This means far fewer tests than initially thought are actually needed to produce the required data, EPA says in a status report on its High Production Volume (HPV) Challenge Program. Chemical manufacturing firms are searching the scientific literature to find published data and are combing through their own files for unpublished studies.

Under the HPV initiative, chemical manufacturers are voluntarily testing some 2,800 substances made in or imported into the U.S. in amounts exceeding 1 million lb per year. The aim of the program is to fill in information gaps about basic health and environmental effects of these substances, their environmental fate, and physical properties such as boiling points.

Thus far, existing information fills 94% of the health and environmental data gaps identified for HPV substances, EPA says.

Meanwhile, some test sponsors are proposing to conduct tests to generate information beyond that which EPA is seeking in the HPV program. For instance, sponsors for four chemicals indicated that they would conduct genetic toxicity studies in animals, although those data are not required in the HPV program. In three of these cases, the tests would be used to meet regulatory requirements in countries outside the U.S., EPA says. In the fourth, the sponsor decided to do the study for product stewardship reasons because earlier tests indicated that the compound caused genetic toxicity in cell cultures, according to the agency.

EPA urges companies to explain the rationale for any tests they propose beyond the ones needed in the HPV program. "The lack of an explanation leads to needless speculation about why the tests were proposed and the generation of [public] comments requesting explanations for the proposed tests."

In addition, EPA recommends that basic physicochemical properties such as the boiling point of individual chemicals be measured rather than estimated. These values are plugged into models that calculate environmental transport and other properties, so using estimated figures "multiplies the uncertainty" in model results, according to the agency.

Thus far, 469 companies and 187 consortia of manufacturers have agreed to sponsor 2,155 HPV compounds, the agency says.

EPA plans to get data on all the HPV chemicals, even those that don't have a sponsor volunteering to do testing. The agency will issue regulations requiring those studies and plans to issue one such rule covering 37 substances in the spring of 2002.

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Copyright © 2001 American Chemical Society