- IRIS Summary (PDF) (13 pp, 118 K)
Reference Dose for Oral Exposure (RfD) (PDF) (13 pp, 118 K)
Not assessed under the IRIS Program.
Reference Concentration for Inhalation Exposure (RfC) (PDF) (13 pp, 118 K)
Last Updated: 01/01/1992
Information reviewed but value not estimated.
Weight of Evidence for Cancer (PDF) (13 pp, 118 K)
Last Updated: 08/01/1989
|WOE Characterization||Framework for WOE Characterization|
|B2 (Probable human carcinogen - based on sufficient evidence of carcinogenicity in animals)||Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1986)|
- Based on inadequate human data and sufficient evidence of carcinogenicity in animals; namely significantly increased incidences of benign and malignant tumors at multiple sites in both sexes of mice and a significant increase in thyroid tumors in female rats. There was evidence of mutagenicity in a variety of test systems.
- This may be a synopsis of the full weight-of-evidence narrative.
Oral Slope Factor:
1.7 x 10 -1 per mg/kg-day
Drinking Water Unit Risk: 4.9 x 10 -6 per µg/L
Extrapolation Method: Linearized multistage procedure, extra risk
Tumor site(s): Endocrine
Tumor type(s): Thyroid, C-cell adenoma/ carcinoma (Lijinsky, 1986)
Not Assessed under the IRIS Program.
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