Chlorsulfuron (CASRN 64902-72-3)
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0027
Chlorsulfuron;
CASRN 64902-72-3
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 Chlorsulfuron
File First On-Line 01/31/1987
Category (section) |
Status |
Last Revised |
---|---|---|
Oral RfD Assessment (I.A.) | on-line | 01/01/1990 |
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 — Chlorsulfuron
CASRN — 64902-72-3
Last Revised — 01/01/1990
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
|
---|---|---|---|---|
Decreased body weight 2-Year Rat Study du Pont, 1980a |
NOEL: 100 ppm LEL: 500 ppm |
100
|
1
|
5E-2
mg/kg/day |
*Conversion Factors -- l ppm = 0.05 mg/kg/day (assumed rat food consumption)
__I.A.2. Principal and Supporting Studies (Oral RfD)
E.I. du Pont de Nemours & Company, Inc. 1980a. MRID No. 00031419, 00086003. Available from EPA. Write to FOI, EPA, Washington DC 20460.
Three hundred sixty-eight male and 371 female CD rats were received from Charles River Breeding Laboratories. Following a 12-day pretest, 320 rats of each sex were divided into four groups of 80 males and 80 females and housed in pairs. Groups were fed diets containing 0, 100, 500, or 2500 ppm chlorsulfuron for two years. All rats were examined at least once daily during the first 14 weeks of the study and at least twice daily after that for abnormal behavior and clinical signs of toxicity. Three, 6, 12, 18, and 24 months after initiation of the study, 10 rats from each of the study groups were subjected to clinical chemistry, hematologic and urine analytical examinations. The observed results included a mild to moderate reduction in mean body weights and weight gains in male rats fed 500 ppm or 2500 ppm chlorsulfuron.
__I.A.3. Uncertainty and Modifying Factors (Oral RfD)
UF — A composite 100-fold UF has been used to compensate for both the interspecies differences in extrapolating to humans, and the expected intrahuman variability to the toxicity of this chemical.
MF — None
__I.A.4. Additional Studies/Comments (Oral RfD)
Data Considered for Establishing the RfD
- 2-Year Feeding (oncogenic) - rat: Principal Study - see discussion above; core grade guideline
- 6-Month Feeding - dog: Systemic NOEL=2500 ppm (62.5 mg/kg/day) (HDT); core grade minimum (du Pont, 1980b)
- 3-Generation Reproduction - rat: Reproductive NOEL=500 ppm (25 mg/kg/day); Reproductive LEL=2500 ppm (125 mg/kg/day) (decreased fertility indices); Maternal NOEL=500 ppm; Maternal LEL=2500 ppm (decreased mean body weight); core grade guideline (du Pont, 1980c)
- Teratology - rat: Teratogenic NOEL=2500 ppm (125 mg/kg/day) (HDT); Maternal NOEL=2500 ppm; Fetotoxic NOEL=2500 ppm; core grade minimum (du Pont, 1978)
- Teratology - rabbit: Teratogenic NOEL=75 mg/kg/day; Fetotoxic NOEL=25 mg/kg/day; Fetotoxic LEL=75 mg/kg/day (increased incidence of resorption); core grade minimum (du Pont, 1980d)
Data Gap(s): None
Other Data Reviewed
- 2-Year Feeding (oncogenic) - mice: Systemic NOEL=500 ppm (75 mg/kg/day); Systemic LEL=5000 ppm (decreased body weight and food consumption); core grade guideline (du Pont, 1981)
- 90-Day Feeding - rat: NOEL=100 ppm (5 mg/kg/day) (LDT); LEL=5000 ppm (25 mg/kg/day) (slight decrease in plasma creatinine, slight increased hematocrit); core grade minimum (du Pont, 1980e)
__I.A.5. Confidence in the Oral RfD
Study — High
Database — High
RfD — High
The principal study appears to be of good quality and is given a high rating. Additional studies are also of good quality, and therefore, the database 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 — 04/08/1986
Verification Date — 04/08/1986
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 Chlorsulfuron conducted in November 2001 did not identify any critical new studies. IRIS users who know of important new studies may provide that information to 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 — Chlorsulfuron
CASRN — 64902-72-3
Not available at this time.
_II. Carcinogenicity Assessment for Lifetime Exposure
Substance Name — Chlorsulfuron
CASRN — 64902-72-3
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 — Chlorsulfuron
CASRN — 64902-72-3
Last Revised — 01/01/1990
_VI.A. Oral RfD References
E.I. du Pont de Nemours & Company, Inc. 1978. MRID No. 00031424. Available from EPA. Write to FOI, EPA, Washington DC 20460.
E.I. du Pont de Nemours & Company, Inc. 1980a. MRID No. 00031419, 00086003. Available from EPA. Write to FOI, EPA, Washington DC 20460.
E.I. du Pont de Nemours & Company, Inc. 1980b. MRID No. 00031420. Available from EPA. Write to FOI, EPA, Washington DC 20460.
E.I. du Pont de Nemours & Company, Inc. 1980c. MRID No. 00031423. Available from EPA. Write to FOI, EPA, Washington DC 20460.
E.I. du Pont de Nemours & Company, Inc. 1980d. MRID No. 00086827. Available from EPA. Write to FOI, EPA, Washington DC 20460.
E.I. du Pont de Nemours & Company, Inc. 1980e. MRID No. 00031421. Available from EPA. Write to FOI, EPA, Washington DC 20460.
E.I. du Pont de Nemours & Company, Inc. 1981. MRID No. 00090030. 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 — Chlorsulfuron
CASRN — 64902-72-3
Date |
Section |
Description |
---|---|---|
03/31/1987 | IV. | Regulatory Action section on-line |
01/01/1990 | I.A. | Prinicipal study year corrected |
01/01/1990 | VI. | Bibliography on-line |
01/01/1992 | IV. | Regulatory action updated |
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 — Chlorsulfuron
CASRN — 64902-72-3
Last Revised — 01/31/1987
- 64902-72-3
- BENZENESULFONAMIDE, 2-CHLORO-N-(((4-METHOXY-6-METHYL-1,3,5-;TRIAZIN-2-YL)AMINO) CARBONYL)-
- 2-CHLORO-N-((4-METHOXY-6-METHYL-1,3,5-TRIAZIN-2-YL)AMINOCARBONYL)-BENZENE SULFONAMIDE
- 1-((o-CHLOROPHENYL)SULFONYL)-3-(4-METHOXY-6-METHYL-s-TRIAZIN-2-YL)UREA
- CHLORSULFON
- Chlorsulfuron
- DPX 4189
- GLEAN
- UREA, 1-((o-CHLOROPHENYL)SULFONYL)-3-(4-METHOXY-6-METHYL-s-TRIAZIN-2-YL)-