UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460      

	OFFICE OF CHEMICAL SAFETY

 AND POLLUTION PREVENTION

	

  SEQ CHAPTER \h \r 1 MEMORANDUM	(DRAFT)

Date:	March 24, 2015

SUBJECT:	Review of “Determination of Dermal and Inhalation Exposure to
Workers during Backpack and Handgun Application of Liquid Sprays in
Utilities Rights-of-Way” (AHE400)

 

PC Code:  --	DP Barcode:  D424153

Decision No.: --	Registration No.: --

Petition No.: --	Regulatory Action: -- 

Risk Assessment Type:  -- 	Case No.: --

TXR No.: --	CAS No.: --

MRID No.: 49472001	40 CFR: --

		              									

	          	

FROM:	Matthew Crowley, Biologist

		Chemistry and Exposure Branch

Health Effects Division  SEQ CHAPTER \h \r 1 		

THROUGH:	David J. Miller, Chief

		Chemistry and Exposure Branch

		Health Effects Division

TO:		Richard Dumas		  SEQ CHAPTER \h \r 1   SEQ CHAPTER \h \r 1 

		Pesticide Registration Division			  SEQ CHAPTER \h \r 1   SEQ CHAPTER
\h \r 1 

	

This memorandum presents EPA’s review of the analytical and field
phase reports for AHE400 (AHETF, 2014), an Agricultural Handler Exposure
Task Force (AHETF) study monitoring dermal and inhalation exposure for
workers making backpack or handgun applications of liquid sprays to
utility rights-of-way and similar areas.  The scenario monographs
(Bruce, et al, 2014a and 2014b), which incorporate the monitoring data
from AHE400 into single/composite datasets and includes statistical
analysis based on pre-defined benchmark accuracy objectives, are
reviewed under separate cover (Crowley, 2015a and 2015b).

This study meets EPA standards for occupational pesticide exposure
monitoring and are considered acceptable and appropriate for use in
occupational exposure assessments for backpack and handgun applicators.

1.0	Executive Summary

The Agricultural Handler Exposure Task Force (AHETF) monitored dermal
and inhalation exposure for 21 workers using handgun sprayers and 19
workers using backpack sprayers while applying liquid spray pesticides
to undesirable vegetation such as shrubs, vines, and trees in areas such
as utility rights-of-way (ROW), parks, roadsides, and wildlife refuges
across the eastern half of the United States.  Importantly, the
pesticide solution was not prepared by the monitored workers; thus,
results of monitoring did not include exposures during the pesticide
mixing process.

Backpack applications in this study were conducted using a handwand
attached to a low-volume tank worn on a worker’s back.  While walking
through the target area, the pesticide solution is sprayed by manually
pressurizing the spray tank with a hand-pump attached to the backpack
and squeezing the trigger on the wand.  Additionally, some of the
workers using backpacks also performed “hack-and-squirt”
applications (a direct/localized spray following a slice/cut to the base
of a tree or bush).

Handgun applications in this study were conducted with a handgun
attached to a hose, which is in turn attached, through a mechanical
pump, to a vehicle-mounted holding tank.  The mechanical pump provides
the pressure to spray the pesticide solution.  The workers often sprayed
the target vegetation from the vehicles, but at times had to drag the
hose and walk in and around the targeted areas.  

Table 1 presents a high-level summary of all of the exposure monitoring.

Table 1.  AHE400 Summary

Equipment	Site	State	No. Monitored Worker-Days	Monitoring Year

(for each Worker-day)	Age Range

(years)

Backpack	ROW & Park	PA	3	2012/-12/-13	29-53



NC	1	2011	33

	ROW	GA	1	2011	29



SC	1	2012	38

	Wildlife Refuge & ROW	FL	3	2011/-12/-12	26-48

	ROW	AR	3	2011/-12/-12	21-31

	Pipeline terminal & ROW	IN	2	2012/-13	24-34

	Park & Drainage ditch	MI	2	2012/-13	33-37

	ROW	TX	3	2011/-12/-12	27-29

Handgun	ROW	PA	2	2012	54-68



WV	1	2012	49



NC	2	2011/-13	34-47



TN	1	2012	48



FL	3	2011/-13/-13	27-54



MN	2	2013/-13	20-48

	Fence line & ROW	LA	3	2012/-12/-12	20-48

	Pipeline terminal & ROW	IN	3	2012/-12/-13	19-39

	Roadsides	MI	1	2012	45

	Drainage ditch & ROW	TX	3	2011/-11/-12	25-58

Note:  all study subjects were male.



Monitored on actual days of work, backpack applicators handled from 0.03
to 9.65 lbs of active ingredient, spraying 4.5 to 64.5 gallons of
solution in 2 to 10.7 hours, covering (when recorded) less than 1 to
approximately 6 acres.  Handgun applicators handled from 0.077 to 45.95
lbs of active ingredient, spraying 71 to 2900 gallons of solution in 3.3
to 11.4 hours, covering less than 1 to approximately 20 acres. 
Applicators wore long-sleeved shirts, pants, shoes/socks and
chemical-resistant gloves, with a few donning protective leggings and
eye protection.  No applicator wore a respirator.

Dermal exposure was measured using hand washes, face/neck wipes, and
whole body dosimeters (100% cotton union suits) for the remainder of the
body (torso, arms, and legs).  Inhalation exposure was measured using
personal air sampling pumps and OSHA Versatile Samplers (OVS) mounted on
the shirt collar.

All studies followed the applicable and most up-to-date AHETF standard
operating procedures (SOPs) and their corresponding protocols with
deviations appropriately recorded.  No protocol deviation is considered
to have compromised the overall research.  Analytical field and
laboratory recovery results were acceptable, generally averaging between
70 and 120% recovery, with coefficients of variation generally lower
than 25%.  All field samples were appropriately adjusted for the
corresponding recovery adjustment factors.  

Total dermal exposure, calculated by summing the results for inner
dosimeters, hand washes and face/neck wipes, as well as dermal exposure
normalized to body weight and also normalized to the amount of active
ingredient handled are summarized in Table 2 below.

Table 2.  Dermal Exposure Summary

Equipment	Statistic1	Total Exposure

(μg)	Normalized by Body Weight

(μg/kg BW)	Normalized by Amount ai Handled

(μg/lb ai)2

Backpack	Minimum	34	0.48	675

	Maximum	752,379	8,360	241,923

	Mean	73,414	855	31,273

Handgun	Minimum	80	0.88	26

	Maximum	112,258	1,467	12,123

	Mean	12,431	135	1,868

1 Means are simple averages (i.e., sum of values ÷ n)

2 Though other exposure metrics are shown in this table, exposure
normalized to the amount of active ingredient handled is typically the
format used by EPA as an input in standard handler exposure
calculations.



Total inhalation exposure, calculated assuming a breathing rate of 16.7
L/min, as well as inhalation exposure normalized to body weight and also
normalized to amount of active ingredient handled are summarized in
Table 3 below.

