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Bromoxynil
CASRN 1689-84-5
Contents
0289
Bromoxynil; CASRN 1689-84-5
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 Bromoxynil
File On-Line 06/30/1988
Category (section) Status Last Revised
----------------------------------------- -------- ------------
Oral RfD Assessment (I.A.) on-line 06/30/1988
Inhalation RfC Assessment (I.B.) no data
Carcinogenicity Assessment (II.) no data
_I. CHRONIC HEALTH HAZARD ASSESSMENTS FOR NONCARCINOGENIC EFFECTS
__I.A. REFERENCE DOSE FOR CHRONIC ORAL EXPOSURE (RfD)
Substance Name -- Bromoxynil
CASRN -- 1689-84-5
Last Revised -- 06/30/1988
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
-------------------- ----------------------- ----- --- ---------
No adverse effects NOEL: 100 ppm (5 300 1 2E-2
mg/kg/day) mg/kg/day
2-Year Rat Feeding/
Oncogenic Study LEL: None
Union Carbide, 1982
*Conversion Factors: 1 ppm = 0.05 mg/kg/day (assumed rat food consumption)
___I.A.2. PRINCIPAL AND SUPPORTING STUDIES (ORAL RfD)
Union Carbide Agricultural Products Company, Inc. 1982. MRID No. 00096521.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Fischer-344 rats were randomly assigned to one of four treatment groups
(60/sex/group). The treatment groups consisted of animals receiving either 0,
10, 30, or 100 ppm of bromoxynil in their diet. All animals were observed
daily for mortality and external signs of toxicity. Blood and urine samples
were collected from 10 rats/sex/group after 3, 12, 18, and 24 months of dosing
for hematology determinations, urinalysis, and blood determinations. No
significant toxicological differences were noted between treated and control
groups.
___I.A.3. UNCERTAINTY AND MODIFYING FACTORS (ORAL RfD)
UF -- An uncertainty factor of 100 was used to account for the inter- and
intraspecies differences. An additional UF of 3 was used to account for an
insufficient data base, since the existing data base does not indicate that a
second mammalian chronic bioassay will be more sensitive by an order of
magnitude.
MF -- None
___I.A.4. ADDITIONAL COMMENTS (ORAL RfD)
Bromoxynil exists as an acid but also as esters (e.g., octanoate). Subchronic
studies indicate that there is no toxicological difference between these
different forms of bromoxynil; therefore, a common RfD considering data on all
forms of bromoxynil is appropriate.
Data Considered for Establishing the RfD:
1) 2-Year Feeding (oncogenic) - Principal study - see previous description;
core grade supplementary
2) 3-Generation Reproduction - rat: Reproduction NOEL=300 ppm (15 mg/kg/day)
(HDT); core grade minimum (Union Carbide, 1978)
3) Teratology - rat: Fetotoxic and Maternal NOEL=15 mg/kg/day; Fetotoxic and
Maternal LEL=35 mg/kg/day (reduced fetal weight; increased uterine deaths,
increased number of fetuses with supernumerary 14th rib, and reduced body
weight gain (maternal); core grade guideline (Union Carbide, 1981)
4) Teratology - rabbit: Teratogenic NOEL=30 mg/kg/day; Teratogenic LEL=60
mg/kg/day (hydrocephalus, microphthalmia, anopthalmia, and severe defects in
ossification of the skull); Maternal NOEL=15 mg/kg/day; Maternal LEL=30
mg/kg/day (body weight loss); Fetotoxic NOEL=30 mg/kg/day, Fetotoxic LEL=60
mg/kg/day lower body weight); core grade guideline (Rhone-Poulenc, 1983)
Data Gap(s): Chronic Dog Feeding Study (Note: A 13-week dog feeding study was
done using bromoxynil octanoate; the NOEL was 5 mg/kg/day.)
___I.A.5. CONFIDENCE IN THE ORAL RfD
Study -- Low
Data Base -- Medium
RfD -- Medium
The critical study appears to be only of fair quality and is given a low
rating. Additional studies are supportive and of fair to good quality. The
13-week dog feeding study (NOEL = 5 mg/kg/day), which utilized bromoxynil
octanoate, provides a sensitive toxicological endpoint that supports the 2-
year rat study. Therefore, the data base is given a medium rating. Medium
confidence in the RfD follows.
___I.A.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD
Source Document -- This assessment is not presented in any existing U.S. EPA
document.
Other EPA Documentation -- Pesticide Registration Files
Agency Work Group Review -- 05/31/1985, 08/05/1986, 09/16/1987
Verification Date -- 09/16/1987
___I.A.7. EPA CONTACTS (ORAL RfD)
Please contact the Risk Information Hotline for all questions concerning this
assessment or IRIS, in general, at (513)569-7254 (phone), (513)569-7159 (FAX)
or RIH.IRIS@EPAMAIL.EPA.GOV (internet address).
__I.B. REFERENCE CONCENTRATION FOR CHRONIC INHALATION EXPOSURE (RfC)
Substance Name -- Bromoxynil
CASRN -- 1689-84-5
Not available at this time.
_II. CARCINOGENICITY ASSESSMENT FOR LIFETIME EXPOSURE
Substance Name -- Bromoxynil
CASRN -- 1689-84-5
This substance/agent has not undergone a complete evaluation and determination
under US EPA's IRIS program for evidence of human carcinogenic potential.
_VI. BIBLIOGRAPHY
Substance Name -- Bromoxynil
CASRN -- 1689-84-5
Last Revised -- 11/01/1989
__VI.A. ORAL RfD REFERENCES
Union Carbide Agricultural Products Company, Inc. 1978. MRID No. 00064815.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Union Carbide Agricultural Products Company, Inc. 1981. MRID No. 00116558.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Union Carbide Agricultural Products Company, Inc. 1982. MRID No. 00096521.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Rhone-Poulenc, Inc. 1983. MRID No. 00138149. Available from EPA. Write to
FOI, EPA, Washington, DC 20460.
__VI.B. INHALATION RfD REFERENCES
None
__VI.C. CARCINOGENICITY ASSESSMENT REFERENCES
None
_VII. REVISION HISTORY
Substance Name -- Bromoxynil
CASRN -- 1689-84-5
-------- -------- --------------------------------------------------------
Date Section Description
-------- -------- --------------------------------------------------------
11/01/1989 VI. Bibliography on-line
01/01/1992 IV. Regulatory Action section on-line
VIII. SYNONYMS
Substance Name -- Bromoxynil
CASRN -- 1689-84-5
Last Revised -- 06/30/1988
1689-84-5
BENZONITRILE, 3,5-DIBROMO-4-HYDROXY-
BRITTOX
BROMINAL
BROMINEX
BROMINIL
Bromoxynil
BROXYNIL
BUCRIL
BUCTRIL
BUCTRIL INDUSTRIAL
BUTILCHLOROFOS
CHIPCO BUCTRIL
CHIPCO CRAB-KLEEN
2,6-DIBROMO-4-CYANOPHENOL
3,5-DIBROMO-4-HYDROXYBENZONITRILE
3,5-DIBROMO-4-HYDROXYPHENYLCYANIDE
ENT 20852
4-HYDROXY-3,5-DIBROMOBENZONITRILE
M B 10,064
M B 10731
MB 10064
ME4 BROMINAL
NU-LAWN WEEDER
OXYTRIL M
Last updated: 5 May 1998
URL: http://www.epa.gov/iris/SUBST/0289.HTM
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