IRIS

Benzo[a]pyrene (BaP)

CASRN 50-32-8

Noncancer Assessment

Reference Dose for Oral Exposure (RfD) (PDF) (9 pp, 671 K) last updated: 01/19/2017

System RfD (mg/kg-day) Basis POD Composite UF Confidence
Developmental 3 x 10-4 Neurobehavioral changes BMDL1SD(HED): 0.092 mg/kg-day 300 Medium

 


Reference Concentration for Inhalation Exposure (RfC) (PDF) (9 pp, 671 K) last updated: 01/19/2017

System RfC (mg/m3) Basis POD Composite UF Confidence
Developmental 2 x 10-6 Decreased embryo/fetal survival LOAEL: 0.0046 mg/m3 3,000 Low/Medium

 

Cancer Assessment

Weight of Evidence for Cancer (PDF) (9 pp, 671 K) last updated: 01/19/2017

WOE Characterization Framework for WOE Characterization
Carcinogenic to humans Guidelines for Carcinogen Risk Assessment (US EPA, 2005)
Basis:
  • Under EPA’s Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005a), benzo[a]pyrene is “carcinogenic to humans” based on strong and consistent evidence in animals and humans.
  • This may be a synopsis of the full weight-of-evidence narrative.

WOE Footnote:  EPA has concluded, by a weight of evidence evaluation, that benzo[a]pyrene (BaP) is carcinogenic by a mutagenic mode of action. Age-dependent adjustment factors (ADAFs) should be used when estimating age-specific cancer risks. See IRIS Summary.


Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (9 pp, 671 K)

Oral Slope Factor: 1 per mg/kg-day
Extrapolation Method: Time-to-tumor dose-response model with linear extrapolation from the POD (BMDL10HED) associated with 10% extra cancer risk.
Tumor site(s): Gastrointestinal
Tumor type(s): forestomach, esophagus, tongue, and larynx tumors (Kroese et al. 2001 Beland and Culp, 1998)



Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (9 pp, 671 K)

Inhalation Unit Risk: 6 x10 -4 per µg/m3
Extrapolation Method: Time-to-tumor dose-response model with linear extrapolation from the POD (BMCL10HED) associated with 10% extra cancer risk.
Tumor site(s): Gastrointestinal, Respiratory
Tumor type(s): Squamous cell neoplasia in the larynx, pharynx, trachea, nasal cavity, esophagus, and forestomach. (Thyssen et al., 1981)


Noncancer Assessment System Specific RfDs

System RfD (mg/kg-day) Basis POD UF Confidence
Developmental 3 x 10-4 Neurobehavioral changes BMDL1SD(HED): 0.092 mg/kg-day 300 Medium
Reproductive 4 x 10-4 Decreased ovarian follicles and ovary weight BMDL1SD(HED): 0.37 mg/kg-day 1000 Medium
Immune 2 x 10-3 Decreased thymus weight and serum IgM BMDL1SD(HED): 1.9 mg/kg-day 1000 Low

 


Noncancer Assessment System Specific RfCs

System RfC (mg/m3) Basis POD UF Confidence
Developmental 2 x 10-6 Decreased embryo/fetal survival LOAEL: 0.0046 mg/m3 3000 Low/Medium
Reproductive 3 x 10-6 Reduced ovulation rate and ovary weight LOAEL: 0.0091 mg/m3 3000 Low/Medium

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