Mepiquat chloride (CASRN 24307-26-4)
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0340
Mepiquat chloride; CASRN 24307-26-4
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 Mepiquat chloride
File First On-Line 08/22/1988
Category (section) |
Status |
Last Revised |
---|---|---|
Oral RfD Assessment (I.A.) | on-line | 04/01/1991 |
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 — Mepiquat chloride
CASRN — 24307-26-4
Last Revised — 04/01/1991
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 |
---|---|---|---|---|
Sedation and 90-Day Dog Feeding BASF Wyandotte |
NOEL: 1000 ppm (25 mg/kg/day) LEL: 3000 ppm (75 mg/kg/day) |
1000
|
1
|
3E-2
mg/kg/day |
* Conversion Factors: 1 ppm = 0.025 mg/kg/day (assumed dog food consumption)
__I.A.2. Principal and Supporting Studies (Oral RfD)
BASF Wyandotte Chemical Corporation. 1977a. MRID No. 00135720. Available from EPA. Write to FOI, EPA, Washington, DC 20460.
Mepiquat chloride was fed to pure bred beagle dogs (4/sex/dose level), 10 months of age, for 90 days in the diet at 0, 100, 300, 1000, and 3000 ppm (0, 2.5, 7.5, 25, and 75 mg/kg/day). No effects were observed at the 100, 300, and 1000 ppm dose levels. At 3000 ppm (75 mg/kg/day), HDT, effects included the following: sedation and tonoclonic spasms; decreased food intake and body weights; decreased hemoglobin and RBC; and increased hematocrit and reticulocytes. The NOEL for systemic toxicity is therefore established at 1000 ppm (25 mg/kg/day).
__I.A.3. Uncertainty and Modifying Factors (Oral RfD)
UF — An uncertainty of 100 was used to account for the inter- and intraspecies differences. An additional UF of 10 was used to account for the lack of a chronic dog feeding study and for the extrapolation from subchronic to chronic.
MF — None
__I.A.4. Additional Studies/Comments (Oral RfD)
Data Considered for Establishing the RfD
1) 90-Day Feeding - dog: Principal study - see previous description; core grade guideline ( BASF Wyandotte Chemical, 1977a)
2) 2-Year Feeding (oncogenic) - rat: Systemic NOEL=1000 ppm (50 mg/kg/day); Systemic LEL=3000 ppm (150 mg/kg/day) (decreased food intake and body weight gain); core grade minimum (BASF Wyandotte Chemical Corp., 1979a)
3) 3-Generation Reproduction and Teratology Study - rat: Maternal and Developmental NOEL=3191 ppm (340 mg/kg/day; value determined by the Registrant) (HDT); LEL=none; core grade minimum (BASF Wyandotte Chemical Corp., 1979b)
Other Data Reviewed:
1) 2-Year Feeding (oncogenic) - mouse: Systemic NOEL=1000 ppm (150 mg/kg/day); Systemic LEL=3000 ppm (450 mg/kg/day) (HDT; increased incidence of leucocytes in males and serum free cholesterol in females); core grade minimum (BASF Wyandotte Chemical Corp., 1979c)
2) 90-Day Feeding - rat: NOEL=100 ppm (50 mg/kg/day); LEL=3000 ppm (150 mg/kg/day) (HDT; decreased body weight and food consumption in both sexes; decreased absolute weights of heart, kidneys, liver, lungs, and spleen in males); core grade minimum (BASF Wyandotte Chemical Corp., 1977b)
Data Gap(s): Chronic Dog Feeding Study; Rabbit Teratology Study
__I.A.5. Confidence in the Oral RfD
Study — High
Database — Medium
RfD — Medium
The critical study is of good quality and is given a high confidence rating. Since a chronic study testing the more sensitive species (dog) is missing, the database is given a medium confidence rating. Medium confidence in the RfD follows.
__I.A.6. EPA Documentation and Review of the Oral RfD
Source Document — This assessment is not presented in any existing U.S. EPA document.
Other EPA Documentation — Pesticide Registration Files
Agency Work Group Review — 02/25/1988
Verification Date — 02/25/1988
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 Mepiquat chloride conducted in September 2002 identified one or more significant new studies. IRIS users may request the references for those studies from 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 — Mepiquat chloride
CASRN — 24307-26-4
Not available at this time.
_II. Carcinogenicity Assessment for Lifetime Exposure
Substance Name — Mepiquat chloride
CASRN — 24307-26-4
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 — Mepiquat chloride
CASRN — 24307-26-4
Last Revised — 10/01/1989
_VI.A. Oral RfD References
BASF Wyandotte Chemical Corporation. 1977a. MRID No. 00135720. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
BASF Wyandotte Chemical Corporation. 1977b. MRID No. 00135719. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
BASF Wyandotte Chemical Corporation. 1979a. MRID No. 00083567. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
BASF Wyandotte Chemical Corporation. 1979b. MRID No. 00081316. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
BASF Wyandotte Chemical Corporation. 1979c. MRID No. 00083567. Available from EPA. Write to FOI, EPA, Washington D.C. 20460.
_VI.B. Inhalation RfC References
None
_VI.C. Carcinogenicity Assessment References
None
_VII. Revision History
Substance Name — Mepiquat chloride
CASRN — 24307-26-4
Date |
Section |
Description |
---|---|---|
08/22/1988 | I.A. | Oral RfD summary on-line |
10/01/1989 | VI. | Bibliography on-line |
04/01/1991 | I.A. | Text edited |
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 — Mepiquat chloride
CASRN — 24307-26-4
Last Revised — 08/22/1988
- 24307-26-4
- BAS-083
- BAS-08300W
- BAS 08301W
- BAS 08305 W
- BAS 08306 W
- BAS 08307 W
- BAS85559X
- 1,1-dimethylpiperidinium chloride
- Mepiquat chloride
- N,N-dimethyl-piperidinium chloride
- piperidinium, 1,1-dimethyl-, chloride
- pix
- terpal