UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

Date: August 20, 2013 

SUBJECT: Dimethyl disulfide (DMDS): Tier I Review of Human Incidents 

PC Code: 029088 DP Barcode: 0413869 

Decision No.: 479821 

Petition No.: NA 

Risk Assessment Type: NA 

TXRNo.:NA 

MRIDNo.:NA 

Registration No.: NA 

Regulatory Action: NA 

Case No.: NA 

CAS No.: 624-92-0 

40CFR: NA 

Ver.Apr.08 

Elizabeth Evans, Environmental Protection Specialist . ~- {) FROM: 

T

Health 

oxicology 

Effects 

and 

Division 

Epidemio

(7509P) 

logy Branch 

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J-'1~ .. ~ 

· · 

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and 

Shanna Recore, Industrial Hygienist 

Toxicology and Epidemiology Branch 

Health Effect Division (7509P) 

THROUG avid Miller, Acting Branch Chief 

Toxicology and Epidemiology Branch 

Health Effects Division (7509P) 

TO: Shalu Shelat, Risk Assessor 

Risk Assessment Branch VI 

Health Effects Division (7509P) 

and 

Andrea Mojica, Chemical Review Manager 

Risk Management & Implementation Branch 2 

Pesticide Re-evaluation Division (7508P) 

Summary and Conclusions 

Based on the low frequency and severity of incident cases reported for, 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. 

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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 of the 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 

Dimethyl disulfide (DMDS) is a soil fumigant. It is applied by shank injection, broadcast, or by 

drip irrigation to raised beds. DMDS applications are made pre-plant to fields that will be used 

to grow berry (blueberry and strawberry), cucurbit vegetable (cucumber, squash, and melon), 

fruiting vegetable (tomato, pepper, and eggplant), field-grown ornamental, and forest tree 

nursery crops. These treatments are intended to control weeds such as nutsedge (purple and 

yellow), chickweed, lambsquarters, purslane, and grasses; soil-borne plant pathogens such as 

Verticillium spp., Fusarium spp., Pythium spp., Sclerotinia spp., and Rhizoctonia spp.; and 

nematodes such as Root Knot (Southern, Northern, and Colombian), Stubby Root, Lesion, Stunt, 

and Sting. 1 

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 DMDS (pc code: 029088). The 

purpose of the database search is to identify potential patterns in the frequency and severity of 

the health effects attributed to DMDS exposure. DMDS 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 

1 Excerpt from the DMDS Fact Sheet, found online at: 

http://www.epa.gov/pesticides/chem search/reg actions/pending/fs PC-029088 09-Jul-1 O.pdf 

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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: 

o Main IDS contains incidents resulting in higher severity outcomes and provides 

more detail with regard to case specific. 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. 

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 was 1 incident reported for 

single chemical only in the database. This incident was classified as moderate severity. There 

were 2 additional incidents reported involving more than one chemical. These incidents were 

classified as minor severity. Overall, there are few incidents involving DMDS reported to IDS. 

In Aggregate IDS, from January 1, 2008 to February 19, 2013, there were 0 reported incidents 

involving DMDS. 

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 finds no cases involving DMDS. 

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 

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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 formulation/seeping 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. DMDS is not included in the AHS, and 

therefore this study does not provide information for this report. 

IV. CONCLUSION 

Based on the low frequency and severity of incident cases reported for DMDS 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. 

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