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Vernam (CASRN 1929-77-7)

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0201

Vernam; CASRN 1929-77-7

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 Vernam

File First On-Line 03/31/1987

Category (section)
Status
Last Revised
Oral RfD Assessment (I.A.) on-line 01/01/1992*
Inhalation RfC Assessment (I.B.) no data
Carcinogenicity Assessment (II.) no data

*A comprehensive review of toxicological studies was completed (2004) - please see section I.A.6 for more information.

_I.  Chronic Health Hazard Assessments for Noncarcinogenic Effects

_I.A. Reference Dose for Chronic Oral Exposure (RfD)

Substance Name — Vernam
CASRN — 1929-77-7
Last Revised — 01/01/1992

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

2-Generation
Reproduction Rat
Study

Stauffer Chemical
Co., 1983

NOEL: 20ppm (diet)
(1 mg/kg/day)

LEL: 100 ppm (diet)
(5 mg/kg/day)


1000
1
1E-3
mg/kg/day

*Dose Conversion Factors & Assumptions: 1 ppm = 0.05 mg/kg/day (assumed rat food consumption)

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

Stauffer Chemical Company. 1983. MRID No. 00126363, 92193023; HED Doc. No. 005345. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Rats were randomly assigned to one of four treatment groups (consisting of 15 males and 30 females) on the basis of body weight. Vernam was administered in the diet at the following concentrations: 0, 20, 100 or 500 ppm. An LEL of 100 ppm is based on the statistically significant depression in the mean body weight for both parental males and females. The NOEL for reproductive effects is considered to be 500 ppm, since no effects on mating, fertility, gestational or lactational indices were observed. Urinary tract variants were observed at a varied rate in offsprings; whether this effect is compound- related or due to normal variation is not clear without evaluating historical data on this condition.

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

UF — An uncertainty factor of 1000 was used to account for the inter- and intraspecies differences, and the fact that no data on chronic exposure in rats and dogs are available.

MF — None

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

None.

Data Considered for Establishing the RfD:

1) 2-Generation Reproduction - rat: Principal study - see previous description; core grade guideline

2) 2-Year Feeding/Oncogenic - mouse: Systemic NOEL=100 mg/kg/day (HDT); core grade minimum (Stauffer Chemical Co., 1979)

3) 14-Week Feeding - rat: NOEL=32 mg/kg/day (HDT) (no significant effects); no core grade (Stauffer Chemical Co., 1967a)

4) 15-16 Week Feeding - dog: NOEL=1800 ppm (45 mg/kg/day) (HDT) (no significant effects); no core grade (Stauffer Chemical Co., 1967b)

5) Teratology - rabbit: Maternal NOEL=200 mg/kg/day; Toxicity NOEL=200 mg/kg/day; core grade supplementary (Stauffer Chemical Co., 1981)

Data Gap(s): Chronic Dog Feeding Study; Chronic Rat Feeding Study; Rat Teratology Study; Rabbit Teratology Study

__I.A.5. Confidence in the Oral RfD

Study — High
Database — Low
RfD — Low

The principal study is of good quality and is given a high confidence rating. The database is incomplete; therefore, confidence in the database can be considered low to medium. Confidence in the RfD can also be considered low to medium.

__I.A.6. EPA Documentation and Review of the Oral RfD

Pesticide Registration Files

Agency Work Group Review — 09/02/1986, 09/29/1986

Verification Date — 09/29/1986

A comprehensive review of toxicological studies published prior to 2004 was conducted. No new health effects data were identified that would be directly useful in the revision of the existing RfD for Vernam and a change in the RfD is not warranted at this time.

__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 — Vernam
CASRN — 1929-77-7

Not available at this time.

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_II.  Carcinogenicity Assessment for Lifetime Exposure

Substance Name — Vernam
CASRN — 1929-77-7

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 — Vernam
CASRN — 1929-77-7
Last Revised — 01/01/1992

_VI.A. Oral RfD References

Stauffer Chemical Company. 1967a. MRID No. 00088533; HED Doc. No. 000905. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Stauffer Chemical Company. 1967b. MRID No. 00088534; HED Doc. No. 000905. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Stauffer Chemical Company. 1979. MRID No. 00085497, 92193020; HED Doc. No. 000904. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Stauffer Chemical Company. 1981. MRID No. 00076723; HED Doc. No. 005345. Available from EPA. Write to FOI, EPA, Washington, DC 20460.

Stauffer Chemical Company. 1983. MRID No. 00126363, 92193023; HED Doc. No. 005345. 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 —Vernam
CASRN — 1929-77-7

Date
Section
Description
01/01/1992 I.A.4. Citations added
01/01/1992 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.
09/29/2004 I.A.6 Screening-Level Literature Review Findings message has been removed and replaced by comprehensive literature review conclusions.

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_VIII.  Synonyms

Substance Name — Vernam
CASRN — 1929-77-7
Last Revised — 03/31/1987

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