Dicamba (CASRN 1918-00-9)
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0223
Dicamba;
CASRN 1918-00-9
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 Dicamba
File First On-Line 09/30/1987
Category (section) |
Status |
Last Revised |
---|---|---|
Oral RfD Assessment (I.A.) | on-line | 07/01/1992 |
Inhalation RfC Assessment (I.B.) | no data | |
Carcinogenicity Assessment (II.) | no data | 11/01/1993 |
_I. Chronic Health Hazard Assessments for Noncarcinogenic Effects
_I.A. Reference Dose for Chronic Oral Exposure (RfD)
Substance Name — Dicamba
CASRN — 1918-00-9
Primary Synonym — Banvel
Last Revised — 07/01/1992
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 |
---|---|---|---|---|
Maternal and fetal Rabbit Developmental Velsicol Chemical, 1978 |
NOEL: 3 mg/kg/day LEL: 10 mg/kg/day |
100
|
1
|
3E-2
mg/kg/day |
*Conversion Factors: none
__I.A.2. Principal and Supporting Studies (Oral RfD)
Velsicol Chemical Corporation. 1978. MRID No. 00028236. Available from EPA.
Write to FOI, EPA, Washington, DC 20460.
Five groups of female rabbits (31 to 35/group) were dosed with 0.5% methyl
cellulose at 1 mg/kg/day containing doses of 0, 1.0, 3.0, or 10.0 mg/kg/day of
dicamba (Banvel technical). A positive control group was treated with 3
mg/kg/day of 6-aminonicotinamide on day 9 of gestation only. Dicamba was
administered on days 6 through 18 of gestation. Because of an insufficient
number of pregnancies in the initial phases of the experiment, additional
rabbits were added to each group at a later starting time. Rabbits receiving
10 mg/kg/day (HDT) had a slightly lower net weight gain. Also, there were
slightly reduced fetal body weights and increased post implantation loss in
the 10 mg/kg/day group. A NOEL was observed for maternal and fetotoxicity at
3 mg/kg/day.
__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.
MF — None
__I.A.4. Additional Studies/Comments (Oral RfD)
Data Considered for Establishing the RfD
1) Developmental - rabbit: Principal study - see previous description; core
grade minimum
2) 1-Year Feeding - dog: NOEL=2500 ppm (52 mg/kg/day) (HDT); core grade
minimum (Sandoz Crop Protection, 1986)
3) 2-Year Feeding (oncogenic) - rat: Systemic NOEL=2500 ppm (125 mg/kg/day);
LEL=none; core grade minimum (Velsicol Chemical, 1985)
4) 3-Generation Reproduction - rat: NOEL=500 ppm (25 mg/kg/day) (HDT);
LEL=none; core grade minimum (Velsicol Chemical, 1966)
5) Developmental - rat: Maternal NOEL=160 mg/kg/day; Maternal LEL=400
mg/kg/day (ataxia, salivation, decreased motor activity, mortality, decreased
body weight); Fetotoxic NOEL=400 mg/kg/day (HDT); Fetotoxic LEL=none; core
grade minimum; Teratogenic NOEL=requires clarification because of the
occurrence of skeletal malformations at all dosage levels, which are not
statistically significant (Velsicol Chemical, 1981a)
Other Data Reviewed:
1) 2-Year Feeding - dog: NOEL=5 ppm (0.125 mg/kg/day); LEL=25 ppm (0.625
mg/kg/day) (decrease in body weight); core grade supplementary (No
observations of pharmacologic effects were presented, no gross pathology was
done, there was no clinical chemistry data and scant histopathology presented)
(Velsicol Chemical, 1962a)
2) 2-Year Feeding (oncogenic) - rat: Systemic NOEL=500 ppm (25 mg/kg/day)
(HDT); core grade supplementary (Velsicol Chemical, 1962b)
3) 90-Day Feeding - rat: NOEL=5000 ppm (250 mg/kg/day); LEL=10,000 ppm (500
mg/kg/day) (slight decrease in body weight and food consumption; reduction of
cytoplasmic vacuolation of hepatocytes); core grade minimum (Velsicol
Chemical, 1981b)
Data Gap(s): None
__I.A.5. Confidence in the Oral RfD
Study — Medium
Database — High
RfD — High
The critical study is of adequate quality and is given a medium confidence rating. Additional studies are supportive and therefore the database is given a high confidence rating. High 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 — 05/30/1986, 02/18/1987, 06/22/1988
Verification Date — 06/22/1988
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 Dicamba 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 — Dicamba
CASRN — 1918-00-9
Primary Synonym — Banvel
Not available at this time.
