Diesel exhaust and respiratory dust exposure in miners and chronic obstructive pulmonary disease (COPD) mortality in DEMS II

Andreas M Neophytou; Jacqueline M Ferguson; Sadie Costello; Sally Picciotto; John R Balmes; Stella Koutros; Debra T Silverman; Ellen A Eisen

doi:10.1016/j.envint.2024.108528

Diesel exhaust and respiratory dust exposure in miners and chronic obstructive pulmonary disease (COPD) mortality in DEMS II

Environ Int. 2024 Mar:185:108528. doi: 10.1016/j.envint.2024.108528. Epub 2024 Feb 24.

Authors

Andreas M Neophytou¹, Jacqueline M Ferguson², Sadie Costello³, Sally Picciotto³, John R Balmes⁴, Stella Koutros⁵, Debra T Silverman⁵, Ellen A Eisen³

Affiliations

¹ Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA. Electronic address: Andreas.Neophytou@colostate.edu.
² Division of Primary Care and Population Health, Stanford University School of Medicine, Stanford, CA, USA; Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, CA, USA.
³ Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, CA, USA.
⁴ Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, CA, USA; Department of Medicine, University of California, San Francisco, CA, USA.
⁵ Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute (NCI), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Bethesda, MD, USA.

PMID: 38422874
PMCID: PMC10961191 (available on 2025-03-01)
DOI: 10.1016/j.envint.2024.108528

Abstract

Background: Diesel exhaust and respirable dust exposures in the mining industry have not been studied in depth with respect to non-malignant respiratory disease including chronic obstructive pulmonary disease (COPD), with most available evidence coming from other settings.

Objectives: To assess the relationship between occupational diesel exhaust and respirable dust exposures and COPD mortality, while addressing issues of survivor bias in exposed miners.

Methods: The study population consisted of 11,817 male workers from the Diesel Exhaust in Miners Study II, followed from 1947 to 2015, with 279 observed COPD deaths. We fit Cox proportional hazards models for the relationship between respirable elemental carbon (REC) and respirable dust (RD) exposure and COPD mortality. To address healthy worker survivor bias, we leveraged the parametric g-formula to assess effects of hypothetical interventions on both exposures.

Results: Cox models yielded elevated estimates for the associations between average intensity of REC and RD and COPD mortality, with hazard ratios (HR) corresponding to an interquartile range width increase in exposure of 1.46 (95 % confidence interval (CI): 1.12, 1.91) and 1.20 (95 % CI: 0.96, 1.49), respectively for each exposure. HRs for cumulative exposures were negative for both REC and RD. Based on results from the parametric g-formula, the risk ratio (RR) for COPD mortality comparing risk under an intervention eliminating REC to the observed risk was 0.85 (95 % CI: 0.55, 1.06), equivalent to an attributable risk of 15 %. The corresponding RR comparing risk under an intervention eliminating RD to the observed risk was 0.93 (95 % CI: 0.56, 1.31).

Conclusions: Our findings, based on data from a cohort of nonmetal miners, are suggestive of an increased risk of COPD mortality associated with REC and RD, as well as evidence of survivor bias in this population leading to negative associations between cumulative exposures and COPD mortality in traditional regression analysis.

Keywords: COPD mortality; Diesel exhaust; Respiratory dust; Survivor bias.

MeSH terms

Air Pollutants, Occupational* / toxicity
Carbon / analysis
Dust / analysis
Humans
Male
Occupational Exposure* / adverse effects
Occupational Exposure* / analysis
Pulmonary Disease, Chronic Obstructive* / chemically induced
Vehicle Emissions / analysis

Substances

Air Pollutants, Occupational
Vehicle Emissions
Carbon
Dust

Grants and funding

Z99 CA999999/ImNIH/Intramural NIH HHS/United States