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PAH carcinogenicity estimation May 28, 2009

Posted by fetzthechemist in PAHs.

In the May 25th, 2009 Chemical and Engineering News, there is a short piece in the Science and Technology Concentrates, on page 34, about how PAH carcinogenicity is estimated.

The US EPA uses a linear correlation between dosage levels of exposure and cancer incidence in test animals. This report describes research done at Oregon State University that shows that the response is nonlinear for the PAH tested, dibenzo{a.l}pyrene. This is an extremely active carcinogenic PAH. Their conclusion is that the EPA’s use of linearity over-estimates carcinogenicity by a factor bewtween 500 and 1,500.

This might be important for other, less-potent PAHs, such as benzo[a]pyene, chrysene, or benz[a]anthracene, since the EPA current limita of one increased cancer occurence out of a million exposures works out to about 1 part-per-million for those PAHs.

But for dibenzo[a,l]pyrene the EPA’s approach shows an activity at about 0.5 parts-per-billion. Even with a 500 to 1,500 higher level, that is 0.25 to 0.75 parts-per-million. This PAH is a nasty one, still.

I did have two quibbles with the piece, or at least with the writing of it. The writer uses the term polyaromatic hydrocarbons, which is explicitly verboten under the ACS Style Guide for publication. It is an archaic term and ought to be the correct polycyclic aromatic hydrocarbon. Also, the PAH name dibenzo[a,l]pyrene is also a trivial name. It ought to be the IUPAC name of dibenzo[def,p]chrysene.



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