UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

Date: 1130/13 

MEMORANDUM 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Hexythiazox. Registration Review Preliminary Risk Assessment. 

PC Code: 128849 DP Barcode: D406658 

Decision No.: 471595 Registration No.: 10163-277 

Petition No.: NA Regulatory Action: Registration Review 

Risk Assessment Type: Single Chemical Case No.: 7404-1 Aggregate 

TXRNo.: NA CAS No.: 78587-05-0 

MRIDNo.: NA 40 CFR: 40 CFR 180.448 

FROM: DonnaS. 

Alexandra 

Davis, 

LaMay, 

Risk 

Biolo

Assesso st~~~ ~ ~ 

_ / C 

Linda Taylor, Toxicologist ~ ~~ c 

Risk Assessment Branch VI 

Health Effects Division (7509P) 

THROUGH: Michael Metzger, Chief ': j J / /!L----

Risk Assessment Branch VI /vf' t /1, If 

Health Effects Division (7509 ) 

TO: Molly Clayton, Risk Manager 

Tracy Perry, Team Leader 

Patricia Parrott, Chief 

Risk Management and Implementation Branch III 

Pesticide Re-Evaluation Division (7508P) 

Page 1 of2 
Hexythiazox Registration Review Preliminary Risk Assessment 

Hexythiazox is an insecticide currently registered on a wide array of agricultural crops as well as 

in residential settings including ornamental plantings, turf, and residential fruit and nut trees. 

Dietary, residential, and aggregate risks for hexythiazox were addressed in the HED 

memorandum entitled "Hexythiazox. Human Health Risk Assessment to Support New Uses on 

Alfalfa and Timothy" (D396526, D404477, 9/25/12, D. Davis). Since this recently conducted 

risk assessment addressed all dietary, residential, and aggregate exposures associated with the 

registered uses of hexythiazox, considered all available hazard and exposure data submitted to 

the Agency, included updated points of departure and safety/uncertainty factors, and used current 

HED policies and procedures, it constitutes the dietary, residential and aggregate human health 

preliminary risk assessment for registration review. There are no dietary, residential or 

aggregate risks of concern for the registered uses of hexythiazox. 

The occupational risks associated with the use ofhexythiazox on alfalfa, timothy, field corn, and 

tomatoes were recently assessed in the HED memoranda entitled "Hexythiazox. Human Health 

Risk Assessment to Support New Uses on Alfalfa and Timothy" (0396526, D404477, 9/25112, 

D. Davis) and "Hexythiazox. Human Health Risk Assessment to Support Amended Use on Field 

Corn and New Use on Greenhouse Tomatoes" (D383744, 6/22/11, D. Davis). Occupational 

scenarios not assessed in these memoranda were screened in the HED memorandum 

"Hexythiazox: Summary of Hazard and Science Policy Council (HASPOC) Meetings: 

Recommendations on the need for the inhalation, and acute and subchronic neurotoxicity 

studies" (TXR # 0056434, 10/18/12, K. Rury). Since the recently conducted occupational risk 

assessments and HASPOC screen cited above address all registered uses of hexythiazox, 

considered all available hazard and exposure data submitted to the Agency, included updated 

points of departure and safety/uncertainty factors, and used current HED policies and procedures, 

when considered together they constitute the occupational preliminary risk for registration 

review. There are no occupational risks of concern for the registered uses of hexythiazox. 

Page 2 of2