The summary SMRs for lung cancer and respiratory disease

The summary SMRs for lung cancer and nonmalignant respiratory disease reported here are somewhat lower than those reported by McDonald et al. (2004), partially because my analysis used no tenure exclusion.

More importantly, previous studies of Libby workers excluded those hired after the 1960s; the present study includes workers hired through 1981—that is, workers whose employment began after exposure intensity had been significantly reduced.

Short-term Libby workers display substantial disease

However, the present analysis reveals substantial disease even among workers employed less than 1 year. Short-term workers were 1.6 (95% CI, 1.1–2.1) times more likely to die from lung cancer and 2.1 (95% CI, 1.6–2.8) times more likely to die from nonmalignant respiratory disease than the comparable U.S. population.

Further, even among workers employed less than 1 year, increasing cumulative fiber exposure was observed to predict nonmalignant respiratory disease mortality (not shown). Thus, including the mortality experience of workers employed less than 1 year provides a more realistic picture of the true effect of working at Libby.