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Benzo[a]pyrene (BaP)

CASRN 50-32-8 | DTXSID2020139

  • Toxicological Review (PDF) (234 pp, 4.67 M)
  • IRIS Executive Summary (PDF) (9 pp, 671 K)
  • Supplemental Information on the IRIS Toxicological Review of Benzo[a]pyrene

On this page:

  • Key IRIS
    Values
  • Organ/System
    Specific Values
  • Chemical
    Documents
  • Other EPA
    Information

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 (Combined route) 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: 2 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, includes application of age-dependent adjustment factors (ADAFs).
Tumor site(s): Gastrointestinal
Tumor type(s): forestomach, esophagus, tongue, and larynx tumors (Kroese et al. 2001; Beland and Culp, 1998)
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 oral slope factor (OSF) addressing lifetime exposure includes application of ADAFs. The OSF is recommended for lifetime exposures. EPA has also provided an adult-based cancer slope factor of 1 per mg/kg-day. This adult-based cancer slope factor can be used instead of the OSF 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).


Quantitative Estimate of Carcinogenic Risk from Inhalation 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).

Organ/System-Specific RfDs

System RfD (mg/m3) Basis PoD UF Confidence Notes
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
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

Organ/System-Specific RfCs

System RfC (mg/m3) Basis PoD UF Confidence Notes
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

Chemical Documents

Jan 2017: IRIS Toxicological Review of Benzo[A]Pyrene (Final Report) (Report)

Sep 2016: IRIS Toxicological Review of Benzo[a]pyrene (Interagency Science Discussion Draft) (Report)

Sep 2014: IRIS Toxicological Review of Benzo[a]pyrene (External Review Draft) (Report)

Aug 2013: IRIS Toxicological Review of Benzo[a]pyrene (Public Comment Draft) (Report)

Jun 2011: IRIS Toxicological Review of Benzo[a]pyrene (Interagency Science Consultation Draft) (Report)

Sep 1984: Health Effects Assessment for Benzo[a]pyrene (Report)

Other EPA Information

Additional EPA toxicity information may be available by visiting the following sites:
  • Human Health Benchmarks for Pesticides (HHBP). This database provides human health benchmarks for pesticides that may be present in drinking water.
  • Office of Pesticide Programs Pesticide Chemical Search. This database provides links to health effects information and registration status for pesticides.
  • Chemistry Dashboard. This database provides information on chemical structures, experimental and predicted physicochemical, and toxicity data.

Related Links

  • EPA Chemicals Dashboard - Benzo[a]pyrene (BaP)
  • eChemPortal - Benzo[a]pyrene (BaP)

Critical Effects

Developmental
Developmental

Immune
Immune

Reproductive
Reproductive

Tumor Sites

Gastrointestinal
Gastrointestinal

Respiratory
Respiratory

Chemical Structure

Benzo[a]pyrene (BaP)

Synonyms

  • B(A)P
  • BAP
  • BP
  • Benz(a)pyrene
  • Benzo(a)pyrene
  • Benzo(d,e,f)chrysene
  • Benzo[a]pyrene
  • RCRA Waste Number u022
  • 3,4-BP
  • 3,4-Benz(a)pyrene
  • 3,4-Benzopirene
  • 3,4-Benzopyrene
  • 3,4-Benzpyren
  • 3,4-Benzpyrene
  • 3,4-Benzypyrene
  • 50-32-8
  • 6,7-Benzopyrene
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