Table 3.  Inhalation Exposure Summary

Equipment	Statistic	Total Exposure

(μg)	Normalized by Body Weight

(μg/kg BW)	Normalized by Amount ai Handled

(μg/lb ai)

Backpack	Minimum	0.54	0.007	1.74

	Maximum	567	7	112

	Mean	100	1.22	35

Handgun	Minimum	0.24	0.003	0.18

	Maximum	670	8.28	35

	Mean	88	1.09	7

Note:  Means are simple averages (i.e., sum of values ÷ n)



Summary of Field Study Characteristics

This section provides summary characteristics for AHE400.  While a
summary is provided, the submitted AHE400 report should be consulted for
more specific details (applicable sections, tables, and/or page numbers
are provided).

 

Administrative Summary

AHE400 was sponsored by the AHETF and adequately followed both the
protocol and scenario construction plan (AHETF, 2010a), the AHETF
Governing Document (AHETF, 2008 and 2010b), and applicable AHETF SOPs.  

The study was conducted in compliance with Good Laboratory Practice
Standards (GLPS) (40 CFR §160) and met the standards in EPA Test
Guidelines Series 875 – Occupational and Residential Exposure
(875.1100 – dermal exposure; 875.1300 – inhalation exposure). 
Deviations from GLPS are noted in AHE400 pages 3-4 – none are
considered to have substantially impacted the study conduct or results. 
Signed copies of acceptable Quality Assurance and Data Confidentiality
statements were provided.

Protocol amendments included:  adding additional sources for
recruitment; allowance for additional clothing such as rubber boots,
leggings, and headgear; allowance for sites that are not strictly
rights-of-way but are similar in terms of vegetation and terrain and
would be subject to similar pesticide applications; increases to field
fortification levels; analytical method specifications; and relaxing the
“different employer” requirement.  The amendments are all considered
reasonable accommodations in order to carry out the study and were
appropriately documented.  

Protocol deviations included:  use of analytical methods that were
validated but had yet to be specified in the protocol; failure to meet
monitoring time and load thresholds; potential lack of sampling test
substance lots; failure to perform a hand wash at a break; use of
non-AHETF provided gloves; failure to notify potential employers of an
introductory letter and phone call; air sampling pump issues; and a
change to a principal analytical investigator.  None are considered to
have negatively impacted the study conduct or results.

For a more detailed summary of amendments and deviations, see Section
4.0 below and refer to AHE400 pages 11-14 as well as Appendix A (pages
454-538).

Test Materials

Four potential surrogate active ingredients, all herbicides, were
specified in the protocol:  glyphosate, fosamine, 2,4-D, and imazapyr. 
Backpack applications utilized 3 of 4 of the surrogates, each one
spraying either glyphosate, fosamine, or imazapyr.  Handgun applications
utilized all four surrogate herbicides, each one spraying either
glyphosate, fosamine, 2,4-D, and imazapyr.

Per GLP, AHETF analyzed the test substances for purity.  Certificates of
Analysis, which formally document analysis of the test substances, are
provided in AHE400 Appendix F pages 1400-1430.  AHETF determined that
analysis of “Pre-Mix” products were suspect due to homogeneity
concerns and would instead, where applicable, use the label-specified
active ingredient concentrations to calculate amount of active
ingredient handled.  Additionally, in some cases a sample of the product
used was unattainable for analysis, so the nominal concentration listed
by the manufacturer on the product was used.

AHE400 pages 65-68 and Table B-2 on pages 92-93 provides more specific
details on the products used and methodologies for calculating amount of
active ingredient handled.  This is also described more in Section 2.7
below.

Sample Size, Monitored Workers, and Locations

According to the Backpack and Handgun ROW Scenario Construction Plan
(AHETF, 2010a) and the AHETF Governing Document (AHETF, 2008 and 2010b),
a “7 x 3” configuration was deemed a reasonable approach for these
scenarios.  That is, for each of the two scenarios, a total of 21
“monitoring units” (MU), obtained by monitoring exposure from 7
spatially distinct study locations across the eastern U.S., each with 3
workers per location would be likely to satisfy pre-defined accuracy
benchmarks.

Ultimately, 21 separate workers were monitored conducting handgun
applications and 19 were monitored conducting backpack applications. 
The AHETF decided to terminate the backpack monitoring due to logistical
difficulties and because they believed the resulting dataset would be
adequate to meet scenario benchmarks.  Discussion of the sampling design
and related issues is covered under a separate review (Crowley, 2015a
and 2015b).

Monitoring locations were all places where undesirable vegetation such
as shrubs, vines, or bushes were meant to be controlled.  Most of the
monitoring was in utility rights-of-ways, such as areas through which
electric transmission and distribution lines or pipelines run.  These
are areas where controlling vegetation is important so as to not only
provide easy access to utility personnel and vehicles, but also because
the vegetation can damage utility distribution equipment.  Other
monitoring areas included parks, drainage ditches, wildlife refuges,
fence lines, and roadsides where these types of pesticide applications
are also conducted.  While these are not rights-of-way, both the purpose
of the application (i.e., controlling undesirable vegetation) and
location characteristics such as terrain and vegetation type were
similar to the right-of-way locations that constituted the bulk of the
monitoring.

Table 4 below provides some more detailed characteristics of the workers
and locations.  The AHE400 study report provides additional backpack
applicator details in Table BP-3 on pages 94-97 and handgun applicator
details in Table HG-3 on pages 284-287. 

Table 4.  Worker and Location Summary

Equipment	Age Range (years)	Gender	Weight (lb)	Work Experience (years)
Site/Target	State	Monitoring Years

Backpack	21 -53	All male	137 - 351	< 1 to 15	Distribution line ROW
PA/SC/NC/AR/IN	2011-2013





	Transmission line ROW	PA/GA/FL/AR/TX	2011-2013





	Wildlife refuge	FL	2011





	Pipeline ROW	IN	2012





	Park	PA/MI	2012-2013





	Drainage ditch	MI	2013

Handgun	19 – 68	All male	127 - 251	< 1 to 34	Distribution line ROW
NC/TN/LA/IN/MN/TX	2011-2013





	Transmission line ROW	PA/WV/NC/FL/LA/TX	2011-2013





	Dist. and Trans. line ROW	PA	2012





	Drainage ditch	TX	2011





	Roadsides	MI	2012





	Fence line	LA	2012





	Pipeline terminal	IN	2013



Environmental Conditions

Temperature (including heat index), humidity, wind speed and direction,
cloud cover, and rainfall were all reported.  The maximum reported
temperature was 93° F (Handgun application, TX, 2011 and Backpack
application, AR, 2012) and the lowest reported temperature was 45° F
(Handgun application, WV, 2012).  Rain impacted some of the monitoring. 
For two handgun applications, monitoring was halted during rain and the
applicators took shelter and resumed applications after the rain
stopped.  Additionally, for each a backpack and handgun application,
rain halted monitoring, but in each case in terms of time, amount
applied, etc. monitoring was sufficiently complete when halted.  Maximum
reported wind speed was approximately 20 miles per hour.

