Dimethoate (CASRN 60-51-5)
view QuickView

0044
Dimethoate;
CASRN 60-51-5
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 Dimethoate
File First On-Line 01/31/1987
Category (section) |
Status |
Last Revised |
---|---|---|
Oral RfD Assessment (I.A.) | on-line | 09/01/1990 |
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 — Dimethoate
CASRN — 60-51-5
Last Revised — 09/01/1990
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
|
---|---|---|---|---|
Brain ChE inhibition 2-Year Rat Feeding American Cyanamid |
NOEL: 1 ppm diet LEL: 5 ppm diet |
300
|
1
|
2E-4
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)
American Cyanamid Company. 1986a. MRID No. 00164177, 40545501. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Groups of Wistar SPF rats, 50 males and 50 females/group, were fed 0, 1, 5, 25, and 100 ppm (0, 0.05, 0.25, 1.25, and 5.0 mg/kg/day) of dimethoate in their diets for 2 years. A 2-year satellite study (animals were used for clinical chemistry, hematology, and urinalysis), with 15 rats/sex/dose group was also conducted using the same dose levels. There was a dose dependent lowering of cholinesterase activity in the brain in both males and females receiving 5, 25, and 100 ppm. Plasma and RBC cholinesterase activity was also inhibited in males and females receiving 25 and 100 ppm. Mortality was slightly increased in females receiving 100 ppm, and growth was retarded in 100 ppm males during the first half of the study. In rats receiving 100 ppm there was a slight anemia which was predominant in males and an increase in leukocytes in both sexes during the second half of the study.
__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 the lack of a complete database.
MF — None
__I.A.4. Additional Studies/Comments (Oral RfD)
Data Considered for Establishing the RfD
1) 2-Year Feeding (oncogenic) - rat: Principal study - see previous description; core grade guideline
2) Cholinesterase - human: NOEL=0.2 mg/kg/day; LEL=0.4 mg/kg/day (plasma and RBC ChE inhibition); no core grade [Fisons (Canada), Ltd., 1958)
3) 90-Day Feeding - dog: ChE NOEL=2 ppm (0.05 mg/kg/day); ChE LEL=10 ppm (0.25 mg/kg/day) (RBC ChE depression); core grade minimum (American Cyanamid Co., 1968)
4) 3-Generation Reproduction - mouse: Reproductive NOEL=50 ppm (7.5 mg/kg/day) (HDT); core grade minimum (American Cyanamid Co., 1965)
5) Teratology - rat: Maternal NOEL=6 mg/kg/day; Maternal LEL=18 mg/kg/day (hypersensitivity, tremors, and unsteady gait); core grade minimum (Khera et al., 1979)
6) Teratology - rabbit: Maternal NOEL=10 mg/kg/day; Maternal LEL=20 mg/kg/day (decreased body weight); core grade supplementary (American Cyanamid, Co., 1984
Other Data Reviewed:
1) 78-Week Feeding (oncogenic) - mouse: Systemic NOEL=none; LEL=25 ppm (3.75 mg/kg/day) (hepatocyte vacuolization in females); ChE NOEL=none; LEL=25 ppm (3.75 mg/kg/day) (RBC and plasma depressed); at 200 ppm (30 mg/kg/day) (HDT) (liver tumors in females and lung and hemolymphorecticular system tumors in males were observed); core grade minimum (American Cyanamid Co., 1986b)
2) 2-Year Feeding (oncogenic) - rat: NOEL=1 ppm (0.05 mg/kg/day); LEL=10 ppm (0.5 mg/kg/day) (plasma and brain ChE inhibition); core grade supplementary (lack of detailed data disallows for histopathological effect) (American Cyanamid Co., 1970)
Data Gap(s): Chronic Dog Feeding Study; Rabbit Teratology Study
__I.A.5. Confidence in the Oral RfD
Study — High
Database — Medium
RfD — Medium
The critical study is of good quality and is given a high confidence rating. Since a chronic feeding study in a second species is lacking, the database is given a medium confidence rating. Medium confidence in the RfD follows.
