Jump to main content.


Imazaquin (CASRN 81335-37-7)

IRIS
List of IRIS Substances




view QuickView

Main Contents

Go

0062

Imazaquin; CASRN 81335-37-7

Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data, as outlined in the IRIS assessment development process. Sections I (Health Hazard Assessments for Noncarcinogenic Effects) and II (Carcinogenicity Assessment for Lifetime Exposure) present the conclusions that were reached during the assessment development process. Supporting information and explanations of the methods used to derive the values given in IRIS are provided in the guidance documents located on the IRIS website.

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
gain, skeletal
myopathy, slight
anemia, bone marrow
hyperplasia, elevated
serum SGOT, SGPT, CPK

One-year Feeding Dog
Study

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).

Top of page


_I.B. Reference Concentration for Chronic Inhalation Exposure (RfC)

Substance Name — Imazaquin
CASRN — 81335-37-7

Not available at this time.

Top of page


_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.

Top of page


_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.

Top of page


_VI.B. Inhalation RfC References

None

Top of page


_VI.C. Carcinogenicity Assessment References

None

Top of page


_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.

Top of page


_VIII.  Synonyms

Substance Name — Imazaquin
CASRN — 81335-37-7
Last Revised — 01/31/1987

Top of page

Recent Additions | Search IRIS | IRIS Home | NCEA Home | ORD Home


Jump to main content.