In a few instances monitoring was affected or halted because the ambient
temperature exceeded the pre-defined threshold of concern for potential
heat-related injury:  one backpack application in West Virginia in 2012
(heat index = 106° F) and two handgun applications (both in Texas, heat
indices of 105° F in 2011 and 110° F  in 2012).  However in all cases
in terms of time, amount applied, etc. monitoring was sufficiently
complete by the time the application was halted.

For more details on environmental conditions see the AHE400 report
tables BP-7 (pages 106-109) and HG-7 (pages 296-299).

Clothing and Personal Protective Equipment (PPE)

Per the stated goals of the AHETF, monitoring of backpack and handgun
applications to undesirable vegetation in rights-of-way or similar areas
was conducted to represent exposure for workers wearing long-sleeve
shirts, pants, shoes/socks, chemical-resistant gloves and no respiratory
protection.  While this was largely the case, because of the nature of
the terrain and environment nearly all workers wore (company-required)
hard hats and some wore additional leg coverings (7 backpack
applicators, 2 handgun applicators) to protect from thorns or snakes.

So long as the work clothing met the standards of the EPA Worker
Protection Standard (WPS), monitoring was conducted with the clothing
worn by the worker on the scheduled monitoring day.  In three instances,
the AHETF supplied workers with replacement shirts or pants prior to
study initiation.

Per protocol, new chemical-resistant gloves were supplied by the AHETF
to all workers at the beginning of the day and were available throughout
the day according to WPS requirements.  In one instance a worker
(backpack applicator A27) preferred to wear his own chemical-resistant
gloves – this was noted as a protocol deviation.  Additionally, many
workers, either due to company policy or worker preference or required
by the pesticide label, wore protective eyewear.  In these cases, the
exposure measurements were adjusted (according to AHETF SOP 9.K) to
extrapolate deposited residue to those portions of the face/head covered
by the protective eyewear.

More specific details on work clothing and PPE can be found in the
AHE400 study report in Tables BP-4 and BP-5 on pages 98-101 and Tables
HG-4 and HG-5 on pages 288-291.

Application Equipment and Methods

For these studies, as indicated above, only application with either a
backpack or handgun was monitored – monitoring was not conducted for
those workers responsible for mixing and loading the pesticide.  

For backpack applications, the worker used a handheld wand/hose/nozzle
apparatus attached to a 3 to 4 gallon spray tank mounted to their backs
with shoulder straps.  The spray tank solution was pressurized manually
using a lever.  The spray nozzle typically had a dual set-up where
workers could switch between a straight stream or broad/fan stream.  In
three instances, in addition to the standard backpack applications,
workers also conducted “hack-and-squirt” applications, also known as
“frill” applications.  For these, the trunk of a tree or bush is cut
with a knife or machete, and spray solution applied with a small squirt
bottle.

For handgun applications, the worker sprayed with a wand/hose/nozzle
apparatus attached to vehicle-mounted mechanical pressurizing pump and
large spray tank.  Vehicle types varied including all-terrain vehicles
(ATVs), trucks and tractors.  Workers sprayed the target vegetation from
the vehicles, but also at times got off the vehicle dragging the hose
behind them while walking through the area.  Spray pressures varied,
with most less than 100 pounds per square inch (psi), though some others
used higher-pressure rigs (e.g., 800 psi) that can spray up to 30 feet.

  

More details on application equipment and methods can be found in the
AHE400 study report for backpack applications on page 70-71 and Table
BP-6 on pages 102-105 and for handgun applications on page 259 and Table
HG-6 on pages 292-295.

    

Application Rates

According to the Backpack and Handgun ROW Scenario Construction Plan
(AHETF, 2010a) and the AHETF Governing Document (AHETF, 2008 and 2010b),
the total amount of active ingredient applied should be diversified
across the scenario and within each study location.  

For backpack applications, small volumes of liquid concentrate products
(< 1 gallon up to 15 gallons) were mixed with water (7.5 to 400 gallons)
according to label specified dilutions in a tank from which workers
would load the spray into their backpack.  Overall workers sprayed 4.5
to 64.5 gallons of solution in 2 to 11 hours.  

In two cases (MUs A27 and A16) ready-to-use products (i.e., packaged as
diluted solutions) were used so the amount of product in the spray is
the same as the amount of spray prepared.  Also, amounts handled reflect
the “hack-and-squirt” applications conducted by three workers (MUs
A1, A2, and A23) in addition to their backpack applications.

Using the product concentration – determined either by purity analysis
or labeled concentration – with the known dilution and amount sprayed,
the amount of active ingredient handled can be determined.  Backpack
applicators handled from 0.03 to 9.65 lbs of active ingredient.  

Table 5 below provides more detail on backpack application rates.  The
submitted AHE400 study report should also be referenced on page 71 and
Tables BP-6 (pages 102-105) and BP-13 (page 250).

Table 5.  Backpack Application Information

MU ID	Site	Active Ingredient (ai)	Product Conc.

(lb ai / gal)	Amt Product in Spray

(gal)a	Amt Spray Prepared

(gal)	Amt Spray Applied (gal)	Loads Sprayed

(#)	Area Treated

(acres)	Time (hr)	AaiH (lb)b

A27c,d	Distribution	Glyphosate	0.32	5	5	4.5	2	Not recorded	3.5	1.44

A33d	Transmission	Glyphosate	2.67	9.5	160	28.5	10	5.25	9	4.49

A34d	Park	Glyphosate	3	2	100	13.5	4	3.5	2	0.81

A8	Distribution	Fosamine	4.3	5.5	275	12.25	4	4	4	2.11f

A10	Transmission	Glyphosate	4.28	14	400	64.5	17	6	6.4	9.65

A20d	Distribution	Imazapyr	4.19	0.5	210	48	12	0.75	5.1	0.48

A11	Wildlife Refuge	Imazapyr	0.45	1.5	300	22.5	9	3.3	8.2	0.051

A12	Transmission	Glyphosate	4.13	1.35	50	16.5	6	5	5	1.9

A13	Transmission	Glyphosate	4.13	1.35	50	20	7	5	5	2.27

A1d,e	Distribution	Glyphosate	2.67	11	151	33.25	10	2	10.7	6.65

A23e	Distribution	Glyphosate	3.9	8	160	14.5	5	0.45	6	3.11

A24	Transmission	Imazapyr	2.04	1.25	225	33	10	Not recorded	4.3	0.37

A16c,d	Pipeline	Glyphosate	0.32	30	30	15.875	6	3.25	10.2	5.08

A38d	Distribution	Glyphosate	2.07	1.92	32	14.75	5	0.75	8.8	1.83

A31	Park	Glyphosate	3.02	0.4	16.5	16.5	6	0.6	6.3	1.13

A40	Drainage Ditch	Glyphosate	4.07	0.15	7.5	7.5	7	0.9	7.8	0.62

A2d,e	Transmission	Glyphosate	2.67	15	200	16.5	7	0.75	7.5	3.62

A4	Transmission	Imazapyr	1.98	0.28	300	16	6	2	6.1	0.03

A25	Transmission	Glyphosate	4	10	221	19.5	7	1.6	3.6	3.51

a Amount of product includes any removal of small amounts used for
purity analysis.

b Amount active ingredient can be approximated by the calculation: 
product concentration (lb ai/gal product) * amount of product in spray
mixture (gal prod) * [amount of spray mixture applied (gallons) ÷
amount of spray mixture prepared (gallons)].  Slight differences with
the reported value are due to AHETF calculating and summing the amount
ai handled for each load.

c Product was a ready-to-use solution, so gallons of product in spray
mixture and gallons of spray mixture prepared are the same.

d Product was unavailable for sampling or was a “Premix” product –
thus, concentration on label was used for calculation purposes.

e Worker also made “hack-and-squirt” applications.

f Reflects the addition of a total (across 4 backpack loads) of 0.25
gallons (1 lb ai) of the product to the mixture.



