Document QMkJvyM6OJk0YzqeXR0mx5M5v

s . * *'" * \ 'r * . a; . ricw^.r ,wku ft- A'. <4. isaac: -fey- -? i ' TO : DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE PUBLIC HEALTH SERVICE CENTER FOR DISEASE CONTROL NATIONAL INSTITUTE for OCCUPATIONAL SAFETY and health 1 The Assistant Secretary for Health Through: ES/PHS0 DATE: DEC 1 R 1Q7fi Director, CPC FROM Director, Rational Institute for Occupational Safety and Health SUBJECT: Evaluation of Data on Health Effects of Asbestos Exposure and Revised Recommended Numerical Environmental Limits The National Institute for Occupational Safety and Health (NIOSH) recommends that occupational exposure to all types of asbestos he controlled so that no worker will he exposed to an airborne concentration Of asbestos in excess of 100,000 fibers over 5 pm in length per cubic meter on an 8-hour time-weighted average (TWA) basis. In addition, no worker will be exposed to peak concentrations in excess of 500,000 such fibers per cubic meter of air based on 15-minute sampling periods. Previously, in a criteria document transmitted to the Occupational Safety and Health Administration (OSHA), U.S. Department of Labor, on January 21, 1972, NIOSH recommended that occupational exposure to asbestos be limited to 2,000,000 fibers over 5 pm in length per cubic meter of air, determined as a time-weighted average exposure for an 8-hour workday, and to a peak concentration of 10,000,000 fibers over 5 pm in length per cubic meter, determined by a mininnm sampling time of 15 minutes. That recommended standard was designed primarily to prevent asbestosis. Recognizing that there was then insufficient information to establish a standard to prevent such other asbestos-related diseases as pulmonary, pleural, and peritoneal neoplasms, NIOSH had included in its calculations a safety factor intended to guard against neoplasms more adequately than unmodified environmental limits based solely on prevention of asbestosis. The current recommendation of a stricter standard was formed after review of both the most pertinent publications considered in the 1972 document and papers published during the 5 four years since that document was transmitted to OSHA. The recent literature reviewed has shown that the British standard of 2,000,000 fibers per cubic meter, adopted in 1969 and implemented in Hay of 1970, has not halted the development of radiographic abnormalities of the p chest in workers in asbestos-using establishments. Another study has reported that miners exposed to fibers from aniosite asbestos in airborne concentrations of less than 2,000,000 fibers per cubic meter (average concentration 250,000 fibers per cubic meter) have twice the likelihood of the general population of dying from either malignant or nonmalignant respiratory disease. Other papers have demonstrated that the risk of developing cancer after mixed exposure of factory workers to chrysotile, amositc, and crocidolite asbestoses is dose-related. 4 X i SPNY 003425