April 7, 1986

Mr. William T. Ayers
2300 28th Street
San Francisco, California 94116

Dear Mr. Ayers:

This is in response to your recent request for information on benzo(a)pyrene (BaP). The answers to your questions are as follows:

(1) Is it a known carcinogen in man?

Although it is considered as such, the International Agency for Research on Cancer (IARC) has classified BaP as a "probable" rather than a "confirmed" human carcinogen. The assessment of the risk of cancer due to exposure to this substance cannot be determined independently since the exposure of human populations to BaP always occurs simultaneously with exposure to mixtures of other compounds of known or possible carcinogenicity (attached are the IARC reports on this subject from their "Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans," Volume 29 and Supplement 4).

(2) Are known carcinogens banned in toto from the air in the workplace?

The Occupational Safety and Health Administration (OSHA) does not "ban" carcinogens or toxic substances from the workplace. OSHA regulates the levels of these materials to which employees may be exposed in the workplace. Some stringent requirements are stipulated for those substances which are either known or suspect carcinogens. As an example, I have enclosed a copy of the OSHA standard for occupational exposure to the carcinogen acrylonitrile for your information.

(3) Is this chemical so banned?

Not by OSHA.

(4) What rules, laws, regulations, etc., cover this topic?

OSHA regulates BaP along with a class of substances known as "coal tar pitch volatiles." Occupational exposure is limited to two tenths of a milligram of coal tar pitch volatiles (benzene soluble fraction) anthracene, BaP, phenathrene, acridine, chrysene, pyrene per cubic millimeter of air (0.2 mg/m(3)) (see the enclosed section of the OSHA General Industry standards, 29 CFR 1910.1000, Table Z-1 and 29 CFR 1910.1002).

I hope this information will be of use to you. Thank you for your interest in occupational safety and health.

Sincerely,



Richard D. Edsell
Director
Office of Science and Technology Assessment