For handgun applications, small volumes of liquid concentrate products
(< 1 gallon up to 12 gallons) were mixed with large volumes of water (~
100 to 3100 gallons) according to label specified dilutions.  Workers
then sprayed from 80 to 2900 gallons in about 3 to 11 hours.  Using the
product concentration – determined either by purity analysis or
labeled concentration – with the known dilution and amount sprayed,
the amount of active ingredient handled can be determined.  Handgun
applicators handled from 0.077 to 45.95 lbs of active ingredient. 

Table 6 below provides more detail on backpack application rates.  The
submitted AHE400 study report should also be referenced for handgun
applications on pages 259-260 and Tables HG-6 (on pages 292-295) and
HG-13 (page 449).

Table 6.  Handgun Application Information

MU ID	Site	Active Ingredient (ai)	Product Conc.

(lb ai / gal)	Amt Product in Spray

(gal)a	Amt Spray Prepared

(gal)	Amt Spray Applied (gal)	Loads Sprayed

(#)	Area Treated

(acres)	Time (hr)	AaiH (lb)b

A28c	Trans. + Dist. ROW	Glyphosate	4	5	500	485	1	Not recorded	6.8	19.4

A29c	Trans. ROW	Glyphosate	2.67	6	600	580	3	6.09	6.7	15.49

A30	Trans. ROW	Glyphosate	4.02	5	600	400	2	3	6.6	13.19

A9	Dist. ROW	Fosamine	4.3	5.5	275	188	1	Not recorded	4.8	16.17

A19	Dist. ROW	Imazapyr	2.13	0.75	900	700	3	4.7	8	1.24

A39	Trans. ROW	Imazapyr	3.88	0.31	260	260	1	6.2	5.5	1.21

A6	Trans. ROW	Imazapyr	1.88	2	250	190	3	40	8.4	2.89

A7	Trans. ROW	Glyphosate	4.27	2.7	295	86.5	2	52	9.7	3.54

A36	Trans. ROW	Imazapyr	2.06	1.5	200	190	2	9.7	5.9	3.09

A14	Fence Line	Imazapyr	1.96	0.46	185	144	4	0.36	7.1	0.71

A15	Trans. ROW	Glyphosate	4.18d	6	755	671	13	Not recorded	6.4	21.73

A17	Dist. ROW	Glyphosate	4.23	6.3	315	225	2	3	5.2	19.04

A21	Dist. ROW	2,4-D	2.51	1	200	200	4	1.2	6.6	2.51

A22	Dist. ROW	2,4-D	3.76	2.125	635	635	3	2.2	7.4	7.99

A35	Pipeline Terminal	2,4-D	2.32	3.9	107.5	104.5	7	1.5	8.1	8.87

A26	Roadsides	Glyphosate	4.11	12	3100	2900	2	Not recorded	10.4	45.95

A32	Dist. ROW	Fosamine	3.99	3.5	350	338	6	6.7	8.6	13.49

A37	Dist. ROW	Imazapyr	2.06	0.13	275	80	4	Not recorded	11.4	0.077

A3	Trans. ROW	Imazapyr	1.98	0.26	300	281	1	3	6	0.52

A5	Drainage Ditch	Glyphosate	4.10	2.6	140	81e	2	1	3.3	6.84

A18	Dist. ROW	Glyphosate	4.24	11	1000	900	2	17	6.9	41.98

a Amount of product includes any removal of small amounts used for
purity analysis or for backpack applications.

b Amount active ingredient can be approximated by the calculation: 
product concentration (lb ai/gal product) * amount of product in spray
mixture (gal prod) * [amount of spray mixture applied (gallons) ÷
amount of spray mixture prepared (gallons)].  Slight differences with
the reported value are due to AHETF calculating and summing the amount
ai handled for each load.

c Product was unavailable for sampling or was a “Premix” product –
thus, concentration on label used for calculation purposes.

d Represents the average of two product concentrations: 4.16 and 4.19 lb
ai/gallon.

e AHE400 incorrectly reports this as 71 gallons.



Exposure Monitoring and Analytical Methods

Per applicable AHETF SOPs, standard passive dosimetry methods recognized
by EPA as appropriate for worker exposure monitoring were utilized for
all monitoring.  No biomonitoring samples were collected.  Dermal
exposure to the hands was measured using a hand rinse method
administered at the end of the workday as well as at lunch, restroom
breaks, or other instances where workers would otherwise wash their
hands as outlined in AHETF SOP 8.B.  Dermal exposure to the face/neck
was measured using a wipe technique as outlined in AHETF SOP 8.C and
extrapolated to non-wiped portions of the head according to AHETF SOP
9.K.  Thus, for those workers who wore eye protection and/or hard hats,
the extrapolation to the whole head renders the resulting measurement
somewhat representative of face/neck/head exposure without that
additional gear.  Generally, 1-2 face/neck wipe samples were collected
for each worker then analyzed as a composite sample.

Dermal exposure to the remainder of the body (torso, arms, and legs) was
measured using whole body dosimeters (100% cotton union suits),
sectioned into six pieces and analyzed separately according to AHETF SOP
8.A.  All these measurements combine to reflect dermal exposure
underneath a single layer of work clothing (long-sleeve shirt, pants,
shoes/socks) and chemical-resistant gloves.  Inhalation exposure was
measured using OVS tubes mounted on the worker’s collar and personal
sampling pumps (set at 2 liters per minute) according to AHETF SOP 8.D. 
The concentrations measured represent the chemical available in each
worker’s breathing zone.  The submitted AHE400 study report outlines
the passive dosimetry procedures in more details on pages 14-18.

Validated analytical methods specific to each type of monitoring matrix
(i.e., inner dosimeters, hand rinses, etc.) were used to extract
residues.  The analytical methods are outlined in the analytical
reports:

2.4-D – AHE400 Appendix B, pages 539-647

Fosamine – AHE400 Appendix C, pages 648-760

Glyphosate – AHE400 Appendix D, pages 761-1176

Imazapyr – AHE400 Appendix E, pages 1177-1399.  

Limits of quantification and detection (as defined in AHETF SOP 9.A) are
presented in   REF _Ref280797945 \h  \* MERGEFORMAT  Table  7 below.

