Benzo[a]pyrene (BaP)

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

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

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

• 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)

Inhalation Unit Risk: 1 x 10^-3 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, includes application of age-dependent adjustment factors (ADAFs).
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: EPA has concluded that benzo[a]pyrene is carcinogenic by a mutagenic mode of action. Thus, based on the EPA cancer guidelines (2005), the inhalation unit risk (IUR) addressing lifetime exposure includes application of ADAFs. The IUR is recommended for lifetime exposures. EPA has also provided an adult-based cancer unit risk of 6 x 10^-4 per µg/m³. This adult-based cancer unit risk can be used instead of the IUR when assessing cancer risk associated with exposure scenarios that don’t include early life (< 16 years of age) or when other calculations by the user are necessary (e.g., when applying ADAFs to age-specific exposure estimates).