Am. J. Respir. Crit. Care Med., Volume 158, Number 3, September 1998, 807-814

Radiographic Evidence of Silicosis Risk in the Diatomaceous Earth Industry

JANET M. HUGHES, HANS WEILL, HARVEY CHECKOWAY, ROBERT N. JONES, MELANIE M. HENRY, NICHOLAS J. HEYER, NOAH S. SEIXAS, and PAUL A. DEMERS

Department of Biostatistics and Epidemiology, and Department of Medicine, Tulane University, New Orleans, Louisiana; Department of Environmental Health, University of Washington, Seattle, Washington; and Occupational Hygiene Programme, University of British Columbia, Vancouver, British Columbia, Canada

There is limited and conflicting evidence regarding the exposure-response relationship between exposure to crystalline silica and silicosis; the level of risk to current workers remains uncertain. We conducted an epidemiologic investigation of 1,809 workers in the diatomaceous earth industry, where exposures to crystalline silica are primarily to the cristobalite form. On the basis of the median of three independent readings, 81 (4.5%) workers were judged to have opacities on chest radiographs (small opacities, profusion  1/0, and/or large opacities). Age-adjusted relative risk of opacities increased significantly with cumulative exposure to crystalline silica. The concentration of respirable crystalline silica to which workers were exposed (highly correlated with period of hire) was an important determinant of risk after accounting for cumulative exposure. For workers with an average exposure to crystalline silica of  0.50 mg/m³ (or hired  1950), the cumulative risk of opacities for a cumulative exposure to crystalline silica of 2.0 mg/m³-yr was approximately 1.1%; for an average exposure > 0.50 mg/m³ (or hired < 1950), the corresponding cumulative risk was 3.7%. These findings indicate an exposure-response relationship between cumulative exposure to crystalline silica and radiographic opacities; moreover, the relationship was substantially steeper among workers exposed at the highest average concentrations of crystalline silica.

This article has been cited by other articles:

				T. Brown Silica exposure, smoking, silicosis and lung cancer--complex interactions Occup. Med., March 1, 2009; 59(2): 89 - 95. [Abstract] [Full Text] [PDF]

				L A Tse, I T S Yu, C C Leung, W Tam, and T W Wong Mortality from non-malignant respiratory diseases among people with silicosis in Hong Kong: exposure-response analyses for exposure to silica dust Occup. Environ. Med., February 1, 2007; 64(2): 87 - 92. [Abstract] [Full Text] [PDF]

				T P Brown and L Rushton Mortality in the UK industrial silica sand industry: 2. A retrospective cohort study Occup. Environ. Med., July 1, 2005; 62(7): 446 - 452. [Abstract] [Full Text] [PDF]

				E Tjoe Nij, A Burdorf, J Parker, M Attfield, C van Duivenbooden, and D Heederik Radiographic abnormalities among construction workers exposed to quartz containing dust Occup. Environ. Med., June 1, 2003; 60(6): 410 - 417. [Abstract] [Full Text] [PDF]

				A 't Mannetje, K Steenland, M Attfield, P Boffetta, H Checkoway, N DeKlerk, and R-S Koskela Exposure-response analysis and risk assessment for silica and silicosis mortality in a pooled analysis of six cohorts Occup. Environ. Med., November 1, 2002; 59(11): 723 - 728. [Abstract] [Full Text] [PDF]

				R Park, F Rice, L Stayner, R Smith, S Gilbert, and H Checkoway Exposure to crystalline silica, silicosis, and lung disease other than cancer in diatomaceous earth industry workers: a quantitative risk assessment Occup. Environ. Med., January 1, 2002; 59(1): 36 - 43. [Abstract] [Full Text] [PDF]

				H. Checkoway, J. M Hughes, H. Weill, N. S Seixas, and P. A Demers Crystalline silica exposure, radiological silicosis, and lung cancer mortality in diatomaceous earth industry workers Thorax, January 1, 1999; 54(1): 56 - 59. [Abstract] [Full Text]