UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

Date: April 29, 2015 

SUBJECT : Hexazinone: Tier I Update Review ofi-Iuman Incidents/Epidemiology for Draft 

Risk Assessment 

PC Code: I 0720 I DP Ba rcode: 0427025 

Decision No.: 498287 

Petition No.: NA 

Risk Assessment Type: NA 

TXR No.: NA 

M RID No.: NA 

Registration No.: NA 

Regulatory Action: NA 

Case No.: NA 

CAS No.: 51235-04-2 

40 CFR: NA 

Vcr.Apr.08 

FROM: Shanna Recore, Industrial Hygienist l 

1 0 

O 0 /'\, n . Toxicology 

Health ;:ects 

and 

D

Epidemiology 

ivision (7509P) 

Branch ~ (/!lj ~ 

~~Elizabeth Evans, Environmental Protection Special 

(v Toxicology and Epidemiology Branch 

Health Effects Division (7509P) {) u .1 ,· 9- 0 

'/'. ~v (} 

THROUGH: David J. Miller, Acting Branch Chi)· '1/1:) $t ~ ;{ cJjl 

Toxicology and Epidemiology Bran 

Health Effects Division (7509P) 

TO: Sheila Piper, Risk Assessor 

Risk Assessment Branch VI 

Health Effects Division (7509P) 

and 

Dana Friedman, Chemical Review Manager 

Risk Management & Implementation Branch 2 

Pesticide Re-evaluation Division (7508P) 

Summary and Conclusions 

Hexazinone was previously reviewed in 2009 (M. Hawkins and S. Recore, 11/24/2009, D372500). 

At the time, no hexazinone incidents were found in Main IDS for the single chemical hexazinone 

reviewing data from 2002 to 2009. For SENSOR-Pesticides, using data from 1998 to 2005, there 

were two cases reported involving hexazinone that were reviewed. These cases were low severity. 

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Upon review of these incidents, it was concluded that "Based on the low severity and low number 

of incident cases, there does not appear to be a risk concern at this time that would wan-ant further 

investigation." 

The cunent IDS analysis from January 1, 2010 through March 12, 2015, shows two incidents 

reported involving hexazinone in Main IDS and 21 incidents reported to Aggregate IDS. 

Further, a query of SENSOR-Pesticides 1998-201 I identifies a total of 13 cases involving 

hexazinone. Four of these cases involved the single active ingredient hexazinone. These 

incidents were classified as low severity. 

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

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

would wan-ant further investigation. The Agency will continue to monitor the incident 

information and if a concern is triggered, additional analysis will be conducted. 

The Agricultural Health Study (AHS) is also a potential source of information associated with 

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

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

Detailed Review 

I. ACTION REQUESTED 

Hexazinone are 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. 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. 

Rep01ts of adverse health effects all egedly 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 

confinned. 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 

Hexazinone is a triazine herbicide that acts through inhibition of photosynthesis. Hexazinone is 

registered for use on alfalfa, blueberries, pasture and range grasses, pineapples and sugarcane. It 

was first registered on November I 975 for general weed control in non-cropland areas. 

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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 hexazinone (PC Code: 107201 ). 

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

of the health effects attributed to hexazinone exposure. 

In addition, fi ndings from the Agricultural Health Study (AHS) were reviewed. The AHS is a 

high quality, prospective epidemiology study evaluating the link between pesticide use and 

various health outcomes including cancer. Hexazinone 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. 

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. 

From January 1, 2010 to March 12, 2015, there was one incidents repOited for the single 

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

involved a 36 yr old man, with history of seizures. He used Velpar ULW Herbicide for 3 to 4 

hours without PPE. Over the next week, he experienced an increased number and severity of 

seizures. There was one additional incidents reported involving more than one chemical. This 

incident was classified as minor severity. 

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From January 1, 2010 to March 12,2015, there were 21 incidents reported to Aggregate IDS 

involving hexazinone. Twelve of these incidents were classified as minor severity and nine of 

these incidents were classified as having no or unknown effects. 

b. SENSOR-Pesticides 

The SENSOR-Pesticides database covers 12 states from 1998-2011, 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 ofHealth. Although both occupational 

and non-occupational incidents are included in the database, SENSOR focuses on occupational 

pesticide incidents, and is of particular value in providing that information. A state SENSOR 

contact specialist attempts to follow-up with cases and obtains medical records to verify 

symptoms, circumstances surrounding the exposure, severity, and outcome. Using standardized 

protocol and case definitions derived from poison center reporting, SENSOR coordinators at 

State Departments of Health enter the incident interview description provided by the case, 

medical report, physician and patient into the SENSOR data system. The SENSOR data system 

is accessible to patticipating states and EPA. 

A query of SENSOR-Pesticides from 1998-2011 identifies a total of 13 cases involving 

hexazinone (pc code I 0720 I); four cases involve a single ai. All four of these cases were low in 

severity. Two cases experienced dennal symptoms including itchy skin and rash; two cases 

experienced oculat· symptoms including pain and conjunctivitis; and one case had upper 

respiratory pain. Three of the four were work-related. No case has been reported since 2003. 

The case circumstances vary widely; one case involved a water treatment plant operator, one was 

a farmer, one a forestry worker, and another case was a bystander. Descriptions for the latter two 

cases are provided: 

1. A forestry worker had been applying herbicides and developed health effects he thinks 

may be related. He reports similar upper respiratory symptoms each time he sprays. 

2. Case was standing in backyard when a truck spraying chemicals on the railroad passed by 

the fence and stat·ted spraying 

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. The AHS includes information on use of 50 different 

pesticide active ingredients commonly used in agriculture. Hexazinone 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 mostly low severity of incident cases reported for hexazinone in 

both IDS and NlOSH SENSOR-Pesticides, there does not appear to be a concern at this time that 

would warrant fU11her investigation. The Agency will continue to monitor the incident 

information and if a concern is triggered, additional analysis will be conducted. 

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