for years, no ≥20 cumulative exposure threshold for parenchymal and pleural fibrosis detected, and parenchymal and pleural progression were still detectable >20 years after the end of exposure. Exposure for month ≥1 was sufficient to produce radiological signs of parenchymal and pleural fibrosis. Those in the lowest cumulative exposure stratum <5 years were found to have high rates of abnormality. Increase in risk of parenchymal abnormality of 6-7% for each fibre/ml-years. Larson et al RMA ID: Vermiculite 1862 mine and Vermiculite Cumulative Fibre Duration of Retrospective cohort Asbestos (2010) 067598 Worker process workers mining and exposure: concentration exposure: mortality study exposure Mortality: processing N=1862; method used: N=1862; producing 69=asbestosis Significantly elevated Estimated operation Median=4.3 Historical air Median=0.8 asbestosis seen deaths SMR for deaths from Effects of sampling data (25th-75th at 8.6 to <44.0 asbestosis =69 Occupational were used to percentile fibre/mL- years (expected=0.5; (tremolite and Exposure estimate the 0.1-4.1 SMR=142.8; actinolite, to Libby years) No smoking Cumulative 95%CI:111.1,180.8) winchite and Amphibole history exposure richterite) average
for ≥20 years, no cumulative exposure threshold for parenchymal and pleural fibrosis detected, and parenchymal and pleural progression were still detectable >20 years after the end of exposure. Exposure for ≥1 month was sufficient to produce radiological signs of parenchymal and pleural fibrosis. Those in the lowest cumulative exposure stratum <5 were found to have high rates of abnormality. Increase in risk of parenchymal abnormality of 6-7% for each fibre/ml-years. Larson et al (2010) RMA ID: 067598 Vermiculite Worker Mortality: Estimated Effects of Occupational Exposure to Libby Amphibole 1862 mine and process workers 69=asbestosis deaths No smoking history Vermiculite mining and processing operation (tremolite and actinolite, winchite and richterite) Cumulative exposure: N=1862; Median=4.3 Cumulative exposure Fibre concentration method used: Historical air sampling data were used to estimate the average Duration of exposure: N=1862; Median=0.8 (25th-75th percentile 0.1-4.1 years) Retrospective cohort mortality study Significantly elevated SMR for deaths from asbestosis =69 (expected=0.5; SMR=142.8; 95%CI:111.1,180.8) Asbestos exposure producing asbestosis seen at 8.6 to <44.0 fibre/mL- years years
asb_reasons10.12.2015.docx