title: Exposure to beryllium and occurrence of lung cancer: findings from a cox proportional hazards analysis of data from a retrospective cohort mortality study.
abstract: OBJECTIVE
  The objective was to assess highly confounded patterns in a standardized mortality ratio (SMR) analysis of lung cancer in beryllium worker cohorts.
  
  
  METHODS
  We used Cox proportional hazards single- and multi-variate models to assess confounding and the SMR patterns.
  
  
  RESULTS
  We confirmed the lack of association of lung cancer with time worked. We could not confirm the original study's finding of lung cancer highly associated with earlier plants and or with workers hired in the 1940s compared to the 1950s. The pattern of higher rates of lung cancer with increasing latency was attenuated when covariates were added to the model. We could not exclude that the lower SMR and hazard ratios for workers hired in the 1960s might be related to assumed lower beryllium exposures.
  
  
  CONCLUSIONS
  The patterns observed provide little support for an association of lung cancer with beryllium work factors. This result is likely due to the absence in the original study of a significant overall excess of lung cancer after smoking adjustment.
authors.affiliation: RTI International, Research Triangle Park, NC, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Levy
authors.forename: H Daniel
authors.initials: HD
authors.lastname: Roth
authors.forename: David C
authors.initials: DC
authors.lastname: Deubner