Table 7.  Analytical Limits (µg/sample) for AHE400

Monitoring Matrix	Limit of Detection	Limit of Quantification

	2,4-D	Fosamine	Glyphosate	Imazapyr	2,4-D	Fosamine	Glyphosate	Imazapyr

Inner Dosimeter	0.30	0.1701	0.139	0.041	1.0

Socks 	0.060	0.0285	0.011	0.0355	0.25

Hand Rinse	0.30	0.1278	0.179	0.167	1.0

OVS air sampler

(per section)	0.0015	0.0008	0.0016	0.0005	0.005

Face/Neck Wipe	0.30	0.3123	0.143	0.317	1.0



Results

This section provides a discussion of quality assurance and quality
control sampling and the actual field monitoring measurements of
workers.

Quality Assurance

All phases of each study were subject to appropriate quality assurance
processes according to EPA’s GLPs which included an audit by the AHETF
Quality Assurance Unit (QAU) per AHETF SOPs (AHETF SOP Chapter 5:  A-K).
 The inspected phases were:  Protocol, Field Phase, Field Data, Draft
Report, Analytical Data, Final Report, and Post-Audit Report.  The study
contains a signed quality assurance compliance statement as required by
GLPs.  Protocol amendments or deviations were addressed appropriately
under GLP guidance and are described further in Section 4.0.

Quality Control

AHETF instituted various quality control measures to ensure proper field
conduct including calibration of sprayers, preparation and handling of
exposure measurement matrices, evaluation of test material, and field
observations (AHETF SOP Chapter 10:  A-G).  Analytical methods were
validated appropriately ensuring that all exposure matrices could be
measured for the surrogate active ingredients proposed.  Analytical
quality control measures for ensuring the integrity of measurements
captured in the research were also instituted according to AHETF SOP
9.J.  

Exposure monitoring matrices (inner whole body dosimeters, hand washes,
face/neck wipes, OVS tubes) were fortified with known amounts of active
ingredient to assess their stability during field, transit, and storage
conditions according to AHETF SOP 8.E.  Laboratory control samples were
also fortified at the level of quantification and at levels capturing
the range of expected field exposures for each matrix.  Generally, field
fortification samples were collected in triplicate at each of 3 levels
(high, middle, and low) on each sampling day.  Travel fortifications
were generally conducted on each day of sampling in duplicate only at
the high fortification level.  Untreated control samples – included to
determine if there are significant background sources or contamination
during sample processing – were generally conducted in duplicate on
each day of sampling.

The following sections provide results for all quality control sampling
across all exposure measurement matrices for all chemicals used.  The
identified supplemental tables should be referenced for
chemical-specific results.

Field and Laboratory Control Samples

As expected, most non-fortified (blank) laboratory and field control
samples contained no detectable residues.  For field controls,
detectable residues (imazapyr, fosamine, and glyphosate) were infrequent
and found mostly in OVS tubes.  For laboratory controls, imazapyr was
detected in a few inner dosimeter and OVS tubes.  Detections in the OVS
tube control samples are not surprising given the sensitivity of the
method – the LOD ≤ 0.0016 ug/sample, and many were close to that
residue level.  For other dosimeters, the detections were all lower than
the lowest field fortification level tested.  In all cases, both the
frequency and magnitude of these detections did not indicate systematic
contamination; thus, per standard AHETF procedure, no correction was
made to any field monitoring samples based on results of control
samples.  

More detailed results can be found in AHE400:  Appendix B (2,4-D) Tables
7-11 on pages 578-582; Appendix C (Fosamine) Tables 7-11 on pages
689-694; Appendix D (Glyphosate) Tables 11-16 on pages 844-860; Appendix
E (Imazapyr) Tables 11-16 on pages 1241-1252.

Field Fortification Recoveries – Applicable to Both Backpack and
Handgun Exposure Monitoring

Field fortification sampling matrices are spiked with known amounts of
chemical, then placed under similar conditions and duration as the
actual sampling matrices used on the workers (including drawing air
through OVS samplers).  The intent of these samples is to quantify
potential residue losses due to the sampling methods used under actual
field conditions.  Additional samples are also fortified to assess
degradation of the sample during transit from the field to the lab and
during sample storage.  However, per AHETF protocol, these are only
analyzed if anomalous field fortification recoveries indicate potential
degradation during transport and sample storage.  No storage or
transport fortification samples were analyzed since field fortification
results did not indicate any problems related to excessive degradation
of residues.

Field fortifications are conducted at 3 levels to capture the expected
range of results, with triplicate samples taken on each day at each
fortification level.  Once analyzed, the average recovery results
(expressed as a percentage of known amount applied) are used as
multipliers to adjust, or correct, all measured field samples to 100%. 
As the fortification samples are conducted at levels to capture the
range of expected field sample results, adjustments are done using the
average percent recovery for the fortification level closest to the
measured field sample.  The mid-point between each fortification level
is used as the threshold in determining the average recovery percentage
for use in adjusting the field sample.

With some exceptions, field fortification averages for each
fortification level and each monitoring matrix were in the range of
70-120% with coefficients of variation generally less than 25%.  A
summary of field fortification results for each matrix is provided below
in Sections 3.2.3.1 – 3.2.3.4.

Inner Dosimeters and Socks

Results for inner whole body dosimeter (WBD) and sock field
fortification samples were acceptable, with average recoveries ranging
from 70% to 120% and coefficients of variation less than 25%.  

Some atypically high and low average recoveries (~ 9% of all inner
dosimeter and sock fortifications) were observed (48-66% and 121-153%),
mostly for glyphosate fortifications in sock dosimeters.  However,
except for one fortification with a CV=31% (which did not end up being
applicable to any field sample) all other CVs for these atypical results
were less than 25%.  For more details on field fortification results for
inner dosimeters and socks see AHE400 Table BP-11 on pages 216-232 and
Table HG-11 on pages 413-430.

2012:  ≤ 52.5 µg, > 52.5 to ≤ 2,050 µg, and > 2,050 µg

After 2012:  ≤ 252.5 µg, > 252.5 to ≤ 25,250 µg, and > 25,250 µg 


Socks:  

Before 2012:  ≤ 5.5 µg, > 5.5 to ≤ 55 µg, and > 55 µg

After 2012:  ≤ 50.5 µg, > 50.5 to ≤ 2,550 µg, and > 2,550 µg

2,4-D

WBD:  ≤ 252.5 µg, > 252.5 to ≤ 25,250 µg, and > 25,250 µg  

Socks:  ≤ 50.5 µg, > 50.5 to ≤ 2,550 µg, and > 2,550 µg

Face/Neck Wipes

Results for face/neck wipe field fortification samples were acceptable,
with average recoveries ranging from approximately 70% to 120% and
coefficients of variation less than 25%.  Very few (~ 6%) atypical
recoveries (63-68% and 125-149%) were observed, all with CVs less than
25%.  For more details on field fortification results for face/neck
wipes see AHE400 Table BP-11 on pages 216-232 and Table HG-11 on pages
413-430.

