Advertisement

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Environment

Probing Carcinogenicity Limits

A herculean study on 40,000 trout provides the first experimental data for how conservative EPA might be in estimating cancer risk

by Jyllian N. Kemsley
May 25, 2009 | A version of this story appeared in Volume 87, Issue 21

[+]Enlarge
Credit: Gayle Orner/Oregon State University
Rainbow trout fed low doses of DBP help researchers explore the limits of carcinogenicity.
Credit: Gayle Orner/Oregon State University
Rainbow trout fed low doses of DBP help researchers explore the limits of carcinogenicity.

When the Environmental Protection Agency determines exposure limits for genotoxic carcinogens, it typically extrapolates a dose-response line several orders of magnitude below the data cutoff from high-dose toxicity studies. Now, a group led by George S. Bailey of Oregon State University has examined 40,800 rainbow trout to determine the incidence of cancer from exposure to extremely low doses of a polyaromatic hydrocarbon (Chem. Res. Toxicol., DOI: 10.1021/tx9000754). The results provide an experimental estimate for how conservative EPA limits might be for carcinogen exposure. The research team gave sets of trout feed containing 0 to 225 ppm dibenzo[a,l]pyrene (DBP) for four weeks, then returned the fish to a regular diet for nine months before examining them for tumors. The experiments extend the dosages tested by about three orders of magnitude below previous studies and show that DBP dose-response is not linear. When the data were extrapolated to determine how much of the carcinogen will induce one extra cancer case per million animals, the researchers found that the dose of DBP is 500- to 1,500-fold higher than EPA's linear extrapolation from high-dose data, indicating that EPA's method is underestimating the dose and overestimating cancer risk.

Article:

This article has been sent to the following recipient:

0 /1 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.