1

MEMORANDUM

TO: Sandra Gaona

Acting Chief Analytical Support Branch

CC: Daniel Bushman , Ph.D.

Analytical Support Branch

FROM: Jocelyn Hospital

Toxicologist Analytical Support Branch

DATE: November 3, 2014

SUBJECT: Review of National Toxicology Program (NTP) Cancer Classification Data for 1

-

bromopropane

The NTP Report on Carcinogens, Thirteenth Edition (RoC) (NTP, 2014) identified 1

- bromopropane as “ reasonabl y anticipated to be a human carcinogen

. ” The NTP RoC Substance P rofile for 1

- bromopropane (NTP, 2014 )

, the NTP RoC M onograph for 1

- bromopropane (NTP, 2013 )

, the primary NTP study of 1

- bromopropane (NTP, 2011)

, and other supporting documents cited in the NTP RoC Substance Profile have been reviewed

.

Consistent with the EPA G uidelines for Carcinogen Risk Assessment, the NTP RoC evaluates the scientific literature and publicly available , p eer

- reviewed technical reports of human and laboratory studies to evaluate whether substances are possible human carcinogens. T he NTP RoC does not present a quantitative assessment of the risks of cancer associated with a given chemical. Rather, they indicate the potential hazard associated with chemicals but do not establish the exposure conditions that would pose cancer risks to individual s.

Inconsistencies between how the data were interpreted by the NTP and how that same data might be interpreted under EPA’s Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005) were not identified. The EPA C ancer G uidelines reference the NTP criteria for assessing individual stud ies in the assessment of carcinogenicity, stating “(c) riteria for the technical adequacy of animal carcinogenicity studies have been published and should be used as guidance to judge the accep tability of indiv idual studies, e.g., NTP, 1984 ...” (pg. 2

- 16).

NTP and EPA use similar criteria for listing chemicals as “reasonably anticipated to be a human carcinogen” or “likely to be carcinogenic to humans” , respectively. The EPA Guidelines for Carcinogen Risk Assessm ent (U.S. EPA, 2005) specifically detail “likely to be carcinogenic to humans” as a comparable weight of evidence term to the NTP classification “reasonably anticipated to be a human carcinogen” (pg. 2

- 53). Supporting data for an agent listed with this EPA descriptor includes “an agent that has tested positive in animal experiments in more than one species, sex, strain, site, or exposure route, with or without evidence of carcinogenicity in2

humans”. Based on the available data , the NTP RoC Monograph and Sub stance Profile have identified 1

- bromopropane as “ reasonably anticipated to be a human carcinogen

, ” as an increased incidence of tumors was observed in experimental animals at multiple sites in multiple species.

The conclusions of the NTP RoC for 1

- bromopropane were consistent with how the Agency would consider the carcinogenicity data available for 1

- bromopropane

. Therefore, it would be appropriate for the Agency, for the purposes of listing 1

- bromopropane on the Toxics Release Inventory, to conclude that 1

- bromopropane can reasonabl y be anticipated to cause cancer in humans

.

References

National Toxicology Program (NTP)

. ( 2011 )

. Technical Report on the Toxicology and Carcinogenesis Studies of 1

- Bromopropane (C AS No. 106

- 94

- 5) in F344/N Rats and B6C3F1 Mice (Inhalation Studies)

. Toxicity Report Series No. 564. NIH Publication No. 11

- 59 06. Department of Health and Human Services, Public Health Service

, Research Triangle Park, NC.

NTP. ( 2013 ). Report on Carcinogens Monograph on 1

- bromopropane

. Department of Health and Human Services, Public Health Service, Research Triangle Park, NC

.
NTP. ( 2014 ). Report on Carcinogens

, Thirteenth Edition

. Department of Health and Human Services, Public Healt h Service, Research Triangle Park, NC

. U.S. EPA. (2005) Guidelines for carcinogen risk assessment. Risk Assessment Forum, Washington, DC; EPA/630/P

- 03/001F.