continued to occur throughout the follow-up period in workers exposed to crocidolite. No evidence of an effect of cumulative exposure to crocidolite on the time to onset of pneumoconiosis. However, progression of pneumoconiosis there was some evidence of effect of cumulative exposure. Authors conclusion: rate of radiographic progression of established asbestosis increases with the accumulated exposure to crocidolite and decreases with time from initial crocidolite exposure to the onset of definite radiographic abnormality Irwig et al Cited by Risk of 1692 mine and mill Crocidolite and Concentration Duration of Morbidity study reporting (1979), Becklake Asbestosis in workers (100% men) Amosite exposure exposure: N=1692 asbestos exposure (1991) Crocidolite and mines/mills n=668 producing irregular ≤20 76=pleural thickening 1 year: n=569 ≤ RMA ID: Amosite in opacities and pleural 20.01-50 fibre/mL 123 =small opacities 1.01-3 year: n=348 000429 South Africa. thickening. Prevalence n=521 (profusion of ≥1/0) 3.01-7 years: n=348 (And an small irregular opacities = >50 fibre/mL erratum) 7.3%; and any pleural 7.01-15 years: n=274 changes = 7.6%. n=281 Prevalence of irregular >15 years: n=146 opacities increased from 2.3% in men exposure for
continued to occur throughout the follow-up period in workers exposed to crocidolite. No evidence of an effect of cumulative exposure to crocidolite on the time to onset of pneumoconiosis. However, progression of pneumoconiosis there was some evidence of effect of cumulative exposure. Authors conclusion: rate of radiographic progression of established asbestosis increases with the accumulated exposure to crocidolite and decreases with time from initial crocidolite exposure to the onset of definite radiographic abnormality Irwig et al (1979), Cited by Becklake (1991) RMA ID: 000429 Risk of Asbestosis in Crocidolite and Amosite in South Africa. (And an erratum) 1692 mine and mill workers (100% men) 76=pleural thickening 123 =small opacities (profusion of ≥1/0) Crocidolite and Amosite mines/mills Concentration exposure ≤20 n=668 20.01-50 fibre/mL n=521 >50 fibre/mL n=274 Duration of exposure: N=1692 ≤ 1 year: n=569 1.01-3 year: n=348 3.01-7 years: n=348 7.01-15 years: n=281 >15 years: n=146 Morbidity study reporting asbestos exposure producing irregular opacities and pleural thickening. Prevalence small irregular opacities = 7.3%; and any pleural changes = 7.6%. Prevalence of irregular opacities increased from 2.3% in men exposure for