Large volumes, less risk? HPV chemicals may be safer than thought. (Science Selections).
Cunningham and Rosenkranz's analysis follows criteria for toxicity established in the Screening Information Data Set (SIDS) program of the Organisation for Economic Co-operation and Development. This international organization, composed of more than 30 member nations and their chemical industries, created the SIDS program with the goal of screening HPV chemicals for toxicologic end points. The SIDS criteria are also being used for the HPV Chemical Challenge Program of the U.S. Environmental Protection Agency, which asks chemical producers and importers to provide basic toxicologic data on approximately 2,800 HPV chemicals. The criteria include tests for genotoxicity, acute and chronic toxicity, and reproductive toxicity.
With the goal of collecting such data humanely, economically, and efficiently, the Johns Hopkins Center for Alternatives to Animal Testing, ED, Carnegie-Mellon University, and the University of Pittsburgh collaborated in developing the TestSmart Program. The TestSmart Program explores the usefulness of structure-activity relationship modeling, an approach that can be used to predict a chemical's toxicity based on its molecular resemblance to another chemical with an established toxicity. Cunningham and Rosenkranz used the TestSmart method to conduct their research on HPV chemicals.
To investigate whether HPV chemicals as a group are notably toxic or not, Cunningham and Rosenkranz randomly selected 200 such chemicals for which toxicologic data are lacking. They also created a randomly chosen reference set of 10,000 chemicals to represent the universe of chemicals as a whole and serve as a control. Structure-activity relationship modeling was used to screen the chemicals and to predict the proportion within each set that could potentially yield specific end points. The modeling comprised tests for mutagenicity, genotoxicity, acute and chronic toxicity, and environmental fate.
The researchers were surprised to find that the proportion of HPV chemicals predicted to be toxic was significantly less than that in the reference set. Only one toxic end point, sister chromatid exchanges in vitro, which may indicate mutagenicity, was significantly higher in the HPV chemical set as compared to the reference set.
Cunningham and Rosenkranz speculate that the same qualities that make HPV chemicals useful in industry may provide an explanation for their finding. Properties such as stability and low reactivity allow chemicals to retain their function through storage and transport. In general, the researchers theorize, such properties may also relate to lower toxicity.
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|Author:||Barrett, Julia R.|
|Publication:||Environmental Health Perspectives|
|Date:||Sep 1, 2001|
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