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Development of a Relative Potency Factor (RPF) Approach for Polycyclic Aromatic Hydrocarbon (PAH) Mixtures (External Review Draft)


EPA is announcing a 60-day public comment period and a public listening session for the external review draft document titled, Development of a Relative Potency Factor (RPF) Approach for Polycyclic Aromatic Hydrocarbon (PAH) Mixtures (External Review Draft), as announced in the February 26, 2010 Federal Register Notice.

Report Information

EPA is conducting a peer review and public comment of the scientific basis supporting the human health hazard and dose-response assessment of polycyclic aromatic hydrocarbon (PAH) that when finalized will appear on the Integrated Risk Information System (IRIS) database. Please refer to IRISTrack - polycyclic aromatic hydrocarbon for the latest schedule updates.

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Lynn Flowers
  • by phone at:   703-347-8537
  • by email at:  flowers.lynn@epa.gov


PAHs are of concern as potential human health hazards, because many PAHs are demonstrated tumorigenic agents in animal bioassays and are positive in tests for genotoxicity or DNA damage. PAHs occur in the environment primarily as complex mixtures generated from the combustion of substances containing carbon and hydrogen, and rarely occur in the environment as isolated entities. The draft Relative Potency Factor approach is not a reassessment of individual PAH carcinogenicity, but rather provides a methodology for estimating cancer risk from exposure to PAH mixtures by summing doses of component PAHs after scaling the doses (with RPFs) relative to the potency of an index PAH (i.e., benzo[a]pyrene). The cancer risk is then estimated using the dose-response curve for the index PAH.


Oct 2002EPA sponsored a Peer Consultation Workshop on Approaches to Polycyclic Aromatic Hydrocarbon (PAH) Health Assessment.
Nov 2009EPA hosted an interagency science consultation on the draft of the PAH Mixtures Approach.
Jan 2010SAB releases the names and biosketches of the "Short List Candidates" for the upcoming PAH Mixtures RPF Approach Review Panel.
Feb 2010EPA released the draft document and charge for public review and comment. Additionally, as per the new IRIS process, all comments received from federal agencies and White House offices on draft IRIS assessments will be made publicly available. Accordingly, interagency comments and the interagency draft of the PAH draft report have also been released.
Jun 2010SAB hosted a Teleconference for SAB PAH Mixtures Review Panel - Orientation and held a follow-up SAB PAH Mixtures Review Panel Meeting to discuss the report later in the month. [Federal Register May 18, 2010]
Sep 2010SAB hosted the PAH Mixtures Review Panel Teleconference for the discussion of the draft report. [Federal Register Sep 8, 2010]
Dec 2010SAB hosted a Quality Review of an SAB panel draft report reviewing EPA's IRIS Assessment for Polyaromatic Hydrocarbons. [Federal Register Nov 24, 2010]
Mar 2011SAB released the final report, SAB Review of EPA's "Development of a Relative Potency Factor (RPF) Approach for Polycyclic Aromatic Hydrocarbon (PAH) Mixtures (February 2010 Draft)". (PDF, 47 pp., 696,671 bytes), EPA-SAB-11-004

Next Steps

Following External Peer Review and Public Comment, the final assessment is scheduled to be posted to the IRIS Web site.

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-2010-0047 (for the docket ID).


U.S. EPA. Development of a Relative Potency Factor (RPF) Approach for Polycyclic Aromatic Hydrocarbon (PAH) Mixtures (External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-08/012A, 2010.


This download(s) is distributed solely for the purpose of pre-dissemination peer review under applicable information quality guidelines. It has not been formally disseminated by EPA. It does not represent and should not be construed to represent any Agency determination or policy.

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