| Occupational Exposure to Crystalline Silica Dust in the United States, 1988-2003 Abdiaziz Yassin,1 Francis Yebesi,2 and Rex Tingle1 1Directorate of Evaluation and Analysis, Office of Evaluations and Audit Analysis, and 2Directorate of Cooperative and State Programs, Office of Outreach Services and Alliances, Occupational Safety and Health Administration, U.S. Department of Labor, Washington, DC, USA Abstract
The purposes of this study were a) to summarize measurements of airborne (respirable) crystalline silica dust exposure levels among U.S. workers, b) to provide an update of the 1990 Stewart and Rice report on airborne silica exposure levels in high-risk industries and occupations with data for the time period 1988-2003, c) to estimate the number of workers potentially exposed to silica in industries that the Occupational Safety and Health Administration (OSHA) inspected for high exposure levels, and d) to conduct time trend analyses on airborne silica dust exposure levels for time-weighted average (TWA) measurements. Compliance inspection data that were taken from the OSHA Integrated Management Information System (IMIS) for 1988-2003 (n = 7,209) were used to measure the airborne crystalline silica dust exposure levels among U.S. workers. A second-order autoregressive model was applied to assess the change in the mean silica exposure measurements over time. The overall geometric mean of silica exposure levels for 8-hr personal TWA samples collected during programmed inspections was 0.077 mg/m3, well above the applicable American Conference of Governmental Industrial Hygienists threshold limit value of 0.05 mg/m3. Surgical appliances supplies industry [Standard Industrial Classification (SIC) 3842] had the lowest geometric mean silica exposure level of 0.017 mg/m3, compared with the highest level, 0.166 mg/m3, for the metal valves and pipe fitting industry (SIC 3494) , for an 8-hr TWA measurement. Although a downward trend in the airborne silica exposure levels was observed during 1988-2003, the results showed that 3.6% of the sampled workers were exposed above the OSHA-calculated permissible exposure limit. Key words: crystalline silica dust, industries, occupations, OSHA IMIS, silica exposure. Environ Health Perspect 113:255-260 (2005) . doi:10.1289/ehp.7384 available via http://dx.doi.org/ [Online 6 December 2004]
Address correspondence to A.S. Yassin, Directorate of Evaluations and Analysis, Office of Evaluations and Audit Analysis, Occupational Safety and Health Administration, U.S. Department of Labor, 200 Constitution Ave. NW, Room N3641, Washington, DC 20210 USA. Telephone: (202) 693-2042. Fax: (202) 693-1641. E-mail: yassin.abdiaziz@dol.gov The opinions expressed in this article do not necessarily represent those of the Occupational Safety and Health Administration. The authors declare they have no competing financial interests. Received 2 July 2004 ; accepted 6 December 2004.
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