Imazaquin (CASRN 81335-37-7)
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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 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 — 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 One-year Feeding Dog American Cyanamid, 1984a |
NOEL: 25 mg/kg/day LEL: 125 mg/kg/day |
100 |
1 |
2.5E-1 mg/kg/day |
*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 Studies/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
Database — 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 database 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
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 Imazaquin 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 — 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.
_III.
[reserved]
_IV. [reserved]
_V. [reserved]
_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 |
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 — Imazaquin
CASRN — 81335-37-7
Last Revised — 01/31/1987
- 81335-37-7
- AC 252214
- Imazaquin
- Scepter