UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

Date: 5/7/13 

MEMORANDUM 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Hexythiazox. Amended Registration to Allow Use on Cotton in Arizona. 

PC Code: 128849 DP Barcode: D4¢72.6.) 

Decision No.: 4'-YV'.?O Registration No.: 10163-277 

Petition No.: 2F8073 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. Davis, Risk Assessor ~~LV')__ Risk Assessment Branch VII 

Health Effects Division (7509 ~ 

THROUGH: Michael Metzger, Chief ~ 1 ~ !J (} L AI 

Risk Assessment Branch VII tti..tl-{ y( rv I 

Health Effects Division (7509 ) 

TO: Olga Odiott, Risk Manger 

Mark Suarez, Product Manager 

Meredith Laws, Chief 

Insecticide Branch 

Registration Division (7505P) 

Recommendations 

HED has no objection to the amendment of the Onager ® Miticide label to permit use of 

hexythiazox on cotton in the state of Arizona. This amendment will expand the current regional 

registration from California only to both California and Arizona. 

Tolerances are established under 40 CFR 180.448 (c) for residues ofhexythiazox on undelinted 

cotton seed and cotton gin byproducts. The tolerance expression and tolerance level established 

therein are adequate; however, the geographic limitation specified should be revised to include 

Arizona. 

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Background 

Gowan Company has petitioned (2F8073) the Agency to amend the hexythiazox registration to 

allow the use of the end use product, Onager® Miticide (EPA Reg No. 1 0 163-277) on cotton in 

the State of Arizona. Hexythiazox is currently registered for use on cotton only in California. 

The proposed use pattern in Arizona is identical to the current use pattern in California. 

Regionally restricted tolerances are established under 40 CFR 180.448 (c) for residues of 

hexythiazox on undelinted cotton seed at 0.2 ppm and cotton gin byproducts at 3 ppm for use in 

California only. No change in tolerance definition or tolerance level is proposed; the only 

change requested to the tolerance is to expand the regional registration from California only to 

California and Arizona. 

Residue Chemistry Considerations 

No new residue chemistry data were submitted with this petition. The registrant wishes to rely 

on previously submitted residue data which were reviewed and supported the regional 

registration of hexythiazox on cotton in California. The registrant notes that the only reason they 

did not seek regional registration in Arizona at the time that the California registration was 

requested was because hexythiazox was not registered in the State of Arizona at the time 

(personal communication via email from Kyla Smith, Gowan Company to Olga Odiott, EPA, 

7/5112). 

HED concurs that the residue data submitted to support the regional registration of hexythiazox 

on cotton in California is also adequate in terms of number and geographic representation to 

support the requested use in Arizona. No additional residue chemistry data are required to 

support the requested use expansion. 

Risk Assessment Considerations 

The risk assessment conducted to support the use of hexythiazox on cotton in California did not 

include consideration of the regional nature of the registration for cotton, but used tolerance level 

residues and assumed I 00% crop treated for cotton seed oil, the only human feed item associated 

with use on cotton. The assessment effectively assumed a national use; therefore this expansion 

to Arizona has no impact on the dietary risk assessment. 

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