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Pentabromodiphenyl ether (CASRN 32534-81-9)

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0184

Pentabromodiphenyl ether; CASRN 32534-81-9


Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data, as outlined in the IRIS assessment development process. Sections I (Health Hazard Assessments for Noncarcinogenic Effects) and II (Carcinogenicity Assessment for Lifetime Exposure) present the conclusions that were reached during the assessment development process. Supporting information and explanations of the methods used to derive the values given in IRIS are provided in the guidance documents located on the IRIS website.

STATUS OF DATA FOR Pentabromodiphenyl ether

File First On-Line 03/31/1987

Category (section)
Status
Last Revised
Oral RfD Assessment (I.A.) on-line 08/01/1990
Inhalation RfC Assessment (I.B.) no data  
Carcinogenicity Assessment (II.) on-line 08/01/1990

_I.  Chronic Health Hazard Assessments for Noncarcinogenic Effects

_I.A. Reference Dose for Chronic Oral Exposure (RfD)

Substance Name — Pentabromodiphenyl ether
CASRN — 32534-81-9
Last Revised — 08/01/1990

The oral Reference Dose (RfD) is based on the assumption that thresholds exist for certain toxic effects such as cellular necrosis. It is expressed in units of mg/kg-day. In general, the RfD is an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. Please refer to the Background Document for an elaboration of these concepts. RfDs can also be derived for the noncarcinogenic health effects of substances that are also carcinogens. Therefore, it is essential to refer to other sources of information concerning the carcinogenicity of this substance. If the U.S. EPA has evaluated this substance for potential human carcinogenicity, a summary of that evaluation will be contained in Section II of this file.

__I.A.1. Oral RfD Summary

Critical Effect
Experimental Doses*
UF
MF
RfD

Induction of hepatic
enzymes

Subchronic, Rat, Oral
(gavage)

Carlson, 1980

NOAEL: 3.13 umol/kg/
day (1.77 mg/kg/day)

LOAEL: 6.25 umol/
kg/day (3.52 mg/kgday

1000
1
2E-3
mg/kg/day

*Conversion Factors: 1 umol = 0.5647 mg

__I.A.2. Principal and Supporting Studies (Oral RfD)

Carlson, G.P. 1980. Induction of xenobiotic metabolism in rats by brominated diphenyl ethers administered for 90 days. Toxicol. Lett. 6: 207-212.

Carlson (1980) administered pentabromodiphenyl ether (commercial grade) in corn oil by gavage to groups of six male Sprague-Dawley rats weighing 200 to 250 g for 90 days. Two dosing regimens were used: a high-dose series of 0, 6.25, 12.5, or 25 umol/kg/day (equivalent to 0, 3.53, 7.06, or 14.12 mg/kg/day, respectively) and a low-dose series of 0, 0.78, 1.56, or 3.13 umol/kg/day (equivalent to 0, 0.44, 0.88, or 1.77 mg/kg/day, respectively). Liver enzyme induction occurred at all dose levels, and some of these changes were persistent, lasting for 30-60 days after the cessation of treatment. No histologic liver abnormalities were observed in rats administered the low-dose series. Histologic evaluation was not performed on the high-dose rats; thus, these dose levels should be considered as possible AELs (adverse-effect levels). Since the relevance of hepatic enzyme induction to health effects is not established, this endpoint, in the absence of a histopathology evaluation, is not considered adverse. Thus, the highest NOAEL for pentabromodiphenyl ether is considered to be 1.77 mg/kg/day, the highest dose for which liver enzyme induction occurred, but no histologic liver abnormalities were found.

__I.A.3. Uncertainty and Modifying Factors (Oral RfD)

UF — The uncertainty of 1000 reflects 10 for both intraspecies and interspecies variability to the toxicity of this chemical in lieu of specific data, and 10 for extrapolation of a subchronic effect level to its chronic equivalent.

MF — None

__I.A.4. Additional Studies/Comments (Oral RfD)

None.

__I.A.5. Confidence in the Oral RfD

Study — Low
Database — Low
RfD — Low

Although six dose levels were used in the critical study, the study was of short duration, only one sex and one species were exposed, there were only six animals/group, and few toxic endpoints were examined. The study also did not establish a definitive LOAEL or NOAEL; thus, confidence in the study is low. Supporting evidence is limited; therefore, a low confidence rating is given to the database. Low confidence in the RfD follows.

__I.A.6. EPA Documentation and Review of the Oral RfD

Source Document — U.S. EPA, 1983

This document has received an Agency Review with the help of two external scientists.

Other EPA Documentation — None

Agency Work Group Review — 10/09/1985, 05/15/1986

Verification Date — 05/15/1986

Screening-Level Literature Review Findings — A screening-level review conducted by an EPA contractor of the more recent toxicology literature pertinent to the RfD for Pentabromodiphenyl ether conducted in September 2002 did not identify any critical new studies. IRIS users who know of important new studies may provide that information to the IRIS Hotline at hotline.iris@epa.gov or (202)566-1676.

__I.A.7. EPA Contacts (Oral RfD)

Please contact the IRIS Hotline for all questions concerning this assessment or IRIS, in general, at (202)566-1676 (phone), (202)566-1749 (FAX) or hotline.iris@epa.gov (internet address).

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_I.B. Reference Concentration for Chronic Inhalation Exposure (RfC)

Substance Name — Pentabromodiphenyl ether
CASRN — 32534-81-9

Not available at this time.

