title: Cadmium and lung cancer mortality accounting for simultaneous arsenic exposure.
abstract: OBJECTIVE
  Prior investigations identified an association between airborne cadmium and lung cancer but questions remain regarding confounding by arsenic, a well-established lung carcinogen.
  
  
  METHODS
  A cadmium smelter population exhibiting excess lung cancer was re-analysed using a retrospective exposure assessment for arsenic (As), updated mortality (1940-2002), a revised cadmium (Cd) exposure matrix and improved work history information.
  
  
  RESULTS
  Cumulative exposure metrics for both cadmium and arsenic were strongly associated making estimation of their independent effects difficult. Standardised mortality ratios (SMRs) were modelled with Poisson regression with the contribution of arsenic to lung cancer risk constrained by exposure-response estimates previously reported. The results demonstrate (1) a statistically significant effect of Cd independent of As (SMR=3.2 for 10 mg-year/m(3) Cd, p=0.012), (2) a substantial healthy worker effect for lung cancer (for unexposed workers, SMR=0.69) and (3) a large deficit in lung cancer mortality among Hispanic workers (SMR=0.27, p=0.009), known to have low lung cancer rates. A supralinear dose-rate effect was observed (contribution to risk with increasing exposure intensity has declining positive slope). Lung cancer mortality was somewhat better predicted using a cadmium burden metric with a half-life of about 20-25 years.
  
  
  CONCLUSIONS
  These findings support an independent effect for cadmium in risk of lung cancer mortality. 1/1000 excess lifetime risk of lung cancer death is predicted from an airborne exposure of about 2.4 μg/m(3) Cd.
authors.affiliation: National Institute for Occupational Safety and Health, Education and Information Division, Cincinnati, OH 45226, USA. rhp9@cdc.gov
authors.forename: Robert M
authors.initials: RM
authors.lastname: Park
authors.forename: Leslie T
authors.initials: LT
authors.lastname: Stayner
authors.forename: Martin R
authors.initials: MR
authors.lastname: Petersen
authors.forename: Melissa
authors.initials: M
authors.lastname: Finley-Couch
authors.forename: Richard
authors.initials: R
authors.lastname: Hornung
authors.forename: Carol
authors.initials: C
authors.lastname: Rice
mesh_terms: D000328:Adult; D001151:Arsenic / Q000633:toxicity*; D002104:Cadmium / Q000633:toxicity*; D002274:Carcinogens, Environmental / Q000633:toxicity*; D006801:Humans; D008175:Lung Neoplasms / Q000139:chemically induced* / Q000401:mortality*; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced* / Q000401:mortality; D016273:Occupational Exposure / Q000009:adverse effects*; D012044:Regression Analysis; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D002274:Carcinogens, Environmental; D002104:Cadmium; D001151:Arsenic