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Diphenamid (CASRN 957-51-7)

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0232

Diphenamid; CASRN 957-51-7

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 Diphenamid

File First On-Line 09/30/1987

Category (section)
Status
Last Revised
Oral RfD Assessment (I.A.) on-line 03/01/1991
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 — Diphenamid
CASRN — 957-51-7
Last Revised — 03/01/1991

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

Liver toxicity

2-Year Dog Feeding
Study

Upjohn Co., 1966a

NOEL: 3 mg/kg/day

LEL: 10 mg/kg/day

100
1
3E-2
mg/kg/day

*Conversion Factors -- none

__I.A.2. Principal and Supporting Studies (Oral RfD)

Upjohn Company. 1966a. MRID No. 00076382. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Groups of purebred beagle dogs, 3 of each sex, were fed 0, 3, 10, or 30 mg/kg/day diphenamid for 2 years. Daily observations were made for the occurrence of untoward clinical signs, changes in food consumption, behavioral changes, stool consistency, urinary excretion, and indications of emesis. Histopathologic observations revealed no distinction between treated and control dogs, with the exception of an increase in portal macrophages and fibroblasts in the 10 and 30 mg/kg/day groups. A slight increase in liver weight occurred in the 10 and 30 mg/kg/day groups. At 30 mg/kg/day these effects were noted in a greater number of dogs.

__I.A.3. Uncertainty and Modifying Factors (Oral RfD)

UF — Based on a chronic exposure study, an uncertainty factor of 100 was used to account for the inter- and intraspecies differences.

MF — None

__I.A.4. Additional Studies/Comments (Oral RfD)

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 mg/kg/day; Systemic LEL=30 mg/kg/day (increase of liver (male and female) and thyroid (female) weight); core grade supplementary (Upjohn Co., 1966b)

3) 3-Generation Reproduction - rat: Fetotoxic NOEL=10 mg/kg/day; Fetotoxic LEL=30 mg/kg/day (liver congestion, hepatic cell glycogen depletion and irregular hepatic cell size); core grade minimum (Upjohn, 1966c)

Data Gap(s): Rat Teratology Study; Rabbit Teratolgy Study

__I.A.5. Confidence in the Oral RfD

Study — Medium
Database — Medium
RfD — Medium

The principal study appears to be of acceptable quality and is given a medium confidence rating. The database on chronic toxicity is incomplete, and is, therefore, given a medium confidence. Medium 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, 03/18/1987

Verification Date — 03/18/1987

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 Diphenamid conducted in September 2002 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).

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

Substance Name — Diphenamid
CASRN — 957-51-7

Not available at this time.

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_II.  Carcinogenicity Assessment for Lifetime Exposure

Substance Name — Diphenamid
CASRN — 957-51-7

This substance/agent has not undergone a complete evaluation and determination under US EPA's IRIS program for evidence of human carcinogenic potential.

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_III.  [reserved]
_IV.  [reserved]
_V.  [reserved]


_VI.  Bibliography

Substance Name — Diphenamid
CASRN — 957-51-7
Last Revised — 03/01/1991

_VI.A. Oral RfD References

Upjohn Company. 1966a. MRID No. 00076382. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Upjohn Company. 1966b. MRID No. 00076381. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Upjohn Company. 1966c. MRID No. 00076383. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

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_VI.B. Inhalation RfC References

None

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_VI.C. Carcinogenicity Assessment References

None

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_VII.  Revision History

Substance Name — Diphenamid
CASRN — 957-51-7

Date
Section
Description
04/01/1989 III. Health Advisory on-line
03/01/1991 I.A. Principal study year corrected
03/01/1991 I.A.4. Citations added
03/01/1991 III.A.5. Principal study year corrected
03/01/1991 VI. Bibliography on-line
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.

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_VIII.  Synonyms

Substance Name — Diphenamid
CASRN — 957-51-7
Last Revised — 09/30/1987

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