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Mepiquat chloride
CASRN 24307-26-4
Contents
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 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 NOEL: 1000 ppm 1000 1 3E-2
tonoclonic spasms; (25 mg/kg/day) mg/kg/day
decreased food
intake and body LEL: 3000 ppm
weights; hematologic (75 mg/kg/day)
effects
90-Day Dog Feeding
Study
BASF Wyandotte
Chemical, 1977a
*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 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
Data Base -- 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
data base 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
___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 -- 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.
_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 RfD 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
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
Last updated: 5 May 1998
URL: http://www.epa.gov/iris/SUBST/0340.HTM
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