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_II.  Carcinogenicity Assessment for Lifetime Exposure

Substance Name — Pentabromodiphenyl ether
CASRN — 32534-81-9
Last Revised — 08/01/1990

Section II provides information on three aspects of the carcinogenic assessment for the substance in question; the weight-of-evidence judgment of the likelihood that the substance is a human carcinogen, and quantitative estimates of risk from oral exposure and from inhalation exposure. The quantitative risk estimates are presented in three ways. The slope factor is the result of application of a low-dose extrapolation procedure and is presented as the risk per (mg/kg)/day. The unit risk is the quantitative estimate in terms of either risk per ug/L drinking water or risk per ug/cu.m air breathed. The third form in which risk is presented is a drinking water or air concentration providing cancer risks of 1 in 10,000, 1 in 100,000 or 1 in 1,000,000. The rationale and methods used to develop the carcinogenicity information in IRIS are described in The Risk Assessment Guidelines of 1986 (EPA/600/8-87/045) and in the IRIS Background Document. IRIS summaries developed since the publication of EPA's more recent Proposed Guidelines for Carcinogen Risk Assessment also utilize those Guidelines where indicated (Federal Register 61(79):17960-18011, April 23, 1996). Users are referred to Section I of this IRIS file for information on long-term toxic effects other than carcinogenicity.

_II.A. Evidence for Human Carcinogenicity

__II.A.1. Weight-of-Evidence Characterization

Classification — D; not classifiable as to human carcinogenicity

Basis — No human data and animal data available.

__II.A.2. Human Carcinogenicity Data

None.

__II.A.3. Animal Carcinogenicity Data

None.

__II.A.4. Supporting Data for Carcinogenicity

Pentabromodiphenyl ether (purity unknown) was not mutagenic in a Salmonella typhimurium assay, in which four strains were utilized both with and without metabolic activation (Zeiger et al., 1987).

Pentabromodiphenyl ether is structurally-related to decabromodiphenyl ether, a possible human carcinogen. Decabromodiphenyl ether is also not mutagenic for S. typhimurium.

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_II.B. Quantitative Estimate of Carcinogenic Risk from Oral Exposure

None.

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_II.C. Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

None.

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_II.D. EPA Documentation, Review, and Contacts (Carcinogenicity Assessment)

__II.D.1. EPA Documentation

Source Document — U.S. EPA, 1984 . Health and Environmental Effects Profile for Brominated Diphenyl Ethers. Prepared by the Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH for the Office of Solid Waste and Emergency Response, Washington, DC.

The 1984 Health and Environmental Effects Profile for Brominated Diphenyl Ethers has received Agency Review.

__II.D.2. EPA Review (Carcinogenicity Assessment)

Agency Work Group Review — 06/15/1990

Verification Date — 06/15/1990

Screening-Level Literature Review Findings — A screening-level review conducted by an EPA contractor of the more recent toxicology literature pertinent to the cancer assessment for Pentabromodiphenyl ether conducted in September 2002 did not identify any critical new studies. IRIS users who know of important new studies may provide that information to the IRIS Hotline at hotline.iris@epa.gov or (202)566-1676.

__II.D.3. EPA Contacts (Carcinogenicity Assessment)

Please contact the IRIS Hotline for all questions concerning this assessment or IRIS, in general, at (202)566-1676 (phone), (202)566-1749 (FAX) or hotline.iris@epa.gov (internet address).

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_III.  [reserved]
_IV.  [reserved]
_V.  [reserved]


_VI.  Bibliography

Substance Name — Pentabromodiphenyl ether
CASRN — 32534-81-9
Last Revised — 08/01/1990

_VI.A. Oral RfD References

Carlson, G.P. 1980. Induction of xenobiotic metabolism in rats by bromi- nated diphenyl ethers administered for 90 days. Toxicol. Lett. 6: 207-212.

U.S. EPA. 1983. Health and Environmental Effects Profile for Brominated Diphenyl Ethers. Prepared by the Office of Health and Environmental Assess- ment, Environmental Criteria and Assessment Office, Cincinnati, OH for the Office of Solid Waste, Washington, DC.

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_VI.B. Inhalation RfC References

None

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_VI.C. Carcinogenicity Assessment References

U.S. EPA. 1984. Health and Environmental Effects Profile for Brominated Diphenyl Ethers. Prepared by the Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH for the Office of Solid Waste and Emergency Response, Washington, DC.

Zeiger, E., B. Anderson, S. Haworth, T. Lawlor, K. Mortelmans and W. Speck. 1987. Salmonella mutagenicity tests: III. Results from the testing of 255 chemicals. Environ. Mutag. 9(Suppl. (9): 1-110.

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_VII.  Revision History

Substance Name — Pentabromodiphenyl ether
CASRN — 32534-81-9

Date
Section
Description
09/01/1989 VI. Bibliography on-line
07/01/1990 II. Carcinogen assessment now under review
08/01/1990 I.A. Text edited
08/01/1990 II. Carcinogen assessment on-line
08/01/1990 VI.C. Carcinogen references added
01/01/1992 I.A.7. Secondary contact changed
01/01/1992 IV. Regulatory Action section on-line
04/01/1997 III., IV., V. Drinking Water Health Advisories, EPA Regulatory Actions, and Supplementary Data were removed from IRIS on or before April 1997. IRIS users were directed to the appropriate EPA Program Offices for this information.
12/03/2002 I.A.6., II.D.2. Screening-Level Literature Review Findings message has been added.
02/05/2003 I., II. This chemical is being reassessed under the IRIS Program.
12/07/2004 I.A.2. Text corrected.

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_VIII.  Synonyms

Substance Name — Pentabromodiphenyl ether
CASRN — 32534-81-9
Last Revised — 03/31/1987

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