Ametryn (CASRN 834-12-8)
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0208
Ametryn;
CASRN 834-12-8
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 Ametryn
File First On-Line 09/30/1987
Category (section) |
Status |
Last Revised |
---|---|---|
Oral RfD Assessment (I.A.) | on-line | 11/01/1989 |
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 — Ametryn
CASRN — 834-12-8
Last Revised — 11/01/1989
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 |
---|---|---|---|---|
Liver toxicity Rat Subchronic Oral Ciba-Geigy, 1961a |
NOEL: 10 mg/kg/day LEL: 100 mg/kg/day (converted to 86 mg/kg/day) |
1000
|
1
|
9E-3
mg/kg/day |
*Conversion Factors and Assumptions — Dose adjusted for treatment schedule (6\days/week).
__I.A.2. Principal and Supporting Studies (Oral RfD)
Ciba-Geigy Corporation. 1961a. MRID No. 00034843. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Rats were dosed with 0, 10, or 100 mg/kg/day ametryn by water gavage, 6 days/week for 13 weeks. The LEL of 100 mg/kg/day is associated with fatty degeneration of the liver. No effects were observed at 10 mg/kg/day. The study appears to have been well-conducted, with 12 males and 12 female rats in each of the two dose groups.
__I.A.3. Uncertainty and Modifying Factors (Oral RfD)
UF — An uncertainty factor of 1000 was used to account for the inter- and intraspecies differences, and to account for the subchronic duration of the critical study.
MF — None
__I.A.4. Additional Studies/Comments (Oral RfD)
Although a rat teratology study had a NOEL of 5 mg/kg/day, it was not used to establish the RfD for the following reasons: 1) The exposure in the teratology study was by gavage, thus exaggerating internal dose when compared with dietary exposures; 2) the NOEL of the rat study used to establish the RfD is not significantly different from the NOEL in the teratology study; and 3) the effects noted at 50 mg/kg/day in the teratology study were minimal and of marginal biological significance.
Data Considered for Establishing the RfD:
1) 90-Day Feeding - rat: Principal study - see previous description
2) 4-Week Feeding (Range Finding) - rat: NOEL=100 mg/kg/day; LEL=250 mg/kg/day (decrease in body weight and bloody nasal secretion) (Ciba-Geigy, 1987a)
3) 90-Day Feeding - dog: NOEL=25 mg/kg/day (Ciba-Geigy, 1961b)
4) Reproduction - rat: NOEL=10 mg/kg/day; LEL=100 mg/kg/day (body weight loss) (Ciba-Geigy, 1987b)
5) Teratology - rat: Maternal and Fetotoxic NOEL=5 mg/kg/day; Maternal and Fetotoxic LEL=50 mg/kg/day (reduction in food consumption and body weight, hypoactivity, elevated forepaw metacarpals not ossified, and increase in salivation and ptosis) (Ciba-Geigy, 1985a)
6) Teratology - rabbit: Maternal NOEL=10 mg/kg/day; Fetotoxic NOEL=60 mg/kg/day (HDT); Maternal LEL=60 mg/kg/day [weight loss (gestational days 7- 10)] (Ciba-Geigy, 1985b)
Data Gap(s): Chronic Dog Feeding Study; Chronic Rat Feeding Study; Rat Reproduction Study (in Progress)
__I.A.5. Confidence in the Oral RfD
Study — Medium
Database — Low
RfD — Low
The principal study is of fair quality and is given a medium confidence rating. The confidence in the database is low due to the fact that the database on chronic toxicity is incomplete and, therefore, the most sensitive toxicologic endpoint cannot be determined. Low confidence in the RfD follows.
__I.A.6. EPA Documentation and Review of the Oral RfD
Pesticide Registration Files
Agency Work Group Review — 05/31/1985, 12/16/1987, 02/18/1987
Verification Date — 02/18/1987
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 Ametryn conducted in September 2002 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 — Ametryn
CASRN — 834-12-8
Not available at this time.
_II. Carcinogenicity Assessment for Lifetime Exposure
Substance Name — Ametryn
CASRN — 834-12-8
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 — Ametryn
CASRN — 834-12-8
Last Revised — 10/01/1990
_VI.A. Oral RfD References
Ciba-Geigy Corporation. 1961a. MRID No. 00034843. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Ciba-Geigy Corporation. 1961b. MRID No. 00048231. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Ciba-Geigy Corporation. 1985a. MRID No. 00153215. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Ciba-Geigy Corporation. 1985b. MRID No. 00153214. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Ciba-Geigy Corporation. 1987a. MRID No. 40382001. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Ciba-Geigy Corporation. 1987b. MRID No. 40349905. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
_VII. Revision History
Substance Name — Ametryn
CASRN — 834-12-8
Date |
Section |
Description |
---|---|---|
03/01/1988 | I.A.4. | Text clarified |
11/01/1989 | I.A.4. | Species corrected in study 4) |
11/01/1989 | VI. | Bibliography on-line |
10/01/1990 | III.A. | Health Advisory on-line |
10/01/1990 | VI.D. | Health Advisory references added |
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 — Ametryn
CASRN — 834-12-8
Last Revised — 09/30/1987
- 834-12-8
- A 1093
- AMETREX
- Ametryn
- AMETRYNE
- CARBAMIC ACID, METHYL-, o-ISOPROPOXYPHENYL ESTER
- CRISATRINE
- 2-ETHYLAMINO-4-ISOPROPYLAMINO-6-METHYLMERCAPTO-s-TRIAZINE
- 2-ETHYLAMINO-4-ISOPROPYLAMINO-6-METHYLTHIO-1,3,5-TRIAZINE
- 2-ETHYLAMINO-4-ISOPROPYLAMINO-6-METHYLTHIO-s-TRIAZINE
- EVIK
- G-34162
- GESAPAX
- 2-METHYLMERCAPTO-4-ETHYLAMINO-6-ISOPROPYLAMINO-S-TRIAZINE
- 2-METHYLMERCAPTO-4-ISOPROPYLAMINO-6-ETHYLAMINO-S-TRIAZINE
- 2-METHYLTHIO-4-ETHYLAMINO-6-ISOPROPYLAMINO-S-TRIAZINE
- N-ETHYL-N'-ISOPROPYL-6-METHYLTHIO-1,3,5-TRIAZINE-2,4-DIYLDIAMINE
- s-TRIAZINE, 2-ETHYLAMINO-4-ISOPROPYLAMINO-6-METHYLTHIO-