Chronic obstructive pulmonary disease mortality in railroad workers.
BACKGROUND
There is little information describing the risk of non-malignant respiratory disease and occupational exposure to diesel exhaust.


METHODS
US railroad workers have been exposed to diesel exhaust since diesel locomotives were introduced after World War II. In a retrospective cohort study we examined the association of chronic obstructive pulmonary disease (COPD) mortality with years of work in diesel-exposed jobs. To examine the possible confounding effects of smoking, multiple imputation was used to model smoking history. A Cox proportional hazards model was used to estimate an incidence rate ratio, adjusted for age, calendar year, and length of follow-up after leaving work (to reduce bias due to a healthy worker survivor effect).


RESULTS
Workers in jobs with diesel exhaust exposure had an increased risk of COPD mortality relative to those in unexposed jobs. Workers hired after the introduction of diesel locomotives had a 2.5% increase in COPD mortality risk for each additional year of work in a diesel-exposed job. This risk was only slightly attenuated after adjustment for imputed smoking history.


CONCLUSIONS
These results support an association between occupational exposure to diesel exhaust and COPD mortality.
Hart
J E
JE
Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA. Jaime.hart@channing.harvard.edu
Laden
F
F
Eisen
E A
EA
Smith
T J
TJ
Garshick
E
E
D000328:Adult; D000395:Air Pollutants, Occupational / Q000009:adverse effects*; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D006801:Humans; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000401:mortality*; D016273:Occupational Exposure / Q000009:adverse effects*; D029424:Pulmonary Disease, Chronic Obstructive / Q000401:mortality*; D011890:Railroads / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012907:Smoking / Q000453:epidemiology; D013997:Time Factors; D014481:United States / Q000453:epidemiology; D001335:Vehicle Emissions / Q000633:toxicity*
D000395:Air Pollutants, Occupational; D001335:Vehicle Emissions