Exposure–response relationship between lung cancer and polycyclic aromatic hydrocarbons (PAHs)

• Published in: Occupational and environmental medicine (London, England) Vol. 66; no. 11; pp. 740 - 746
• Main Authors: Armstrong, B G, Gibbs, G
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group Ltd 01.11.2009; BMJ Publishing Group; BMJ Publishing Group LTD
• Subjects: Age; Aluminum; Biological and medical sciences; Bladder cancer; Calendars; Carcinogenesis, carcinogens and anticarcinogens; Chemical agents; Cigarette smoking; Cigarettes; Cocarcinogenesis; Dose response relationship; Employment; Epidemiologic Methods; Epidemiology; Estimates; Female; Fluorides; Health risk assessment; Humans; Knots; Lung cancer; Lung neoplasms; Lung Neoplasms - chemically induced; Lung Neoplasms - mortality; Male; Medical sciences; Metallurgy; Mortality; Occupational Diseases - chemically induced; Occupational Diseases - mortality; Occupational Exposure - adverse effects; Occupational Exposure - analysis; Pneumology; Polycyclic aromatic hydrocarbons; Polycyclic Compounds - toxicity; Quebec - epidemiology; Smelters; Smoking; Smoking - adverse effects; Smoking - epidemiology; Studies; Tobacco smoking; Tumors; Tumors of the respiratory system and mediastinum; Workers; United Kingdom; Europe; Quebec; Canada; Quebec Canada; Human; Lung disease; Respiratory disease; Smelting; Toxicity; Lung cancer; Malignant tumor; Polycyclic aromatic compound; Occupational exposure; Epidemiology; Bronchopulmonary; Dose activity relation; Carcinogen; Foundry industry; Cohort study; Bronchus disease; Occupational medicine; Cancer
• ISSN: 1351-0711; 1470-7926
• DOI: 10.1136/oem.2008.043711

Objectives:To estimate the exposure–response function associating polycyclic aromatic hydrocarbon (PAH) exposure and lung cancer, with consideration of smoking.Methods:Mortality, occupational exposure and smoking histories were ascertained for a cohort of 16 431 persons (15 703 men and 728 women) who had worked in one of four aluminium smelters in Quebec from 1950 to 1999. A variety of exposure–response functions were fitted to the cohort data using generalised relative risk models.Results:In 677 lung cancer cases there was a clear trend of increasing risk with increasing cumulative exposure to PAH measured as benzo(a)pyrene (BaP). A linear model predicted a relative risk of 1.35 (95% CI 1.22 to 1.51) at 100 μg/m−3 BaP years, but there was a significant departure from linearity in the direction of decreasing slope with increasing exposures. Among the models tried, the best fitting were a two-knot cubic spline and a power curve (RR = (1+bx)p), the latter predicting a relative risk of 2.68 at 100 μg/m−3 BaP years. Additive models and multiplicative models for combining risks from occupational PAH and smoking fitted almost equally well, with a slight advantage to the additive.Conclusion:Despite the large cohort with long follow-up, the shape of the exposure–response function and the mode of combination of risks due to occupational PAH and smoking remains uncertain. If a linear exposure–response function is assumed, the estimated slope is broadly in line with the estimate from a previous follow-up of the same cohort, and somewhat higher than the average found in a recent meta-analysis of lung cancer studies.