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Bromoxynil octanoate
CASRN 1689-99-2
Contents
0138
Bromoxynil octanoate; CASRN 1689-99-2
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 octanoate
File On-Line 03/31/1987
Category (section) Status Last Revised
----------------------------------------- -------- ------------
Oral RfD Assessment (I.A.) on-line 09/07/1988
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 octanoate
CASRN -- 1689-99-2
Last Revised -- 09/07/1988
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 effects NOEL: 100 ppm bromoxynil 300 1 2E-2
(7.3 mg/kg/day bromoxynil mg/kg/day
2-Year Rat Feeding octanoate)
Study
LEL: None
Union Carbide, 1982
*Conversion Factors: 1 ppm = 0.05 mg/kg/day (assumed rat food consumption);
dose adjusted by the ratio of the molecular weights of bromoxynil octanoate
(402.8) and bromoxynil (276.8).
___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 the
dog (chronic exposure) 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. The RfDs for all bromoxynil compounds will be
based on the toxicity of bromoxynil alone, unless evidence to the contrary is
found.
Data Considered for Establishing the RfD:
1) 2-Year Feeding (oncogenic) (bromoxynil) - rat: prinicipal study - see
previous description; core grade supplementary
2) 13-Week Feeding (bromoxynil octanoate) - dog: NOEL = 5 mg/kg/day (Rhone-
Poulenc, 1965)
3) 3-Generation Reproduction (bromoxynil) - rat: Reproduction NOEL=300 ppm
(15 mg/kg/day); LEL=none (HDT); core grade minimum (Union Carbide, 1978)
4) Teratology (bromoxynil) - 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 maternal body weight gain; core grade guideline (Union Carbide, 1981)
5) Teratology (bromoxynil) - 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=30 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
___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 provides a sensitive toxicological endpoint that
supports the 2-year rat study. Hence, the RfD is given a medium confidence
rating.
___I.A.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD
Pesticide Registration Files
Agency Work Group Review -- 11/06/1985, 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 octanoate
CASRN -- 1689-99-2
Not available at this time.
_II. CARCINOGENICITY ASSESSMENT FOR LIFETIME EXPOSURE
Substance Name -- Bromoxynil octanoate
CASRN -- 1689-99-2
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 octanoate
CASRN -- 1689-99-2
Last Revised -- 11/01/1989
__VI.A. ORAL RfD REFERENCES
Rhone-Poulenc, Inc. 1965. MRID No. 00111190. 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.
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.
__VI.B. INHALATION RfD REFERENCES
None
__VI.C. CARCINOGENICITY ASSESSMENT REFERENCES
None
_VII. REVISION HISTORY
Substance Name -- Bromoxynil octanoate
CASRN -- 1689-99-2
-------- -------- --------------------------------------------------------
Date Section Description
-------- -------- --------------------------------------------------------
12/23/1987 I.A. Rfd Withdrawn pending further review
09/07/1988 I.A. Oral RfD summary on-line
11/01/1989 VI. Bibliography on-line
01/01/1992 IV. Regulatory Action section on-line
VIII. SYNONYMS
Substance Name -- Bromoxynil octanoate
CASRN -- 1689-99-2
Last Revised -- 03/31/1987
1689-99-2
BENZONITRILE, 3,5-DIBROMO-4-OCTANOYLOXY-
Bromoxynil octanoate
BRONATE
BUCTRIL
2,6-DIBROMO-4-CYANOPHENYL OCTANOATE
3,5-DIBROMO-4-OCTANOYLOXY-BENZONITRILE
M B 10731
RP-16272
Last updated: 5 May 1998
URL: http://www.epa.gov/iris/SUBST/0138.HTM
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