Do estrogens, wood dust, a common solvent called trichloroethylene, the flavoring methyleugenol and the antibiotic chloramphenicol cause human cancer under some circumstances? The National Toxicology Program, headquartered at the National Institute of Environmental Health Sciences, today sought final public comments and data on these and several other substances and exposures before recommending whether to list them as human carcinogens in the federal government's tenth and newest Report on Carcinogens.

Comments will be accepted for 60 days.

Last year, two federal science committees and one public peer review panel with non-government members looked at eight nominated substances. The three scientific review committees evaluated available, published data relevant to listing these substances as "known" or, with less complete data, as "reasonably anticipated to be" causes of human cancer. Here are the substances reviewed:

• Trichloroethylene. This widely used metal degreasing solvent was unanimously recommended for upgrading from "reasonably anticipated" to listing as a "known" human carcinogen by one government panel, the NIEHS Review Committee, but the upgrade was turned down, 4 to 3, by the second government panel representing other agencies and regulators, and by the public panel. If not upgraded, trichloroethylene would continue to be listed as "reasonably anticipated to be a human carcinogen."

• Estrogens. Steroidal estrogens, which are used in some post-menopausal therapy and as oral contraceptives, were recommended as "known" human carcinogens by unanimous votes of the two government panels and 8 to 1 by the public panel. Conjugated estrogens, a subgroup of the broad group of steroidal estrogens, are already listed as "known" and drug labeling or package inserts discuss the possible side-effects that occur in some people.

• Wood dust. All three panels, after reviewing the data, unanimously recommended woo
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