US EPA

On February 26, 2010, the draft Development of a Relative Potency Factor (RPF) Approach for Polycyclic Aromatic Hydrocarbon (PAH) Mixtures document and the charge to external peer reviewers were released for external peer review and public comment. The draft document and the charge to external peer reviewers were reviewed internally by EPA and by other federal agencies and White House Offices before public release. In the new IRIS process, introduced by the EPA Administrator, all written comments on IRIS assessments submitted by other federal agencies and White House Offices will be made publicly available. Accordingly, interagency comments and the interagency science consultation draft of the PAH Mixtures Approach and the charge to external peer reviewers are posted on this site.

U.S. EPA. Development of a Relative Potency Factor (RPF) Approach for Polycyclic Aromatic Hydrocarbon (PAH) Mixtures (Interagency Science Consultation Draft) . U.S. Environmental Protection Agency, Washington, DC.

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.

Date	Description
01-Oct 2002	EPA sponsored Peer Consultation Workshop on Approaches to Polycyclic Aromatic Hydrocarbon (PAH) Health Assessment.
02-Nov 2009	EPA hosted an interagency science consultation on the draft of the PAH Mixtures Approach.
03-Jan 2010	SAB releases the names and biosketches of the "Short List Candidates" for the upcoming PAH Mixtures RPF Approach Review Panel.
04-Feb 2010	EPA released the draft of the PAH Mixtures Approach and the charge for public review and comment.

Following external peer review the draft report will be revised taking into consideration external peer review and public comments, will undergo a final EPA internal review and a review by a science discussion with other federal agencies and White House offices, then will be posted to the IRIS Web site.

• Development of a Relative Potency Factor (RPF) Approach for Polycyclic Aromatic Hydrocarbon (PAH) Mixtures (Draft September 2009) (PDF)  (574 pp, 7 MB, about PDF)
• Charge to Reviewers (Draft September 2009) (PDF)  (4 pp, 57 KB, about PDF)
• NASA Comments on PAH Mixtures (PDF)  (2 pp, 30 KB, about PDF)
• NIOSH Comments on PAH Mixtures (PDF)  (1 pp, 9 KB, about PDF)
• OMB Comments on PAH Mixtures (PDF)  (9 pp, 89 KB, about PDF)
• DoD Comments on PAH Mixtures (PDF)  (14 pp, 112 KB, about PDF)
• DoD Comments on PAH Mixtures (Charge to Reviewers) (PDF)  (2 pp, 23 KB, about PDF)

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