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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION

MEMORANDUM

Date: September 24, 2013

SUBJECT: Dithiopyr: Tier I Review of Human Incidents

PC Code: 128994 DP Barcode:0415250

Decision No.: 481487

Petition No.: NA

Risk Assessment Type:NA 

TXRNo.:NA

MRID No.: NA

Registration No.: NA 

Regulatory Action: NA 

Case No.: NA

CAS No.: 97886-45-8

40CFR:NA

Ver.Apr.08

FROM: Elizabeth Evans, Environmental Protection Specialist 

Toxicology and Epidemiology Branch cj tf... 

Health Effects Division (7509P) VJ

Shanna

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core,Industrial Hygienist -1

Toxicology and Epidemiology Branch ·(j1...JLHealth Effects Division (7509P)

I /i,) /;:;JJ li;/J_ruJl.:J

THROUGH: David J. Miller, Acting Branch Chief !. v //1J1

Toxicology and Epidemiology Branch ·

Health Effects Division (7509P)

TO: William Donovan,Risk Assessor 

Risk Assessment Branch V 

Health Effects Division (7509P)

and

V. Dutch, Chemical Review Manager

Risk Management & Implementation Branch 5

Pesticide Reevaluation Division (7508P) 

Summary and Conclusions

Based on the low frequency and severity of incident cases reported for Dithlopyr in both IDS and

NIOSH SENSOR-Pesticides, there does not appear to be a concern at this time that would 

warrant further investigation. The Agency will continue to monitor the incident information and 

if a concern is triggered, additional analysis will be included in the risk assessment.
The Agricultural Health Study (AHS) is also a potential source of information associated with 

human health effects associated with certain pesticides. Dithiopyr is not included in the AHS, 

and therefore this study does not provide information for this report.

Detailed Review

I. ACTION REQUESTED

This review is intended to fulfill our requirement to docket summaries of incident data that were 

reported to the Agency, as well as to ensure human incident data and the Agricultural Health 

Study (AHS) are part ofthe problem formulation phase of registration review. 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. However, 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. Observational epidemiology studies 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.

II. 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 the 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. Dithiopyr is not included in the AHS, and 

therefore this study does not provide information for this report.

III. RESULTS/DISCUSSION

a. 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. It should be noted there are two incidents reported as lawsuits to IDS that are not 

considered in this report.

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IDS records incidents in one of two modules: Main IDS and Aggregate IDS:

o Main IDS 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 

active ingredient (as opposed to pesticide products with multiple active 

ingredients) are considered to provide more certain information about the 

potential effects of exposure from the pesticide.

o 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, from January 1, 2008 to June 11, 2013, there were 4 incidents reported for 

single chemical only in the database. There were 8 additional incidents reported involving more 

than one chemical. These incidents were classified as moderate severity. Overall, there are few 

incidents involving dithiopyr reported to IDS.

In Aggregate IDS, from January 1, 2008 to June 11,2013, there were 108 reported incidents 

involving dithiopyr.

b. SENSOR-Pesticides

The SENSOR-Pesticides database covers 11 states from 1998-2009, although reporting varies 

from state to state. Cases of pesticide-related illnesses 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, SENSOR-Pesticides focuses on 

occupational pesticide incidents, and is of particular value in providing that information. The 

state coordinator at each of the 11 respective state Departments of Health conducts case followup activities such as obtaining medical records to verify symptoms and severity. Using 

standardized protocol and case definitions derived from poison center reporting, the state

SENSOR-Pesticide coordinator enters the incident information into the state-based system which 

is sent to NIOSH annually to be aggregated.

A query of SENSOR-Pesticides 1998-2009 identifies 17 cases, stemming from 17 events, 

involving dithiopyr. Seven of the cases were single active ingredients and will be discussed 

here. Of these, one was moderate in severity and six were low in severity. Five were workrelated and two were not. Two of the 5 work-related cases were employees of retail

establishments made illfrom exposure when handling packaged products; one case was shelving

merchandise and one was a cashier at checkout.
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One low severity, work-related case included the following case description, "A 25 year-old 

male golf course worker was mixing Dimension Ultra WSP (a turf and ornamental herbicide) in

a 300 gallon capacity tank. It was a very windy day and, as he poured the powder into the tank of 

water, some blew into his eyes. He was not wearing goggles but reports he usually does. He was 

wearing contact lenses. Reportedly, he was also wearing a Tyvek spray suit with a hood, latex 

gloves, rubber boots and a half-mask respirator, with the appropriate cartridges. He was fit-tested 

for his respirator. He is a turf grass management college graduate and is a certified pesticide 

applicator in the state of Colorado. He currently works under the supervision of a NYS certified 

applicator."

A summary of reported symptoms is provided in Table 2.

Table 2. SENSOR-Pesticides 1998-2009:Reported

Health Effects for single ai Dithiopyr Cases (N=7)

Health Effect # of TimesReported

Dennal 2

Ocular 2

Respiratory 1

Gastrointestinal 3

Renal 0

Nervous System 4

Cardiovascul ar 1

Miscellaneous I

* Cases may report multiple health effects

c. Agricultural Health Study (AHS)

The AHS is a high quality, prospective epidemiology study evaluating the link between pesticide 

use and various health outcomes including cancer. The AHS includes private and commercial 

pesticide applicators and their spouses. If there are AHS findings relevant to a particular

pesticide going through registration review, the Agency will ensure they are considered in the 

problem formulationlscoping phase of the process and, if appropriate, fully reviewed in the risk 

assessment phase of the process. The AHS includes information on use of 50 different pesticide 

active ingredients commonly used in agriculture. Dithiopyr is not included in the AHS, and 

therefore this study does not provide information for this report.

IV. CONCLUSION
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Based on the low frequency and severity of incident cases reported for Dithiopyr in both IDS and 

SENSOR-Pesticides, there does not appear to be a concern at this time that would warrant further 

investigation. The Agency will continue to monitor the incident information and if a concern is 

triggered, additional analysis will be included in the risk assessment.