Bromoxynil octanoate (CASRN 1689-99-2)
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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 First 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 2-Year Rat Feeding Union Carbide, 1982 |
NOEL: 100 ppm bromoxynil LEL: None |
300
|
1
|
2E-2
mg/kg/day |
*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 database since the existing database does not indicate that the
dog (chronic exposure) will be more sensitive by an order of magnitude.
MF — None
__I.A.4. Additional Studies/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
Database — 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
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 Bromoxynil octanoate conducted in September 2002 identified one or more significant new studies. IRIS users may request the references for those studies from 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).
_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.
_III.
[reserved]
_IV. [reserved]
_V. [reserved]
_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 RfC 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 |
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. | Screening-Level Literature Review Findings message has been added. |
_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