Asbestos

Reference Dose for Oral Exposure (RfD) (PDF) (15 pp, 129 K) Last Updated:

Not assessed under the IRIS Program.

Reference Concentration for Inhalation Exposure (RfC) (PDF) (15 pp, 129 K)

Not assessed under the IRIS Program.

Weight of Evidence for Cancer (PDF) (15 pp, 129 K) Last Updated: 09/26/1988

• Observation of increased mortality and incidence of lung cancer, mesotheliomas and gastrointestinal cancer in occupationally exposed workers are consistent across investigators and study populations. Animal studies by inhalation in two strains of rats showed similar findings for lung cancer and mesotheliomas. Animal evidence for carcinogenicity via ingestion is limited (male rats fed intermediate-range chrysotile fibers; i.e., >10 um length, developed benign polyps), and epidemiologic data in this regard are inadequate.
• This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (15 pp, 129 K)

Not Assessed under the IRIS Program.

Inhalation Unit Risk: 2.3 x 10^-1 per f/mL
Extrapolation Method: Additive risk of lung cancer and mesothelioma, using relative risk model for lung cancer and absolute risk model for mesothelioma
Tumor site(s): Respiratory
Tumor type(s): Lung cancer and mesothelioma (Selikoff et al., 1979; Peto et al., 1982; Seidman et al., 1979; Peto, 1980; Finkelstein, 1983)