Benzene

CASRN 71-43-2

Health Hazard Assessments for Effects Other than Cancer


Reference Dose for Oral Exposure (RfD) (PDF) (45 pp, 261 K) last updated: 04/17/2003

RfD (mg/kg-day) System Basis PoD Composite UF Confidence
4.0 x10-3 Immune Decreased lymphocyte count BMDL : 1.2
mg/kg-day
300 Medium

Reference Concentration for Inhalation Exposure (RfC) (PDF) (45 pp, 261 K) last updated: 04/17/2003

RfC (mg/m3) System Basis PoD Composite UF Confidence
3 x10-2 Immune Decreased lymphocyte count BMCL : 8.2
mg/m3
300 Medium

Cancer Assessment


Weight of Evidence for Cancer (PDF) (45 pp, 261 K) last updated: 01/09/2000

WOE Characterization Framework for WOE Characterization
A (Human carcinogen) Guidelines for Carcinogen Risk Assessment (US EPA, 1986)
Known/likely human carcinogen Proposed Guidelines for Carcinogen Risk Assessment (US EPA, 1996)
Basis:
  • Benzene is classified as a "known" human carcinogen (Category A) under the Risk Assessment Guidelines of 1986. Under the proposed revised Carcinogen Risk Assessment Guidelines (U.S. EPA, 1996), benzene is characterized as a known human carcinogen for all routes of exposure based upon convincing human evidence as well as supporting evidence from animal studies. (U.S. EPA, 1979, 1985, 1998; ATSDR, 1997).
  • This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (45 pp, 261 K)

Oral Slope Factor: 1.5 x10 -2 per mg/kg-day to 5.5 x10 -2 per mg/kg-day
Drinking Water Unit Risk: 4.4 x10 -7 per µg/L to 1.6 x10 -6 per µg/L
Extrapolation Method: Linear extrapolation of human occupational data
Tumor site(s): Hematologic
Tumor type(s): Leukemia (Rinsky et al., 1981, 1987 Paustenbach et al., 1993 Crump, 1994 U. S. EPA, 1998 U.S. EPA, 1999)

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (45 pp, 261 K)

Inhalation Unit Risk: 2.2 x10 -6 per µg/m3 to 7.8 x10 -6 per µg/m3
Extrapolation Method: Low-dose linearity utilizing maximum likelihood estimates
Tumor site(s): Hematologic
Tumor type(s): Leukemia (Rinsky et al., 1981, 1987 Paustenbach et al., 1993 Crump and Allen, 1984 Crump, 1992, 1994 U.S. EPA, 1998)

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