Adjustments based on results for each surrogate active ingredient at
each fortification level were applied to field samples falling into the
following ranges.  Specific adjustment factors associated with each of
these ranges can be found in AHE400 in Tables BP-12 on pages 233-249 and
HG-12 pages 431-448.

Glyphosate/Fosamine/2,4-D/Imazapyr

Before 2012:  ≤ 52.5 µg, > 52.5 to ≤ 1,050 µg, and > 1,050 µg

After 2012:  ≤ 52.5 µg, > 52.5 to ≤ 2,550 µg, and > 2,550 µg

Hand Washes

Results for hand wash field fortification samples were acceptable, with
average recoveries ranging from approximately 70% to 120% and
coefficients of variation less than 25%.  Very few (~ 5%) atypical
recoveries (43-64% and 121-124%) were observed (mostly for glyphosate),
all with CVs less than 25%.  For more details on field fortification
results for face/neck wipes see AHE400 Table BP-11 on pages 216-232 and
Table HG-11 on pages 413-430.

Adjustments based on results for each surrogate active ingredient at
each fortification level were applied to field samples falling into the
following ranges.  Specific adjustment factors associated with each of
these ranges can be found in AHE400 in Tables BP-12 on pages 233-249 and
HG-12 pages 431-448.

Glyphosate/Fosamine/2,4-D/Imazapyr

012:  ≤ 52.5 µg, > 52.5 to ≤ 1,050 µg, and > 1,050 µg

After 2012:  ≤ 252.5 µg, > 252.5 to ≤ 5,250 µg, and > 5,250 µg

OVS Air Samplers

Results for OVS field fortification samples were acceptable, with
average recoveries ranging from approximately 70% to 120% and
coefficients of variation less than 25%.  Very few (~ 5%) atypical
recoveries (59% and 124-138%) were observed (mostly for glyphosate), all
with CVs less than 25%.  For more details on field fortification results
for face/neck wipes see AHE400 Table BP-11 on pages 216-232 and Table
HG-11 on pages 413-430.

Adjustments based on results for each surrogate active ingredient at
each fortification level were applied to field samples falling into the
following ranges.  Specific adjustment factors associated with each of
these ranges can be found in AHE400 in Tables BP-12 on pages 233-249 and
HG-12 pages 431-448.

Glyphosate/Fosamine/2,4-D/Imazapyr:  ≤ 2.525 µg, > 2.525 to ≤ 252.5
µg, and > 252 µg

Field Measurements

The following sections summarize the exposure monitoring results,
conducted as described in Section 2.8.  Exposure values reflect total
exposure for workers across their monitoring periods, not normalized by
any exposure metric.  All measurements were appropriately adjusted for
field fortification recoveries (see Section 3.2.2).  Face/neck wipe
measurements were extrapolated to un-wiped portions of the face and head
according to AHETF SOP 9.K.  For samples below the LOQ or LOD, ½ LOQ or
½ LOD was used.

Additionally, in order to account for potential residue collection
method inefficiencies, EPA makes adjustments to hand and face/neck field
study measurements as follows:

if measured exposures from hands, face and neck contribute less than 20%
as an average across all workers, no action is required;

if measured exposure contribution from hands and face/neck represents
between 20% and 60% of total, the measurements shall be adjusted upward
by a factor of 2, or submission of a validation study to support the
residue collection method

if measured exposure contribution from hands and face/neck represents is
greater than 60%, a validation study demonstrating the efficiency of the
residue collection methods is required.

For handgun applicators, the contribution of hands and face/neck
exposures averaged 30% while for backpack applicators, the contribution
averaged 27%.  Therefore the results for exposures to the hands and head
and total dermal exposures outlined in the following sections present
the aforementioned additional 2x adjustment for hand and face/neck
measurements.

 

Inner Dosimeters and Socks

For backpack applicators, without field fortification adjustments,
individual WBD sections ranged from < 0.3 (non-detectable) – 259,830
µg.  Out of a total of 120 inner dosimeter samples, 3 were below the
LOQ and 1 below the LOD.  Sock samples without field fortification
adjustments ranged from 0.95 – 3,959 µg.  No sock dosimeter sample
was below the LOQ or LOD.  AHE400 Tables BP-14 and BP-15 on pages
251-252 provide more details on these samples.  After adjusting for
field fortification recoveries and summing the six separate body
sections, the total dermal exposure underneath the long-sleeve shirt and
pants ranged from 6 – 730,551 µg with an average of 66,760 µg.  Sock
dosimeters with field fortification adjustments ranged from 1 – 3,884
µg with an average of 679 µg.

 

For handgun applicators, AHE400 presents results for WBD and sock
samples without field fortification adjustments.  Individual WBD
sections ranged from < 1.0 (non-detectable) – 49,165 µg.  Out of a
total of 126 inner dosimeter samples, 1 was below the LOQ.  Sock samples
ranged from 0.25 – 6,117 µg.  Only 1 sock dosimeter sample out of 21
was below the LOQ.  AHE400 Tables HG-14 and HG-15 on pages 450-451
provide more details on these samples.  After adjusting for field
fortification recoveries and summing the six separate body sections, the
total dermal exposure underneath the long-sleeve shirt and pants ranged
from 44 – 98,905 µg with an average of 8,497 µg.  Sock dosimeters
ranged from 0.13 – 6,185 µg with an average of 548 µg.

Face/Neck Wipes

For backpack applicators face/neck wipe samples ranged from < 0.3
(non-detectable) – 549 µg without field fortification adjustments. 
Out of 19 face/neck wipe samples, 1 was below the LOQ.  AHE400 Table
BP-15 on page 252 provides more details on these samples.  For handgun
applicators these ranged from 1.6 – 2,160 µg without field
fortification adjustments.  No face/neck wipe sample was below the LOQ
or LOD.  AHE400 Table HG-15 on pages 451 provides more details on these
samples.

Because some workers wore eye protection and because measurements cannot
be easily conducted on hair, extrapolations from those portions of the
face/neck that are wiped need to be made to portions of the head that
are not measured.  Specifics on these adjustment factors can be found in
AHETF SOP 9.K.  Additionally, as previously described, the measurements
are further adjusted upward by EPA by a factor of 2 to account for
potential inefficiencies in residue collection by the wipe technique.

For backpack applicators, after adjusting for field fortification
recoveries and extrapolating to non-wiped portions of the head described
above, total head exposure ranged from 0.8 – 943 µg with an average
of 200 µg.  Including the 2X adjustment by EPA for potential method
collection inefficiencies, total head exposure ranged from 1.6 – 1,886
µg with an average of 399 µg.

For handgun applicators, after adjusting for field fortification
recoveries and extrapolating to non-wiped portions of the head described
above, total head exposure ranged from 3 – 4,347 µg with an average
of 500 µg.  Including the 2X adjustment by EPA for potential method
collection inefficiencies, total head exposure ranged from 6 – 8,694
µg with an average of 999 µg.

