                    UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                         WASHINGTON, D.C. 20460      

                                                	OFFICE OF CHEMICAL SAFETY AND 
                                                           POLLUTION PREVENTION
	


MEMORANDUM

Date: 	March 29, 2018


SUBJECT:	Dithiopyr: Tier I Update Review of Human Incidents and Epidemiology for Draft Risk Assessment

PC Code: 128994
DP Barcode: D445956
Decision No.: 528348
Registration No.: NA
Petition No.: NA
Regulatory Action: NA
Risk Assessment Type: NA
Case No.: NA
TXR No.: NA
CAS No.: 97886-45-8
MRID No.: NA
40 CFR: NA
		              									Ver.Apr.08
	          	
FROM:	Shanna Recore, Industrial Hygienist	
		Elizabeth Evans, Environmental Protection Specialist
		Toxicology and Epidemiology Branch
		Health Effects Division (7509P)
						
THROUGH:	David J. Miller, Acting Branch Chief
		Toxicology and Epidemiology Branch
		Health Effects Division (7509P)
			
TO: 		Monica Hawkins, Risk Assessor
		Risk Assessment Branch VI
		Health Effects Division (7509P)
			and				
            V. Dutch, Chemical Review Manager
		Risk Management & Implementation Branch 5
		Pesticide Re-evaluation Division (7508P)

Summary and Conclusions

Dithiopyr incidents were previously reviewed in 2013 (E. Evans and S. Recore, D415250, 09/24/13).  At that time, based on the low severity and frequency of cases reported to both Incident Data System (IDS) and NIOSH Sentinel Event Notification System for Occupational Risk (SENSOR)-Pesticides, there was not a risk of concern that warranted further analysis.

In the current IDS analysis from January 1, 2013 to March 1, 2018, two cases involving a single active ingredient and four cases involving multiple active ingredients were reported to Main IDS; there were 36 cases reported to Aggregate IDS.  A query of SENSOR-Pesticides 1998-2014 identified 25 cases involving dithiopyr.  

The Agricultural Health Study (AHS) is a federally-funded study that evaluates associations between pesticide exposures and cancer and other health outcomes and represents a collaborative effort between the US National Cancer Institute (NCI), National Institute of Environmental Health Sciences (NIEHS), CDC's National Institute of Occupational Safety and Health (NIOSH), and the US EPA.  Dithiopyr is not included in the AHS, and therefore this study does not provide information for this report.

Based on the continued low frequency and severity of dithiopyr incidents reported to both IDS and SENSOR-Pesticides, there does not appear to be a concern at this time.  The Agency will continue to monitor the incident data and if a concern is triggered, additional analysis will be conducted.

Detailed Review 

 ACTION REQUESTED

Dithiopyr is being considered under the FQPA-mandated Registration Review program established to review, on a 15-year cycle, pesticides for which a Re-registration Eligibility Decision has been made.  HED's RAB VI has requested that TEB conduct a Tier I Update review summary of recent incident data from IDS and SENSOR as per standard protocol under the Agency's Registration Review Program. One component of the Agency's Registration Review Program is consideration of human incident data.  In conjunction with a human health risk assessment based on other data sources, such human incident data can assist the Agency in better defining and characterizing the risk of pesticides/pesticide products.  

It is important to remember that reports of adverse health effects allegedly due to a specific pesticide exposure (i.e., an "incident") are largely self-reported and therefore, generally speaking, neither exposure to a pesticide or reported symptom (or the connection between the two) is validated or otherwise confirmed.  Typically, causation cannot be determined based on incident data, and such data should be interpreted with caution.  Nonetheless, incident information can be an important source of feedback to the Agency:  incidents of severe outcome, or a suggested pattern or trend among less severe incidents, can signal the Agency to further investigate a particular chemical or product. Epidemiology studies can also be useful and relate the risk of disease, e.g., cancer, and exposure to an agent such as a pesticide product in the general population or specific sub-groups like pesticide applicators.  

 BACKGROUND		

Dithiopyr is a pre-emergent herbicide for control of grasses and small-seeded broad leaf weeds. Its primary use in is to control crabgrass in turf, ornamentals, and flowerbeds.

For this evaluation, both OPP Incident Data System (IDS) and the Centers for Disease Control and Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) Sentinel Event Notification System for Occupational Risk-Pesticides (SENSOR) databases were consulted for pesticide incident data on the active ingredient dithiopyr (PC Code:128994).  The purpose of the database search is to identify potential patterns in the frequency and severity of the health effects attributed to dithiopyr exposure.  

 RESULTS/DISCUSSION
 IDS (Incident Data System)

OPP's IDS includes reports of alleged human health incidents from various sources, including mandatory Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) Section 6(a)(2) reports from registrants, other federal and state health and environmental agencies, and individual consumers. Since 1992, OPP has compiled these reports in IDS.  IDS contains reports from across the U.S. and most incidents have all relevant product information recorded. Reports submitted to the IDS represent anecdotal reports or allegations only, unless otherwise stated in the report.  

IDS records incidents in one of two modules: Main IDS and Aggregate IDS:
  
 Main IDS generally contains incidents resulting in higher severity outcomes and provides more detail with regard to case specifics.  This system stores incident data for death, major and moderate incidents, and it includes information about the location, date and nature of the incident.  Main IDS incidents involving only one pesticide are considered to provide more certain information about the potential effects of exposure from the pesticide. 
            
