1,4-Dibromobenzene (CASRN 106-37-6)
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0148
1,4-Dibromobenzene;
CASRN 106-37-6
Health assessment information on a chemical substance is included in IRIS
only after a comprehensive review of chronic toxicity data by U.S. EPA
health scientists from several Program Offices and the Office of Research
and Development. The summaries presented in Sections I and II represent
a consensus reached in the review process. Background information and
explanations of the methods used to derive the values given in IRIS are
provided in the Background Documents.
STATUS OF DATA FOR 1,4-Dibromobenzene
File First On-Line 03/31/1987
Category (section) |
Status |
Last Revised |
---|---|---|
Oral RfD Assessment (I.A.) | on-line | 03/01/1988* |
Inhalation RfC Assessment (I.B.) | no data | |
Carcinogenicity Assessment (II.) | no data |
*A comprehensive review of toxicological studies was completed (2004) - please see section I.A.6 for more information.
_I. Chronic Health Hazard Assessments for Noncarcinogenic Effects
_I.A. Reference Dose for Chronic Oral Exposure (RfD)
Substance Name — 1,4-Dibromobenzene
CASRN — 106-37-6
Last Revised — 03/01/1988
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
|
---|---|---|---|---|
Liver/body weight Rat Subchronic Oral Carlson and Tardiff, |
NOAEL: 10 mg/kg/day LOAEL: 20 mg/kg/day |
1000
|
1
|
1E-2
mg/kg/day |
Conversion Factors: none
__I.A.2. Principal and Supporting Studies (Oral RfD)
Carlson, G.P. and R.G. Tardiff. 1977. Effect of 1,4-dibromobenzene and
1,2,4-tribromobenzene on xenobiotic metabolism. Toxicol. Appl. Pharmacol.
42: 189-196.
1,4-Dibromobenzene (DBB) was administered to adult male Sprague-Dawley rats
p.o. in corn oil. Groups of six rats were given 0, 5, 10, or 20 mg DBB/kg for
45 or 90 days. Rats were sacrificed 24 hours or 30 days after the last dose.
No overt signs of toxicity were observed. The parameters measured were body
weight gain, liver-to-body weight ratio, liver histopathology and hepatic
microsomal enzyme activity. No gross or microscopic hepatic lesions were
found. Liver-to-body weight ratio and liver enzyme activity were both
significantly increased at 20 mg/kg after 45 and 90 days. Both parameters
were normal in the animals sacrificed 30 days later. A statistically
significant increase in the activity of 1 of 6 microsomal enzymes was found at
10 mg/kg/day, but was not accompanied by an increase in liver-to-body weight
ratio.
Increases in both liver-to-body weight ratio and hepatic microsomal enzyme
activity are appropriately considered as adverse effects, since high-dose
acute effects of DBB include liver damage, probably due to the formation of a
toxic metabolite. The formation of this metabolite is enhanced by induction
of liver enzymes.
__I.A.3. Uncertainty and Modifying Factors (Oral RfD)
UF — An uncertainty factor of 10, in addition to the usual 100 that accounts
for inter- and intraspecies differences, is necessary to allow for the
uncertainty in subchronic-to-chronic dose extrapolation.
MF — None
__I.A.4. Additional Studies/Comments (Oral RfD)
None.
__I.A.5. Confidence in the Oral RfD
Study — Medium
Database — Low
RfD — Low
The study is well-designed and clearly reported, but of short duration with a limited number of animals. The desired range of toxicity parameters is missing, since the study was designed primarily to investigate liver enzyme induction. Medium confidence is assigned. Additional studies pertaining to subchronic or chronic toxicity were not found. However, a great deal of information is available on the metabolism and mechanism of toxicity of brominated benzenes which qualitatively supports this risk assessment. Thus, the database rates low confidence. Low confidence in the RfD follows.
__I.A.6. EPA Documentation and Review of the Oral RfD
Source Document — U.S. EPA, 1984
The Health and Environmental Effects Profile for Bromobenzenes received an
Agency Review with the help of two outside scientists.
Other EPA Documentation — None
Agency Work Group Review — 10/09/1985, 05/15/1986
Verification Date — 05/15/1986
A comprehensive review of toxicological studies published prior to 2004 was conducted. No new health effects data were identified that would be directly useful in the revision of the existing RfD for 1,4-Dibromobenzene and a change in the RfD is not warranted at this time.
__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).
_I.B. Reference Concentration for Chronic Inhalation Exposure (RfC)
Substance Name — 1,4-Dibromobenzene
CASRN — 106-37-6
Not available at this time.
_II. Carcinogenicity Assessment for Lifetime Exposure
Substance Name — 1,4-Dibromobenzene
CASRN — 106-37-6
This substance/agent has not undergone a complete evaluation and determination under US EPA's IRIS program for evidence of human carcinogenic potential.
_III.
[reserved]
_IV. [reserved]
_V. [reserved]
_VI. Bibliography
Substance Name — 1,4-Dibromobenzene
CASRN — 106-37-6
Last Revised — 08/01/1989
_VI.A. Oral RfD References
Carlson, G.P. and R.G. Tardiff. 1977. Effect of 1,4-dibromobenzene and
1,2,4-tribromobenzene on xenobiotic metabolism. Toxicol. Appl. Pharmacol.
42: 189-196.
U.S. EPA. 1984. Health and Environmental Effects Profile for Bromoben-
zenes. Prepared by the Office of Health and Environmental Assessment,
Environmental Criteria and Assessment Office, Cincinnati, OH for the Office of
Solid Waste, Washington, DC.
_VI.B. Inhalation RfC References
None
_VI.C. Carcinogenicity Assessment References
None
_VII. Revision History
Substance Name — 1,4-Dibromobenzene
CASRN — 106-37-6
Date |
Section |
Description |
---|---|---|
03/01/1988 | I.A.2. | Text clarified |
08/01/1989 | VI. | Bibliography 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. |
10/28/2003 | I.A.6. | Screening-Level Literature Review Findings message has been added. |
09/29/2004 | I.A.6. | Screening-Level Literature Review Findings message has been removed and replaced by comprehensive literature review conclusions. |
_VIII. Synonyms
Substance Name — 1,4-Dibromobenzene
CASRN — 106-37-6
Last Revised — 03/31/1987
- 106-37-6
- BENZENE, 1,4-DIBROMO-
- BENZENE, p-DIBROMO-
- p-BROMOPHENYL BROMIDE
- 1,4-Dibromobenzene
- Dibromobenzene, 1,4-
- p-DIBROMOBENZENE