Hand Washes

Per protocol, hand washes were collected at the end of each work day and
at points where workers would normally wash their hands such as during
restroom or lunch breaks.  Most workers had 2 hand wash samples taken;
one handgun applicator had 4 hand washes and one backpack applicator had
5 hand washes.  A few workers, despite having relatively long work days
(i.e., 4-8 hours) did not take any breaks and thus only had the 1 hand
wash sample conducted at the end of their workday.  The following table
outlines the number of hand wash samples broken down by the work
duration.  

≥ 8

Backpack	Percentage of Workers	16%	26%	32%	26%

	# of Hand Washes	1-2	1-3	1-2	2-5

Handgun	Percentage of Workers	5%	19%	43%	33%

	# of Hand Washes	1	1-2	1-4	2-3



For backpack applicators, individual hand wash samples ranged from 3.5
– 8,404 µg without field fortification adjustments.  No hand wash
sample was below the LOQ or LOD.  AHE400 Table BP-15 on page 252
provides more details on these samples.  For handgun applicators,
individual hand wash samples ranged from < 1.0 – 3,042 µg without
field fortification adjustments.  Out of a total of 43 hand wash
samples, 1 was below the LOQ.  AHE400 Table HG-15 on page 451 provides
more details on these samples.

For backpack applicators, after adjusting for field fortification
recoveries and summing hand washes for each worker, the total hand
exposure ranged from 13 – 10,776 µg with an average of 2,788 µg. 
Including the 2X adjustment by EPA for potential method collection
inefficiencies, total hand exposure ranged from 26 – 21,552 µg with
an average of 5,575 µg.  

For handgun applicators, after adjusting for field fortification
recoveries and summing each hand wash, the total hand exposure ranged
from 4 – 4,473 µg with an average of 1,194 µg.  Including the 2X
adjustment by EPA for potential method collection inefficiencies, total
hand exposure ranged from 8 – 8,946 µg with an average of 2,387 µg. 


OVS Air Samplers/Inhalation Exposure

Front and back sections of the OVS tube were analyzed separately.  Most
back section samples were less than the LOD, with a few less than the
LOQ.  All front section samples had detected residues.  Inhalation
exposure results were invalidated for two backpack applicators due to
sampling pump failure (MU A27) and lack of remaining sample for analysis
(MU A1 – sample extract was used up from previous analysis with an
improper analytical method).

For backpack applicators, OVS front sections ranged from 0.0466 –
59.66 µg without field fortification adjustments.  AHE400 Table BP-16
on page 253 has more details on these results.  After adjusting for
field fortification recoveries, the total (front section + back section)
collected active ingredient amounts ranged from 0.07 – 67 µg with an
average of 12 µg.

For handgun applicators, OVS front sections ranged from 0.0219 – 77.79
µg without field fortification adjustments.  AHE400 Table HG-16 page
452 has more details on these results.  After adjusting for field
fortification recoveries, the total (front section + back section)
collected active ingredient amounts ranged from 0.03 – 80 µg with an
average of 11 µg.  

The above described results for the amount of active ingredient
collected by the air sampling units.  The AHE400 report – as it is
mainly a presentation of field and analytical results – presents only
total active ingredient collected by the air sampling units.  Separate
AHETF monograph submissions (under separate EPA reviews) present worker
inhalation exposures applying an assumed breathing rate.  To calculate
worker inhalation exposures, the measured amounts are adjusted based on
the pump flow rate (in liters per minute) and a typical worker’s
breathing rate for this type of activity.  For these studies a breathing
rate of 16.7 liters per minute was used, representing light activities
(NAFTA, 1998).  The calculation is as follows:

Inhalation exposure = Adjusted residue (µg) * [Breathing rate (LPM) ÷
Pump flow rate (LPM)]

For backpack applicators, worker exposures ranged from 0.54 – 567 µg
with an average of 100 µg.  For handgun applicators, worker exposures
ranged from 0.24 – 670 µg with an average of 88 µg.  

Exposure Calculations

This section provides total exposures (expressed as mass active
ingredient), as well as exposures normalized to (i.e., dividing by) body
weight and amount of active ingredient handled (AaiH).

Dermal Exposures

Total dermal exposure, calculated by summing the results for inner
dosimeters, hand washes and face/neck wipes, are presented below as well
as normalized to body weight and amount of active ingredient handled. 
Results are presented both
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(μg)	Normalized by Body Weight

(μg/kg BW)	Normalized by Amount ai Handled

(μg/lb ai)



MEA	Non-MEA	MEA	Non-MEA	MEA	Non-MEA

Backpack	Minimum	34	20	0.48	0.28	675	400

	Maximum	752,379	742,664	8,360	8,252	241,923	238,799

	Mean	73,414	70,426	855	819	31,273	30,110

Handgun	Minimum	80	66	1.06	0.88	26	17

	Maximum	112,258	108,674	1515	1,467	12,123	11,365

	Mean	12,431	10,738	156	135	1,868	1,654

Note:  Means are simple averages (i.e., sum of values ÷ n)



Inhalation Exposures

As shown in Section 3.3.4, inhalation exposure is calculated based on
the chemical in air over the monitoring period, the pump flow rate, and
the worker’s breathing rate.  Results are presented below.

  

Table 10.  Inhalation Exposure Summary

Equipment	Statistic	Total Exposure

(μg)	Normalized by Body Weight

(μg/kg BW)	Normalized by Amount ai Handled

(μg/lb ai)

Backpack	Minimum	0.54	0.007	1.74

	Maximum	567	7	112

	Mean	100	1.22	35

Handgun	Minimum	0.24	0.003	0.18

	Maximum	670	8.28	35

	Mean	88	1.09	7

Note:  Means are simple averages (i.e., sum of values ÷ n)



Field Observations

Field researchers observed each worker and recorded their behavior
throughout the work day.  These can be found in the AHE400 report in
Table BP-9 on pages 112-174 and HG-9 on pages 302-369.

Much of the observations detailed routine application procedures (e.g.,
MU A27 @ 0815:  “Sprayed a ~20 ft. section of high brush along side of
road.”).  Other observations may potentially provide clues as to
determinants of exposure – examples of these types of observations
include:

Overhead spraying – e.g., MU A33 @ 0902: “Sprays a birch tree (~5
ft. tall) on hillside, which requires overhead spraying. Large visible
plume, moderate contact with A33”;

Contact with treated foliage – e.g., MU A10 @ 1102:  “A10 observed
walking directly into just sprayed foliage (below waist high)”;

Getting off truck to walk and spray target area (handgun) – e.g., MU
A22 @ 0918:  “A22 down from truck, walking along ROW area, spraying
into ROW.”

EPA reviewed the field observations for potential clues as to
determinants of exposure or potential reasons for high exposures. 
Though difficult to quantify in this fashion, some additional analysis
where field observations were reviewed in a quantitative fashion, refer
to the scenario monograph reviews (Crowley, 2015a and Crowley, 2015b). 
Data users are recommended to review the field observations to get a
sense of the extent of activities within these exposure scenarios.  

