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Imazaquin
CASRN 81335-37-7
Contents
0062
Imazaquin; CASRN 81335-37-7
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 Imazaquin
File 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 -- Imazaquin
CASRN -- 81335-37-7
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
-------------------- ----------------------- ----- --- ---------
Decreased body weight NOEL: 25 mg/kg/day 100 1 2.5E-1
gain, skeletal mg/kg/day
myopathy, slight LEL: 125 mg/kg/day
anemia, bone marrow
hyperplasia, elevated
serum SGOT, SGPT, CPK
One-year Feeding Dog
Study
American Cyanamid, 1984a
*Conversion Factors: none
___I.A.2. PRINCIPAL AND SUPPORTING STUDIES (ORAL RfD)
American Cyanamid Company. 1984a. MRID No. 00138972. Available from EPA.
Write to FOI, EPA, Washington, DC 20460.
Imazaquin was administered in the diet at 0, 5, 25, or 125 mg/kg bw/day to
groups of 8 male and 8 female beagle dogs for 1 year. Signs of toxicity noted
at the high dose were: decreased body weight gain; skeletal myopathy; slight
anemia; bone marrow hyperplasia; elevated serum SGOT, SGPT, and CPK; increased
relative liver weight.
___I.A.3. UNCERTAINTY AND MODIFYING FACTORS (ORAL RfD)
UF -- The UF of 100 was used to account for the uncertainties in the
extrapolation from laboratory animals to sensitive humans.
MF -- None
___I.A.4. ADDITIONAL COMMENTS (ORAL RfD)
Data Considered for Establishing the RfD
1) One-year feeding - dog: Principal study - see discussion above; core grade
guideline).
2) 2-Year Feeding (oncogenic) - rat: Systemic NOEL=500 mg/kg/day (HDT); LEL
not established; core grade minimum (American Cyanamid, 1985a)
3) 3-generation Reproduction - rat: Maternal NOEL=1000 mg/kg/day (HDT); LEL
not established; Fetotoxic NOEL=1000 mg/kg/day; LEL not established; core
grade minimum (American Cyanamid, 1985b)
4) Teratology - rabbit: Maternal NOEL=250 mg/kg/day; LEL=500 mg/kg/day
(decreased weight gain); Fetotoxic NOEL=500 mg/kg/day (HDT); LEL not
established; core grade minimum (American Cyanamid, 1984b)
5) Teratology - rat: Maternal NOEL=500 mg/kg/day; LEL=2000 mg/kg/day
(salivation, alopecia, lethargy, flaccidity, 8% mortality); Fetotoxic NOEL=500
mg/kg/day; LEL=2000 mg/kg/day (slight decreased in fetal weight and reduced
ossification of skull bones and unossified hyoids, sternebrae and
metacarpals); core grade guideline (American Cyanamid, 1983)
Data Gap(s): None
Other Data Reviewed
1) 18-Month Oncogenic - mice: Systemic NOEL=150 mg/kg/day; LEL=600 mg/kg/day
(decreased body weight gain in females); core grade guideline (American
Cyanamid, 1985c)
___I.A.5. CONFIDENCE IN THE ORAL RfD
Study -- High
Data Base -- High
RfD -- High
The principal study appears to be of good quality and is given a high
confidence rating. Additional studies are of good quality; therefore, the
data base is given a high confidence rating. High confidence in the RfD
follows.
___I.A.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD
Pesticide Registration Files
Agency Work Group Review -- 06/10/1986
Verification Date -- 06/10/1986
___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 -- Imazaquin
CASRN -- 81335-37-7
Not available at this time.
_II. CARCINOGENICITY ASSESSMENT FOR LIFETIME EXPOSURE
Substance Name -- Imazaquin
CASRN -- 81335-37-7
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 -- Imazaquin
CASRN -- 81335-37-7
Last Revised -- 09/01/1990
__VI.A. ORAL RfD REFERENCES
American Cyanamid Company. 1983. MRID No. 00131552.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
American Cyanamid Company. 1984a. MRID No. 00138972.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
American Cyanamid Company. 1984b. MRID No. 00147011.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
American Cyanamid Company. 1985a. MRID No. 00146205.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
American Cyanamid Company. 1985b. MRID No. 00147016.
Available from EPA. Write to FOI, EPA, Washington, DC 20460.
American Cyanamid Company. 1985c. MRID No. 00146206.
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 -- Imazaquin
CASRN -- 81335-37-7
-------- -------- --------------------------------------------------------
Date Section Description
-------- -------- --------------------------------------------------------
09/01/1990 I.A.4. Citations added
09/01/1990 VI. Bibliography on-line
VIII. SYNONYMS
Substance Name -- Imazaquin
CASRN -- 81335-37-7
Last Revised -- 01/31/1987
81335-37-7
AC 252214
Imazaquin
Scepter
Last updated: 5 May 1998
URL: http://www.epa.gov/iris/SUBST/0062.HTM
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