Retrospective Assessment of Respirable Quartz Exposure for a Silicosis Study of the Industrial Sand Industry.
Background In 2016, the OSHA PEL for crystalline silica was reduced, renewing interest in evaluating risk of silicosis from occupational exposures. The industrial sand industry, which deals with high-purity quartz sands, is the setting for a current epidemiologic investigation of silicosis risk and...
| Published in: | Annals of Work Exposures & Health Vol. 62; no. 8; pp. 1021 - 1033 |
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| Main Authors: | , , , , |
| Format: | equations & formulas research tables/charts Journal Article |
| Published: |
Oxford University Press / USA
2018
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| Online Access: | View this record in EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=132660715&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 132660715 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 23987308 KJ1E jtl: Annals of Work Exposures & Health issn: 23987308 maglogo: N pubinfo: dt: 2018 vid: 62 iid: 8 pid: 622 pub: Oxford University Press / USA artinfo: ui: 132660715 132660715 132660715 10.1093/annweh/wxy064 132660715 ppf: 1021 ppct: 12 formats: fmt: – @attributes: type: T – @attributes: type: P tig: atl: Retrospective Assessment of Respirable Quartz Exposure for a Silicosis Study of the Industrial Sand Industry. aug: au: Rando, Roy J Kwon, Cheol Woong Vacek, Pamela M Glenn, Robert E Parker, John E affil: Tulane University, School of Public Health & Tropical Medicine, Department of Global Environmental Health Science, New Orleans, LA, USA sug: subj: Silicon Dioxide Pneumoconiosis Epidemiology Occupational Exposure Evaluation Occupational Health Human Retrospective Design Mining Pneumoconiosis Diagnosis Particle Size Respiratory Protective Devices Descriptive Statistics Occupational Exposure Trends Statistical Significance ab: Background In 2016, the OSHA PEL for crystalline silica was reduced, renewing interest in evaluating risk of silicosis from occupational exposures. The industrial sand industry, which deals with high-purity quartz sands, is the setting for a current epidemiologic investigation of silicosis risk and progression. In support of that investigation, respirable quartz (RQ) exposures were retrospectively estimated for 67 workers with silicosis and 167 matched control workers from 21 industrial sand plants, in which some started work as early as 1929. Methods A job exposure matrix (JEM) was constructed by integrating a modern (post-1970) RQ exposure database containing more than 40000 measurements with archival particle count exposure data from a 1947 survey. A simulation algorithm was used to develop a conversion factor to convert the archival particle count data into modern measures of RQ by randomly generating 100000 virtual dust particles of varying diameters corresponding to the size distributions of 14 archival particle size distribution samples. The equivalent respirable mass and particle counts of the virtual particles were calculated, totalled, and ratioed to derive the conversion factor. The JEM was integrated with individual job histories to calculate average and cumulative exposure for each case and control. Multiple exposure estimates were derived for unprotected exposures as well as for exposures adjusted for estimated respiratory protective equipment use and efficiency. Results The mean of the count to respirable mass conversion factors derived from 14 archival particle size samples was 157 µg m−3 per mppcf (SD: 42; range: 96–263) with no statistical difference across process areas (drying, screening, vibrating, binning, bulk loading, bagging), P = 0.29. The JEM demonstrated an industry-wide decrease in prevailing exposures to RQ of up to about 2 orders of magnitude from the distant (1929) to the recent (2012) past. Unadjusted cumulative exposures for cases and controls were statistically different (P < 0.001) with respective medians (range) of 3764 µg m−3 year (221–25121) and 1595 µg m−3 year (0–16446). Adjustment of exposure for use of respiratory protection showed modest reductions in estimated exposure: median adjusted cumulative exposures assuming a protection factor of 5 were 86% and 77% of the unadjusted values for cases and controls, respectively. Conclusions The industrial sand industry offers a unique setting for examination of silicosis risk because of the high silica content of industrial sand and a long history of radiographic silicosis surveillance of industry workers. However, the great majority of silicosis cases in this industry are found among former workers and are associated with exposures occurring in the distant past, which necessitates extensive retrospective exposure assessment and increases the likelihood of exposure misclassification. Nonetheless, the estimated cumulative exposures for silicosis cases and controls in this work were significantly different, with the median cumulative exposure for cases being more than twice that of their matched controls. pubtype: Academic Journal doctype: equations & formulas research tables/charts Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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