title: Exposure-response relationship between lung cancer and polycyclic aromatic hydrocarbons (PAHs).
abstract: OBJECTIVE
  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 microg/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 microg/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.
  
  
  CONCLUSIONS
  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.
authors: London School of Hygiene and Tropical Medicine, Keppel St, London WC1E 7HT, UK. ben.armstrong@lshtm.ac.uk
authors: B G
authors: BG
authors: Armstrong
authors: G
authors: G
authors: Gibbs
mesh_terms: D003043:Cocarcinogenesis; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000139:chemically induced* / Q000401:mortality; D008297:Male; D008669:Metallurgy; D009784:Occupational Diseases / Q000139:chemically induced* / Q000401:mortality; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis; D011083:Polycyclic Compounds / Q000633:toxicity*; D011792:Quebec / Q000453:epidemiology; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology
chemical_list: D011083:Polycyclic Compounds