IRIS

Benzo[a]pyrene (BaP)

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): 9.2 x 10-2
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 : 4.6 x 10-3
mg/m3 		3000 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 (U.S. EPA, 2005)
Basis:
  • Under EPA’s Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005), 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.

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 (BMDL10(HED)) 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)
Note: ADAF -- EPA has concluded that benzo[a]pyrene is carcinogenic by a mutagenic mode of action. Application of age-dependent adjustment factors (ADAFs) to the oral slope factor is recommended in combination with appropriate exposure data when assessing risk associated with early-life exposure.

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

Inhalation Unit Risk: 6 x 10-4 per µg/m3
Extrapolation Method: Time-to-tumor dose-response model with linear extrapolation from the POD ((BMCL10(HED)) associated with 10% extra cancer risk.
Tumor site(s): Respiratory, Gastrointestinal
Tumor type(s): Squamous cell neoplasia in the larynx, pharynx, trachea, nasal cavity, esophagus, and forestomach. (Thyssen et al., 1981)
Note: ADAF -- EPA has concluded that benzo[a]pyrene is carcinogenic by a mutagenic mode of action. Application of age-dependent adjustment factors (ADAFs) to the inhalation unit risk is recommended in combination with appropriate exposure data when assessing risk associated with early-life exposure.

Organ/System-Specific RfDs

System RfD (per mg/kg-day) Basis POD UF Confidence
Developmental 3 x 10-4 Neurobehavioral changes BMDL1SD (HED): 9.2 x 10-2
mg/kg-day 		300 Medium
Reproductive 4 x 10-4 Decreased ovarian follicles and ovary weight BMDL1SD (HED): 3.7 x 10-1
per mg/kg-day 		1000 Medium
Immune 2 x 10-3 Decreased thymus weight and serum IgM BMDL1SD (HED): 1.9
per mg/kg-day 		1000 Low

 

Organ/System-Specific RfCs

System RfC (mg/m3) Basis POD UF Confidence
Developmental 2 x 10 -6 Decreased embryo/fetal survival LOAEL : 4.6 x 10-3
mg/m3 		3000 Low/Medium
Reproductive 3 x 10 -6 Reduced ovulation rate and ovary weight LOAEL : 9.1 x 10-3
mg/m3 		3000 Low/Medium
Additional EPA toxicity information may be available by visiting the following sites:

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Related Links

Critical Effect Systems

Developmental
Developmental
 
Immune
Immune
Reproductive
Reproductive
 

Tumor Sites

Gastrointestinal
Gastrointestinal
 
Respiratory
Respiratory

Chemical Structure for
Benzo[a]pyrene (BaP)

Benzo[a]pyrene (BaP)

Synonyms