UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MEMORANDUM 

Date: May 7, 2013 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

SUBJECT: TPTH (Triphenyltin Hydroxide). Response to Comments; Recommendation for 

Immunotoxicity Study Waiver 

PC Code: 083601 

Decision No.: 476725 

Petition No.: NA 

Risk Assessment Type: NA 

TXR No.: 0056654 

MRIDNo.:NA 

DP Barcode: 4l0327 

Registration No.: NA 

Regulatory Action: Registration Review 

Case No.: 99 

CAS No.: 76-87-9 

40 CFR: 180.236 

FROM: Mohsen Sahafeyan, Risk Assessor ,./~ ~c---:.:--z--__ 

Nancy McCarroll, Toxicologist ~C1Q.. ~¥-

Risk Assessment Branch VI (RAB VI) 

Health Effects Division (HED, 7509P) 

Office of Pesticide Programs 

THROUGH: Felecia Fort, Branch Chief 

RABVI;HED 

TO: Katherine St. Clair, Chemical Review Manager 

Risk Management & Implementation Branch IV 

Pesticide Re-evaluation Division (PRD) (7508P) 

Office ofPesticide Programs 

Conclusion: 

The HED concluded that the immunotoxicity study is not required for TPTH based on the 

HASPOC conclusion that the requirement for this study has been satisfied with consideration of 

submitted immunotoxicity studies in mice and rats, as well as the data available in the published 

literature. Additionally, although TPTH has shown evidence for immunotoxicity, the Points of 

Departures used for overall risk assessment will be protective of potential immunotoxicity from 

exposure of TPTH. 
Background: 

PRD notified HED of a conunent received from the Physicians Conunittee for Responsible 

Medicine (PCRM) during conunent period (letter dated 2/12/2013) for TPTH registration review 

docket. 

PCRM Comment: 

"Regarding the Immunotoxicity data request, we found four studies that may be useful in 

the risk assessment process. We encourage the Agency to waive the request for a new 

Immunotoxicity study for TPTH based on the data provided by these studies." 

The following studies were cited. 

• Vos, JG, Krajnc, E I. (1983). Develop Toxicol Environ Sci 11:229-240 at 

http:/ /toxnet.nlm.nih. gov · 

• World Health Organization/International Programme on Chemical Safety (1999). 

Concise International Chemical Assessment Document No. 13 Triphenyltin compounds. 

4-5 at http://toxnet.nlm.nih.gov 

• Sullivan, J B, Jr. Krieger, GR. (1992). Hazardous Materials Toxicology-Clinical 

Principles of Environmental Health at http://toxnet.nlm.nih.gov 

• Vos, J Get al. (1984). Effects oftriphenyltin hydroxide on the inunune system of the rat. 

Toxicology: 29-4 325-336 at http://www.unboubdmedicine.com 

HED Response: 

On April25, 2013 the Risk Assessment Branch (RAB) VI requested the Hazard and Science 

Policy Council (HASPOC) to discuss the need for an inununotoxicity study (Guideline series 

870.7800) to support the existing uses ofTPTH. 

In addition to the literature studies submitted by the PCRM, the HASPOC also considered two 

special TPTH inununotoxicity studies in rats and mice submitted to the Agency (MRID 

41518200). The HASPOC (TXR No.0056652) concluded that the requirement for 

inununotoxicity study has been satisfied based on the submitted immunotoxicity studies in mice 

and rats as well as the data available in the published literature. Additionally, although TPTH 

has shown evidence for inununotoxicity, the Points of Departures used for overall risk 

assessment will be protective of potential inununotoxicity from exposure to TPTH. 

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