varies.

Exposure Characterization and Data Quality
 The study on which the water ingestion rates are based is a pilot study which attempted to measure water ingested while swimming.  While it is one of the first attempts at collecting this type of information, the study has some limitations.  One limitation is that the number of participants is low.  The study population included 12 adults (4 males and 8 females) and 41 children under 18 years of age (20 males and 21 females).  Another limitation is that the swimmers were studied while swimming in pool water, and the study author noted that the swimming behavior of pool swimmers may be similar to freshwater swimmers, but may differ from salt water swimmers.
 The exposure time for swimming is based on the average time spent in a freshwater swimming pool, and is used as a surrogate for lakes/ponds. 



Appendix B.  Summary of Label Directions concerning Aquatic Uses

Aquatic use directions for Diquat Dibromide 
Total application volume per area  not to exceed equivalent of 40 lb/SA per year for all treatments		
Volume required to not exceed 4 lbs ai per surface acre (SA) based upon spray solution concentration	
Wait 14 days between treatments									
Do not use for drinking for a period of 3 days if applied at 4 lb ai1/SA, 2 days if applied at 2  to 1.5 lb ai1/SA, 1 day if applied at 1 lb ai1/SA,  or  1 day for spot spray (< 1 lb ai1/SA) applications.  			
0 day water use restriction for fishing and swimming 							
 Do not allow livestock or domestic animals to consume treated water for 1 day following application	
Do not use treated water for spray tank applications and irrigation to turf and landscape ornamentals for 3 days if applied at 4 lb ai1/SA, 2 days if applied at 2 lb ai1 or 1.5 lb ai1/SA, 1 day if applied at 1 lb ai1 /SA or 1 day for spot spray (< 1 lb ai1/SA) applications.  								
 Do not use treated water for spray tank applications and irrigation to food crops and production  ornamentals until 5 days after application									
 Water use restrictions restriction codes 5 -9) do not apply if treated water is demonstrated to not contain more than the designated maximum contaminant level goal (MCLG) of 0.02 mg/l (ppm) of diquat dibromide (calculated as cation) 	
No applications are to be made in areas where commercial processing of fish, resulting in the production of fish protein concentrate or fish meal is practiced. To control submersed weeds, apply at rate of 1 - 4 lb ai1/SA (per 4 foot depth). 		
For application only to still waters (i.e. ponds, lakes, and drainage ditches) where there is minimal or no outflow to public water
Public Waters (ponds, lakes, reservoirs, marshes, bayous, drainage ditches, canals, streams, rivers, and other slow-moving or quiescent bodies of water). If applied to public waters, must be used by Corps or Engineers, or Federal/State Public Agencies, or Applicators (and/or Licensees) certified for aquatic pest control that are authorized by state or local government.		
Do not apply within 1600 feet upstream or within 400 feet down steam of operating potable water intake sites. Do not apply within 1400, 700, or 350 feet of potable water intake for rates of 4, 2, or 1 lb ai1/SA respectively.
Do not use the treated water for animal consumption, spraying, irrigation, or domestic purposes for 14 days after treatment
For 24C registrations; Do not treat water where depth is 3 feet or less. Do not apply by air.		
Do not combine with copper.									
Do not use for Algae control. Do not use for water lettuce.					
Do not apply under conditions involving possible drift to food, forage or other plantings that might be damaged or the crops thereof rendered unfit for sale, use or consumption.					
For water depths of 2 feet or less including shorelines, do not exceed 1 gallon per surface acre.		
Apply only by spray to surface of lake with boom sprayer						
Not for sale or use in New York State without supplemental special local needs labeling			
To make application within these restricted areas, the intake must turned off for the time period specified on the Federal label or until the treated area contains less than the designated maximum contaminant level (MCL) of 0.02 mg/L (ppm) of diquat dibromide calculated as the cation by an approved assay [example: PAM II Spectrometric Method]		
Prior to using this product in a particular county, contact the local Extension Service Office or the U.S. Fish and Wildlife Service for procedures and precautions to protect the threatened or endangered species.		







References

Pond Kits, Koi-Garden Pond Kits-Waterfall Kits. 2013. 
(http://www.pondandgardenwholesalers.com/servlet/the-Pond-Kits--dsh-by-size/Categories).

Ornamental and Retention Ponds:  Bridging the Gap Between Functional and Beautiful.  2004.
(http://www.landandwater.com/features/vol49no2/vol49no2_1.html).

A Pond in Your Garden.  Garden World.  2011.
(http://www.gardenworld.co.uk/a-pond-in-your-garden/).

GreenShare Factsheets.  University of Rhode Island Landscape Horticulture Program.  Water Gardens.  2001.
(http://www.uri.edu/ce/factsheets/sheets/watergarden.html).

Backyard Conservation  -  Backyard Ponds.  United States Department of Agriculture, Natural Resources Conservation Service.  
(http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/newsroom/features/?cid=nrcs143_023601).

Build Your Own Pond.  Popular Mechanics.  2006.
(http://www.popularmechanics.com/home/improvement/outdoor-projects/2770526).

Management of Recreational and Farm Ponds in Louisiana.  Louisiana State University Agricultural Center.  2003.
(http://www.wlf.louisiana.gov/sites/default/files/pdf/publication/32846-management-recreational-and-farm-ponds-louisiana/mgmt-of-farm-ponds.pdf).

Texas Farm Ponds:  Stocking, Assessment, and Management Recommendations.  Texas Agricultural Extension Service.  1996.
(http://theurbanrancher.tamu.edu/retiredsite/aquatic/farmpond.pdf).

Guidelines for Designing and Managing Florida Ponds for Recreation.  Florida Fish and Wildlife Conservation Commission.  
(http://www.myfwc.com/conservation/you-conserve/recreation/pond-management/).

Pond Management: Construction.  Virginia Department of Game and Inland Fisheries.  2013.
(http://www.dgif.virginia.gov/fishing/pondmanagement/construction.asp).

U.S. Army Corp. of Engineers  -  Kurt Getsinger (Aquatic use)

U.S. EPA. (1988). Superfund Exposure Assessment Manual. U.S. Environmental Protection Agency, Washington, DC.  EPA/540/1-881001.

