UNITED STATES ENVIRONMENTAL PROTECTIO N AGE N CY WASHINGTON, D

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. 20460 O FFI C E OF CHEMICAL SAFETY AND POLLUT I ON PREVENTION

MEMORANDUM Date : Feb ru ary 5, 20 1 5 SUBJECT: Thidiaz uron: T ier I R evi ew of Human In cidents

P C C ode : 12030 1 Deci sio n No.: 4 989 47 Petition No . : NA Risk Assess m e nt Type: NA TXR No.: NA M RID No.: NA DP Barcode: 0425469 Reg i stra tio n No.: NA Regulatory Actio n: NA Case No.: NA CAS No.: 51707-55

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FROM: Shanna Recore, Industria l Hyg ie ni s t Toxicology and Epidemiology Branch Health Effect Di visio n (7509P) 

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/" Toxicology and Ep idemi ology Branch Ver.Apr.08

Heal th Effects Division (7509P) 

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### -U**5** THROUGH: David Miller, Acting Branch C hi e 1 '/jf/ Toxico logy and E pidemiolo gy Branch Health Effects Di v ision (7509P) TO: Ronnie Bever, Risk Assessor Ri sk Assessment Branch VII H ealth Effects D ivision (7509P) and Khue Nguye n , Chemical Rev iew Manager Risk Management & Imp lementation Branch I Pesticide Re-evaluation Di vi s ion (7508P) Summary and Co nclusions Based on the low frequency and low severity of in cident cases reported for thidiazuron in both IDS and SENSO R-Pesticides , there does not appear to be a concern at this time that wo uld warrant further investigation. The Agency will continue to monitor the incident information and if a concern i s tri ggered, additional analysis will be included in th e ri sk assessment.
Page I of 4Detailed 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 inc ident data. H owever, incident information can be an important source of feedback to the Agency: incidents of sever e outcome, or a suggested pattern or trend among less severe incidents , can signal the Agency to furthe r 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 T hidiazuron is used as a pre-harvest cotton defoliant or growth regulato r. It removes green leaves and immature fruiting structures, which contribute to cotton staining. There are no registered re sidential uses. 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

- Pest icides (SENSOR) databases were consu lte d for pesticide incident data on the active ingredient thidiazuron (pc code: 120301). The purpose of the database search is t o ident ify potential pattern s in the frequency and severity of the health effects attributed to thidiazuron exposure. Thidiazuron is not inc luded 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 t he U.S. and most incidents have all relevant product information recorded. Reports submitted to the IDS represent anecdotal report s or allegations only, unless otherwise stated in the report. IDS records incidents in one of two modules: Main IDS and Aggregate IDS:

Page 2 of4o Main I DS contains incide nts resu lting in higher severity outcomes and p rovides 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 mu ltiple active ingredients) are cons idered to provide more certain information about the pote nti al effects of expos ure from the p es ticide.

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. Fo r the Main IDS, fro m January 1 , 20 1 0 to December 30,201 4 , there we re 0 incidents reported involving thidiazuron

. In Aggregate IDS , from January 1, 2010 to December 30, 2014, there was 1 incident reported involving thidiazuron. This incident was classified as minor severity. Overall , there are few incidents involving thi diazuron reported to IDS. · 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 D epartments of Agricu lture, and phys ician reports to state Departments of Health. Althoug h both occupationa l 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 12 respective state Departments of Health conducts case fo ll owup activities such as obtaining medical records to verify symptoms and severity. Using standard ized protocol and case definitions derived from poison center reporting, the state SENSOR-Pestici de coordinator enters the incident information into th e state-based system which is sent to NIOSH annually to be aggregated. A review of SENSOR-Pesticides 1998-2011 identifies 16 cases involving thidiazuron (pc code 120301), one case involved a single ai. This case occurred in Texas in 1998 and was low in severity. The case is described in SENSOR as follows, "Complainant heard an aerial app lication occurr i ng nearby

. S h e went outside an d saw an aerial ap pli cator sprayi n g a cotton fiel d. "

c. Agricul tura l Health Stu dy (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 spo u ses. If there are AHS findings relevant to a partic ul ar pesticide going through registratio n rev iew, the Agen cy will ens u re they are considered in the problem formulation/scoping phase of the process and, if appropriate, fully reviewed in the risk assessment phase of the process. The AHS includes information on use of 80 different pesticide

Page 3 of4active ingredients commonly used in agriculture. Thidiazuron is not included in the AHS , and therefore this study does not provide information for this report. 

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