Fenamiphos (CASRN 22224-92-6)
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0240
Fenamiphos;
CASRN 22224-92-6
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 Fenamiphos
File First On-Line 09/30/1987
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 — Fenamiphos
CASRN — 22224-92-6
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 |
---|---|---|---|---|
ChE inhibition 2-Year Feeding Dog Chemagro Corp., 1972a |
NOEL: 1 ppm diet LEL: 2 ppm diet |
100
|
1
|
2.5E-4
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)
Chemagro Corporation. 1972a. MRID No. 00037965. Available from EPA. Write
to FOI, EPA, Washington, DC 20460.
Fenamiphos (78.8%) was fed to six groups of four male and four female dogs at
dose levels of 0, 0.5, 1, 2, 5, or 10 ppm for 2 years. Blood tests for
sedimentation, hemoglobing, RBC, WBC, hematocrit, differential leukocyte
counts were negative. Liver function test for AP, SGOT, SGPT, Oct, SDH and
serum protein were negative. Cholinesterase activity was depressed at 2, 5
and 10 ppm. Brain cholinesterase was not measured. The NOEL for
cholinesterase inhibition was 1 ppm. No other effects were observed at any
dose level.
__I.A.3. Uncertainty and Modifying Factors (Oral RfD)
UF — An uncertainty factor of 100 has been used to account for both intra-
and interspecies differences.
MF — None
__I.A.4. Additional Studies/Comments (Oral RfD)
Teratogenic studies were positive for rabbits (chain-fused sternebrae).
However, these effects occurred at levels above maternal toxicity and the RfD
(2.5E-4) is 3 orders of magnitude less than the Fetotoxic NOEL (0.3
mg/kg/day). A 2-year feeding/oncogenic study started 2/28/83; results have
not yet been reviewed.
Data Considered for Establishing the RfD:
1) 2-Year Feeding - dog: Principal study - see previous description; core
grade minimum
2) 2-Year Feeding (oncogenic) - rat: Systemic NOEL=10 ppm (0.5 mg/kg/day);
Systemic LEL=30 ppm (1.5 mg/kg/day) (HDT; increased mortality rate, increased
thyroid gland weights and lung weights); ChE NOEL=3 ppm (0.15 mg/kg/day); ChE
LEL=10 ppm (slight ChE inhibition); core grade minimum (pathology evaluation
deficient) (Chemagro Corp., 1972b)
3) 3-Generation Reproduction - rat: Systemic NOEL=10 ppm (0.5 mg/kg/day);
Systemic LEL=30 ppm (1.5 mg/kg/day) (decreased weight gain at F2b males);
Reproductive NOEL=30 ppm (HDT); core grade minimum (Chemagro Corp., 1972c)
4) Teratology - rat: NOEL=0.5 mg/kg/day (HDT); core grade minimum (Mobay
Chemical, 1981)
5) Teratology - rabbit: Maternal NOEL=0.1 mg/kg/day; Maternal LEL=0.3
mg/kg/day (decreased weight gain); Fetotoxic NOEL=0.3 mg/kg/day; Fetotoxic
LEL=1.0 mg/kg/day (HDT) (weight and mortality); core grade guideline (Mobay
Chemical, 1982a)
Other Data Reviewed:
1) 18 Month Oncogenic - mice: Systemic NOEL=none; Systemic LEL=2 ppm (0.3
mg/kg/day) (decreased absolute brain weights); core grade minimum (Mobay
Chemical, 1982b)
2) No delayed neurotoxic effects in hens up to 12.4 mg/kg (Mobay Chemical,
1971)
Data Gap(s): none
__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 and are supportive of the RfD; 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 — 04/08/1986, 11/25/1986, 12/09/1986
Verification Date — 12/09/1986
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 Fenamiphos conducted in November 2001 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 — Fenamiphos
CASRN — 22224-92-6
Not available at this time.
_II. Carcinogenicity Assessment for Lifetime Exposure
Substance Name — Fenamiphos
CASRN — 22224-92-6
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 — Fenamiphos
CASRN — 22224-92-6
Last Revised — 10/01/1990
_VI.A. Oral RfD References
Chemagro Corporation. 1972a. MRID No. 00037965. Available from EPA. Write
to FOI, EPA, Washington, DC 20460.
Chemagro Corporation. 1972b. MRID No. 00038490. Available from EPA. Write
to FOI, EPA, Washington, DC 20460.
Chemagro Corporation. 1972c. MRID No. 00037979. Available from EPA. Write
to FOI, EPA, Washington, DC 20460.
Mobay Chemical Corporation. 1971. MRID No. 00057606. Available from EPA.
Write to FOI, EPA, Washington, DC 20460.
Mobay Chemical Corporation. 1981. MRID No. 00154498. Available from EPA.
Write to FOI, EPA, Washington, DC 20460.
Mobay Chemical Corporation. 1982a. MRID No. 00121286. Available from EPA.
Write to FOI, EPA, Washington, DC 20460.
Mobay Chemical Corporation. 1982b. MRID No. 00098614. 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 — Fenamiphos
CASRN — 22224-92-6
Date |
Section |
Description |
---|---|---|
09/01/1990 | I.A. | Principal study citation corrected |
09/01/1990 | I.A.4. | Citations added |
09/01/1990 | VI. | Bibliography on-line |
10/01/1990 | III.A. | Health Advisory on-line |
10/01/1990 | VI.D. | Health Advisory references added |
01/01/1992 | IV. | Regulatory actions updated |
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 — Fenamiphos
CASRN — 22224-92-6
Last Revised — 09/30/1987
- 22224-92-6
- BAY 68138
- ENT 27572
- ER
- ETHYL 3-METHYL-4-(METHYLTHIO)PHENYL(1-METHYLETHYL)PHOSPHORAMIDATE
- ETHYL 4-(METHYLTHIO)-m-TOLYL ISOPROPYLPHOSPHORAMIDATE
- Fenamiphos
- ISOPROPYLAMINO-O-ETHYL-(4-METHYLMERCAPTO-3-METHYLPHENYL)PHOSPHATE
- 1-(METHYLETHYL)-ETHYL 3-METHYL-4-(METHYLTHIO)PHENYL PHOSPHORAMIDATE
- (3-METHYL-4-(METHYLTHIO)PHENYL) ESTER
- NEMACUR
- NEMACUR P
- NSC 195106
- O-AETHYL-O-(3-METHYL-4-METHYLTHIOPHENYL)-ISOPROPYLAMIDO-PHOSPHORSAEUREEST-
- PHENAMIPHOS
- PHOSPHORAMIDIC ACID, (1-METHYLETHYL)-, ETHYL
- SRA 3886