Protocol Amendments and Deviations

Amendments to and deviations from the study protocol are detailed below.
 For additional details, see the AHE400 study report on pages 11-14 as
well as Appendix A on pages 504-538.  The study amendments were
reasonable accommodations to accomplish the research and deviations did
not adversely impact the study conduct or the exposure monitoring
results.

Protocol Amendments:

To increase likelihood of finding workers to monitor, additional
employer sources were added:  the same employer can be used in multiple
monitoring areas; referrals from other employers; and,
employers/companies the AHETF is aware of but not on the “Employer
Universe List”.

Because recruitment revealed that workers commonly wear chaps and
leggings for physical protection, this was removed as an exclusion
criterion.

Because recruitment revealed that workers commonly wear (or are required
by their employers to wear) hard hats and boots that rise above
mid-calf, those were removed as exclusion criteria.

Because recruitment specifically for electric and pipeline utility
rights-of-way proved limiting, additional areas of similar brush/shrubs,
foliage density/height, and terrain such as roadsides and wildlife
refuges were added as possible sites.

Amended contact information for Principal Analytical Investigator and
Analytical Facility

Amended fosamine and imazapyr analytical methods sections to more
accurately identify the methods following their complete development and
validation.

Recruitment in the originally specified US states proved limiting, other
states will be acceptable.

Field fortification levels for dermal exposure monitoring methods were
increased.

Recruitment proved difficult, so the “same employer” restriction was
relaxed – but with additional restrictions that if they had the same
employer monitoring must occur in a separate year, a different job site,
and a different application crew.

Changed glyphosate analytical methods following addition of a
derivatization step and added additional text specifying how this
revised method was validated.

Protocol Deviations

Field samples for MUs A8 and A9 as well as associated field
fortification levels were analyzed for fosamine using analytical methods
not fully identified in the protocol or by a protocol amendment.  Though
not identified in the protocol or amendment, at the time of analysis the
method had been validated and finalized.

Unavailability of test substances for purity analysis.  Amount of active
ingredient handled determined from product label and dilution rates.

Instances of less than 4 hours of monitoring time.  Other application
characteristics (tank loads, gallons sprayed, etc.) were still adequate
and representative of typical workdays.

Lack of hand wash collection preceding a cigarette break.

Use of applicator’s own chemical-resistant gloves rather than
AHETF-supplied chemical-resistant gloves.

Failure to inform application company representative that they would
receive an AHETF introductory letter.

Inhalation exposure pump off for extended periods of (non-exposure) time
such as lunch breaks or rain events.

Lack of documentation of changes to analytical laboratory facilities.

Conclusion

As the studies followed their corresponding protocols as well as EPA
guidelines for occupational pesticide exposure monitoring, the results
are reliable for assessment of exposure and risk for backpack and
handgun applications in utility rights-of-ways and other areas where
chemical control of similar undesirable vegetation is conducted.

Since these exposure data were collected with the intention to populate
a generic pesticide exposure database, reviewers are directed to the
additional information and statistical analyses in the AHETF Handgun ROW
Scenario Monograph (Bruce, et al, 2014a) and the AHETF Backpack ROW
Scenario Monograph (Bruce, et al, 2014b).  

Review of those monographs as well as recommendations for use of the
data by EPA exposure assessors are in a separate review memorandum
(Crowley, 2015a and 2015b).

References

AHETF, (2008).  Volume IV AHETF Revised Governing Document for a
Multi-Year Pesticide Handler Worker Exposure Monitoring Program. 
Version Number:  1. April 7, 2008.  Agricultural Handlers Exposure Task
Force (AHETF). [MRID 47172401]

AHETF, (2010a).  Monitoring Unit Selection and Construction Plan for
Scenarios:  1. BACKPACK APPLICATION OF LIQUID SPRAYS IN UTILITIES
RIGHTS-OF-WAY 2.  HANDGUN APPLICATION OF LIQUID SPRAYS IN UTILITIES
RIGHTS-OF-WAY.  June 4, 2010.

AHETF, (2010b).  Governing Document for a Multi-Year Pesticide Handler
Exposure Monitoring Program, Version 2, August 12, 2010.

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摧⊱ýᜀBruce, E. (2014).  Determination of Dermal and Inhalation
Exposure to Workers during Backpack and Handgun Application of Liquid
Sprays in Utilities Rights-of-Way.  Study Number AHE400.  Unpublished
study sponsored by the Agricultural Handler Exposure Task Force.  1430
p.  September 18, 2014.  EPA MRID 49472001.

Bruce, E., Holden, L., and Klonne, D. (2014a).  Agricultural Handler
Exposure Scenario Monograph:  Handgun Application of Liquid Sprays in
Utilities Rights-of-Way.  Report Number AHE1013.  Unpublished study
sponsored by the Agricultural Handlers Exposure Task Force.  218 p. 
September 29, 2014.  EPA MRID 49478602.

Bruce, E., Holden, L., and Klonne, D. (2014b).  Agricultural Handler
Exposure Scenario Monograph:  Backpack Application of Liquid Sprays in
Utilities Rights-of-Way.  Report Number AHE1012.  Unpublished study
sponsored by the Agricultural Handlers Exposure Task Force.  224 p. 
September 29, 2014.  EPA MRID 49478601. 

Crowley, M. (2015a).  Memorandum:  Review of Agricultural Handler
Exposure Task Force (AHETF) Monograph:  “Backpack Application of
Liquid Sprays in Utilities Rights-of-Way” (AHE1012).  D424145.  March
24, 2015.

Crowley, M. (2015b).  Review of Agricultural Handler Exposure Task Force
(AHETF) Monograph:  “Handgun Application of Liquid Sprays in Utilities
Rights-of-Way” (AHE1013).  D424145.  March 24, 2015.

NAFTA - Dept. of Pesticide Regulation (DPR), California EPA, HSM-98014,
April 24, 1998.

 All dermal exposure values reflect a 2X adjustment on hand rinse and
face/neck wipe measurements accounting for assumed 50% residue
collection method efficiency (see Section 3.3).  Non-adjusted values are
available in associated review spreadsheets.

 Inhalation exposure (μg) = Residue collected * [Breathing rate (L/min)
÷ Pump rate (L/min)].  Pump rates generally were 2 L/min.  Note: 
AHE400 presented the total active ingredient collected (μg), not
results adjusted for breathing rates as shown here.  AHETF monograph
submissions, reviewed separately, perform the calculation shown here. 

 NAFTA, 1998.  Rate of 16.7 L/min represents light activity.

 In 2012 fortification levels for dermal dosimetry were increased to
accommodate field samples that exceeded the highest fortification level.

 Per AHETF standard procedure, if average recovery is > 120% the maximum
(“downward”) adjustment value applied is 1.2. 

  The terminology used to describe this are “method efficiency
adjusted” (MEA) or “method efficiency corrected” (MEC).  Previous
AHETF submissions included these adjustments but they have indicated
that they will no longer continue to do so.  Thus these adjustments are
instead made by EPA.

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