_II. Carcinogenicity Assessment for Lifetime Exposure
Substance Name — Dicamba
CASRN — 1918-00-9
Primary Synonym — Banvel
Not available at this time.
_III.
[reserved]
_IV. [reserved]
_V. [reserved]
_VI. Bibliography
Substance Name — Dicamba
CASRN — 1918-00-9
Primary Synonym — Banvel
Last Revised — 07/01/1992
_VI.A. Oral RfD References
Sandoz Crop Protection Corporation. 1986. MRID No. 40321102. Available from
EPA. Write to FOI, EPA, Washington, DC 20460.
Velsicol Chemical Corporation. 1962a. MRID No. 00028248, 00028260, 00050492.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Velsicol Chemical Corporation. 1962b. MRID No. 00028248, 00028260.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Velsicol Chemical Corporation. 1966. MRID No. 00028249. Available from
EPA. Write to FOI, EPA, Washington, DC 20460.
Velsicol Chemical Corporation. 1978. MRID No. 00028236. Available from
EPA. Write to FOI, EPA, Washington, DC 20460.
Velsicol Chemical Corporation. 1981b. MRID No. 00128093. Available from
EPA. Write to FOI, EPA, Washington, DC 20460.
Velsicol Chemical Corporation. 1981a. MRID No. 00084024. Available from
EPA. Write to FOI, EPA, Washington, DC 20460.
Velsicol Chemical Corporation. 1985. MRID No. 00125333. 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 — Dicamba
CASRN — 1918-00-9
Primary Synonym — Banvel
Date |
Section |
Description |
---|---|---|
08/22/1988 | I.A. | Oral RfD summary replaced; new basis for RfD |
01/01/1990 | VI. | Bibliography on-line |
01/01/1992 | IV. | Regulatory actions updated |
07/01/1992 | I.A.4. | Citation year for 90-day rat study corrected |
07/01/1992 | VI.A. | Reference year corrected |
06/01/1993 | II. | Carcinogenicity assessment under review on 04/01/1993 |
11/01/1993 | II.D.2. | Work group review date added |
08/01/1995 | II., II.D.2. | EPA's RfD/RfC and CRAVE workgroups were discontinued in May, 1995. Chemical substance reviews that were not completed by September 1995 were taken out of IRIS review. The IRIS Pilot Program replaced the workgroup functions beginning in September, 1995. |
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 — Dicamba
CASRN — 1918-00-9
Primary Synonym — Banvel
Last Revised — 09/30/1987
- 1918-00-9
- ACIDO (3,6-DICLORO-2-METOSSI)-BENZOICO
- o-ANISIC ACID, 3,6-DICHLORO-
- BANEX
- BANLEN
- Banvel
- BANVEL 4S
- BANVEL 4WS
- BANVEL CST
- BANVEL D
- BENZOIC ACID, 3,6-DICHLORO-2-METHOXY-
- BRUSH BUSTER
- DIANAT
- DIANATE
- Dicamba
- DICAMBE
- 3,6-DICHLOOR-2-METHOXY-BENZOEIZUUR
- 3,6-DICHLOR-3-METHOXY-BENZOESAEURE
- 3,6-DICHLORO-o-ANISIC ACID
- 2,5-DICHLORO-6-METHOXYBENZOIC ACID
- 3,6-DICHLORO-2-METHOXYBENZOIC ACID
- MDBA
- MEDIBEN
- 2-METHOXY-3,6-DICHLOROBENZOIC ACID
- NA 2769
- VELSICOL 58-CS-11