Evaluating Impacts of Occupational Exposure Limits for Silica Using G-Estimation

Details

• Personal Author:
  Eisen E ; Picciotto S
• Description:
  Often, the harmful effect of an occupational exposure is difficult to detect in a standard analysis because workers who become ill leave employment sooner, which limits their cumulative exposure. Healthier workers remain employed longer, accumulating more exposure; this contrast makes the exposure appear neutral or beneficial. Using a method of analysis designed to address this issue, we estimated how many years of life were lost due to crystalline silica exposure in the diatomaceous earth industry in Lompoc, California, 1942-2011. The cohort consisted of white men (Hispanic and non-Hispanic), because women and non-white workers in these facilities were too few to study in a meaningful statistical analysis. Workers in the diatomaceous earth industry are exposed to respirable crystalline silica, which is a known lung carcinogen and has also been linked to increased risk of non-malignant respiratory diseases. If workers who died of natural causes had never been exposed to crystalline silica, we estimated that half of them would have lived at least 0.48 (95%CI: 0.02, 1.01) years longer than they actually lived. This estimate was considerably stronger for respiratory causes of death. Those who died of non-infectious non-malignant respiratory diseases (mainly chronic obstructive pulmonary disease) would have lived a median of 3.22 (0.82, 7.75) years longer under no exposure. Similarly, workers who died of lung cancer would have survived a median of 2.21 (0.97, 3.56) years longer in the absence of exposure. These results confirm the known effects of crystalline silica exposure both on lung cancer and on non-malignant respiratory diseases, providing estimates of the numbers of years of life lost due to exposure, rather than estimates of increased risk. That is, we assumed these workers would have died of the same causes even if they had not been exposed to crystalline silica, and this analysis indicates that the exposure shortened their lives substantially. Results for ischemic heart disease were inconsistent, but this may be because the effect of inhaled crystalline silica on this cause of death is smaller than its effect on diseases affecting the lungs, so a larger study population would be needed to obtain reliable results. Completely eliminating exposure to crystalline silica in these workplaces would not be feasible. However, we also found evidence that limiting exposures to 0.025mg/m3, as recommended by the American Conference of Government and Industrial Hygienists, might be nearly as effective for all-cause mortality and would substantially reduce the number of years of life lost due to crystalline silica among workers who die of lung cancer or non-malignant respiratory disease. Workplaces that intervene to comply with this Recommended Exposure Limit can potentially lengthen the lives of at least some of their employees by a significant amount. [Description provided by NIOSH]
• Subjects:
  Cohort Studies Dust Lung Lung Diseases Mortality Neoplasms Occupational Exposure Occupational Health Respiratory System Respiratory Tract Diseases Safety Silicon Dioxide

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• Keywords:
  Chronic Exposure Cohort Studies Crystalline Silica Diatomaceous Earth Exposure Assessment Lung Cancer Mortality Data Occupational Exposure Respirable Dust Respiratory Diseases
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  California ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-21
• NIOSHTIC Number:
  nn:20056987
• NTIS Accession Number:
  PB2019-101422
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R03-OH-010846, 2018 Nov; :1-21
• Contact Point Address:
  Sally Picciotto, Associate Researcher, UC Berkeley School of Public Health, Division of Environmental Health Sciences, 2121 Berkeley Way #5302, Berkeley CA 94720-7360
• Email:
  sallypicciotto@berkeley.edu
• CAS Registry Number:
  Diatomite (CAS RN 61790-53-2) ; Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  2019
• NORA Priority Area:
  Mining
• Performing Organization:
  University of California, Berkeley
• Peer Reviewed:
  False
• Start Date:
  20150901
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20180831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:cdfdfcf9c22be3aa4c3adad8ae0680848263f736f568018217e43a95c019538ece58b1d756b627d51f2983763d1360a80bc938fd68c9ce16cfe3b85f758f18c3
• Download URL:
  https://stacks.cdc.gov/view/cdc/218919/cdc_218919_DS1.pdf
• File Type:
  [PDF - 919.57 KB ]