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Ametryn
CASRN 834-12-8
Contents
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 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 NOEL: 10 mg/kg/day 1000 1 9E-3
(converted to mg/kg/day
Rat Subchronic Oral 8.6 mg/kg/day)
Gavage Bioassay
LEL: 100 mg/kg/day
Ciba-Geigy, 1961a (converted to
86 mg/kg/day)
*Conversion Factors: 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 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
Data Base -- Low
RfD -- Low
The principal study is of fair quality and is given a medium confidence
rating. The confidence in the data base is low due to the fact that the data
base 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
___I.A.7. EPA CONTACTS (ORAL RfD)
Please contact the Risk Information Hotline for all questions concerning this
assessment or IRIS, in general, at (513)569-7254 (phone), (513)569-7159 (FAX)
or RIH.IRIS@EPAMAIL.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.
_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.
__VI.B. INHALATION RfD REFERENCES
None
__VI.C. CARCINOGENICITY ASSESSMENT REFERENCES
None
_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
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-
Last updated: 5 May 1998
URL: http://www.epa.gov/iris/SUBST/0208.HTM
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