 Aggregate IDS contains incidents resulting in less severe human incidents (minor, unknown, or no effects outcomes). These are reported by registrants only as counts in what are aggregate summaries. 
For the Main IDS for the five years from January 1, 2013 to March 1, 2018, there were six cases reported that involved the active ingredient dithiopyr.  Of these six case reports, two incidents involved the single active ingredient dithiopyr (only). These incidents were classified as moderate severity.  The other four dithiopyr incidents reported involved multiple active ingredients.   
For Aggregate IDS for the five years from January 1, 2012 to April 28, 2017, there were 36 incidents reported involving dithiopyr.  Thirty-three of these incidents were classified as minor severity and three had no or unknown severity. 

 SENSOR-Pesticides

The Center for Disease Control's National Institute for Occupational Safety and Health (CDC/NIOSH) manages a pesticide surveillance program and database entitled the Sentinel Event Notification System for Occupational Risk (SENSOR)-Pesticides.  This database includes pesticide illness case reports from multiple states from 1998-2014.   Currently participating states are: California, Florida, Illinois, Louisiana, Michigan, Nebraska, New Mexico, North Carolina, Oregon, Texas and Washington. The participating states for a given year vary depending on state and federal funding for pesticide surveillance. 

Cases of pesticide-related illnesses in the SENSOR-Pesticides database are ascertained from a variety of sources, including: reports from local Poison Control Centers, state Department of Labor workers' compensation claims when reported by physicians, reports from state Departments of Agriculture, and physician reports to state Departments of Health. Although both occupational and non-occupational incidents are included in the database, the SENSOR coordinators primarily focus their follow-up case investigation efforts on the occupational pesticide incidents.  The SENSOR-Pesticides coordinator at the state Department of Health will follow-up with cases and work to obtain medical records in order to verify exposure scenario, symptoms, severity, and health outcome.  Using standardized protocol and case definitions, SENSOR-Pesticides coordinators enter the incident interview description provided by the case, medical report, physician and patient into the database. 

All SENSOR-Pesticide cases must report a minimum of two health effects in order to be included in the aggregate database that EPA uses for incident analyses.  Evidence for each case is evaluated for its causal relationship between exposure and illness based on the NIOSH case classification index.  About 98% of SENSOR-Pesticides cases are classified as definite, probable, or possible, and 2% of the cases are classified as suspicious.  Unlikely, asymptomatic, and unrelated cases, as well as those with insufficient information, are not included in the SENSOR-Pesticides database.  

A query of SENSOR-Pesticides from 1998-2014 identified a total of 25 cases involving dithiopyr (pc code 128994).  Seven cases involved a single active ingredient and 18 cases involved multiple active ingredients.  Fifteen cases occurred in occupational settings and ten cases were residential.  Six cases were moderate in severity and 19 cases were low in severity.  

The most frequently implicated product, involved in nine of the 25 dithiopyr incident reports in SENSOR, was Roundup Ready-to-use Extended Control Weed & Grass Killer 1 Plus Weed, EPA Reg. No. 71995-21, an actively registered product that contains 0.03% dithiopyr and 1% glyphosate. 

The following summarizes the exposure scenarios for all 25 dithiopyr cases:
 Eleven cases were exposed while applying a product containing dithiopyr.  
 Seven cases involved various (non-application) handling exposure scenarios, including:
 Four cases involved exposure during the vehicle transportation of the chemical. 
 Three of these eight cases were retail workers at lawn and garden centers were exposed when handling products purchased by consumers.  One of the three retail exposures was a cashier who got some of the pesticide in her eyes while checking out a customer, another retail worker was stacking bags of product when exposed, and a store manager was splashed in the eye when disposing of a returned product.  
 Two cases were exposed and made ill due to their close proximity to applications that were taking place; one case was in their home and the other case was working at a university.
 One case was working on a golf course that was treated with Roundup (product has 0.03% dithiopyr and 1% glyphosate).
 One case was a child that grabbed a product from a shelf at a retail establishment and sprayed himself in the eye. 
 In three cases the exposure scenarios were unknown.
Health effects reported among cases primarily involved the nervous system, followed by ocular and dermal effects.  The specific symptoms most reported were headache and eye pain/irritation.  

 Agricultural Health Study (AHS)
            
The AHS is a federally-funded study that evaluates associations between pesticide exposures and cancer and other health outcomes and represents a collaborative effort between the US National Cancer Institute (NCI), National Institute of Environmental Health Sciences (NIEHS), CDC's National Institute of Occupational Safety and Health (NIOSH), and the US EPA. The AHS participant cohort includes more than 89,000 licensed commercial and private pesticide applicators and their spouses from Iowa and North Carolina. Enrollment occurred from 1993  -  1997, and data collection is ongoing. The AHS maintains a list of publications resulting from AHS studies. If there are AHS findings in the published literature relevant to a pesticide undergoing registration review, the Agency will ensure these findings are considered in the problem formulation/scoping phase of the registration review process and, if appropriate, fully reviewed in the risk assessment phase of the process.  Dithiopyr is not included in the AHS, and therefore this study does not provide information for this report.

 CONCLUSION

Based on the continued low frequency and severity of dithiopyr incidents reported to both IDS and SENSOR-Pesticides, there does not appear to be a concern at this time.  The Agency will continue to monitor the incident data and if a concern is triggered, additional analysis will be conducted.

