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Environmental Assessment

IRIS Toxicological Review of Benzo(a)pyrene (Public Comment Draft)

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Report Information

EPA is developing an Integrated Risk Information System (IRIS) assessment of benzo[a]pyrene and has released the draft assessment for public comment and external peer review. When final, the assessment will appear on the IRIS database. Please refer to IRISTrack - Benzo[a]pyrene for the latest schedule updates.

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Kathleen Newhouse
  • by phone at:   206-553-1586
  • by email at:  newhouse.kathleen@epa.gov


Benzo[a]pyrene is a five-ring polycyclic aromatic hydrocarbon that is relatively insoluble in water and has low volatility. It is ubiquitous in the environment primarily as a result of incomplete combustion emissions. Natural sources of benzo[a]pyrene include forest fires and volcanoes, and anthropogenic sources include stoves/furnaces burning fossil fuels (especially wood and coal), motor vehicle exhaust, and various industrial combustion processes. Major sources of occupational exposure involve production of aluminum, coke, graphite and silicon carbide, as well as coal tar distillation. Major sources of non-occupational exposure involve tobacco products and diet (e.g., barbequed or charred meats).

This public comment draft is a reassessment of an IRIS assessment posted in 1987 and includes an oral reference dose, inhalation reference concentration, oral slope factor, inhalation unit risk, and dermal slope factor. It is the first IRIS assessment to propose a dermal slope factor.


Jun 2011EPA initiated the interagency science consultation on the draft Toxicological Review of Benzo[a]pyrene.
Jun 2012A revised interagency science consultation draft Toxicological Review of Benzo[a]pyrene was provided for further review by other federal agencies and the Executive Office of the President.
Aug 2013EPA released the public comment draft for review and comments. EPA also released the interagency science consultation documents, comments from reviewers, and EPA's response to major comments (see "related links"). [Federal Register Notice: Aug 21, 2013]
Sep 2013EPA announced an extension of the public comment period from October 21, 2013 to November 21, 2013. Additionally, EPA reposted the draft Toxicological Review and included an errata sheet detailing the update of the correction. [Federal Register Notice: Oct 24, 2013]
Oct 2013EPA announced an extension of the public comment period to November 21, 2013 [Federal Register Notice Oct 24, 2013]. As a result, EPA moved benzo[a]pyrene (BaP) onto the agenda at the December Bimonthly IRIS public meeting (scheduled for December 12-13, 2013). Information on this meetings is available on the IRIS public meeting page.
Dec 2013EPA held a public meeting to engage stakeholders in early discussions on the draft IRIS assessment and draft charge.
Jan 2014EPA announced a request for nominations for experts to augment the SAB CAAC committee for the upcoming review of the draft benzo[a]pyrene assessment. [Federal Register Notice Jan 28, 2014].

Next Steps

Following public comment and external peer review, the assessment will be revised taking into consideration peer review and public comments. The assessment will then undergo a final EPA internal review and a review by other federal agencies and the Executive Office of the President. Once final, the assessment will be posted to the IRIS database.

Additional Information

Comments on the assessment may be submitted and reviewed using the e-Government Regulations.gov Web site. From the site, select Environmental Protection Agency and the key word EPA- HQ-ORD-2011-0391 (for the docket ID).


U.S. EPA. IRIS Toxicological Review of Benzo(a)pyrene (Public Comment Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-13/138a-b, 2013.


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