__I.A.6. EPA Documentation and Review of the Oral RfD
Registration Standard, 1982
Registration Files
Agency Work Group Review — 07/08/1985, 07/22/1985, 09/29/1986, 03/18/1987, 03/23/1988
Verification Date — 03/23/1988
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 Dimethoate conducted in August 2003 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 — Dimethoate
CASRN — 60-51-5
Not available at this time.
_II. Carcinogenicity Assessment for Lifetime Exposure
Substance Name — Dimethoate
CASRN — 60-51-5
Not available at this time.
_III.
[reserved]
_IV. [reserved]
_V. [reserved]
_VI. Bibliography
Substance Name — Dimethoate
CASRN — 60-51-5
Last Revised — 09/01/1990
_VI.A. Oral RfD References
American Cyanamid Company. 1965. MRID No. 00045816. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
American Cyanamid Company. 1984. MRID No. 00149126. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
American Cyanamid Company. 1968. MRID No. 00075532. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
American Cyanamid Company. 1986a. MRID No. 00164177, 40545501. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
American Cyanamid Company. 1986b. MRID No. 00163800. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
American Cyanamid Company. 1970. MRID No. 00063995. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Fisons (Canada) Ltd. 1958. MRID No. 00055394. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Khera, K.S., C. Whalen, G. Trivett and G. Angers. 1979. Teratogenicity studies on pesticidal formulations of dimethoate, diuron and lindane in rats. Bull. Environ. Contam. Toxicol. 22(4-5): 522-529.
_VI.B. Inhalation RfC References
None
_VI.C. Carcinogenicity Assessment References
None
_VII. Revision History
Substance Name — Dimethoate
CASRN — 60-51-5
Date |
Section |
Description |
---|---|---|
03/01/1988 | I.A.4. | New data entered |
03/01/1988 | I.A.5. | Confidence levels revised |
03/01/1988 | I.A.6. | Review dates added |
03/01/1988 | I.A.6. | Documentation corrected |
06/30/1988 | I.A. | RfD withdrawn |
08/22/1988 | I.A. | Revised oral RfD summary added |
09/01/1990 | I.A.4. | Citations added |
09/01/1990 | IV.F.1. | EPA contact changed |
09/01/1990 | VI. | Bibliography on-line |
01/01/1992 | IV. | Regulatory actions 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. |
10/28/2003 | I.A.6. | Screening-Level Literature Review Findings message has been added. |
_VIII. Synonyms
Substance Name — Dimethoate
CASRN — 60-51-5
Last Revised — 01/31/1987
- 60-51-5
- 8014 Bis HC
- Acetic Acid, O,O-Dimethyldithiophosphoryl-, N-Mono-methylamide Salt
- American Cyanamid 12,880
- BI 58
- CL 12880
- Cygon
- Cygon 4E
- Cygon Insecticide
- Daphene
- De-Fend
- Demos-L40
- Dimethoate
- Dimethogen
- Dimeton
- Dimevur
- ENT 24650
- FIP
- Fosfoto R 35
- Fosfotox
- Fosfotox R
- Fostion MM
- Lurgo
- NCI-C00135
- O,O-Dimethyl S-(N-Methyl- carbamoylmethyl Dithiophosphate
- O,O-Dimethyl S-(N-Methylcarbamoylmethyl) Phosphorodithioate
- PEI 75
- Perfecthion
- Perfekthion
- Phosphamid
- Phosphamide
- Phosphor-odithioic Acid, O,O-Dimethyl S-(2-(Methylamino)-2-Oxoethyl) Ester
- Racusan
- Rogor
- Rogor 20L
- Rogor 40
- Rogor L
- Rogor P
- Roxion
- Sinoratox
- S-Methylcarbamoylmethyl O,O-Dimethyl Phosphorodithioate
- Systoate