Bromoxynil (CASRN 1689-84-5) | IRIS
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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 First 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 2-Year Rat Feeding/ Union Carbide, 1982 |
NOEL: 100 ppm (5 LEL: None |
300
|
1
|
2E-2
mg/kg/day |
*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 database does not indicate that a second mammalian chronic bioassay 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; 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
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 (NOEL = 5 mg/kg/day), which utilized bromoxynil octanoate, provides a sensitive toxicological endpoint that supports the 2- year rat study. Therefore, the database 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 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
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.
_III.
[reserved]
_IV. [reserved]
_V. [reserved]
_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 |
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. |
02/22/2001 | I.A., II. | This chemical is being reassessed under the IRIS Program. |
02/09/2004 | I.A., II. | This chemical is no longer being reassessed under the IRIS Program. See Federal Register February 9, 2004 (Volume 69, Number 26). |
_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