How these exposures lead to lung cancer
All three substances follow the same destructive path: inhalation deposits carcinogenic material deep in lung tissue, triggering chronic inflammation, oxidative stress, and DNA damage that accumulates over the years into malignancy.
The research on railroad workers is specific and substantial. A 38-year study of more than 54,000 U.S. railroad workers found a 40% increased lung cancer mortality risk in diesel-exposed jobs. A separate cohort of 55,407 railroad workers found that workers with the longest diesel exposure had a 45% increased lung cancer risk, a finding that held even after accounting for asbestos exposure. A case-control study found that workers with 20 years of diesel-exposed employment carried an odds ratio of 1.41 for lung cancer death.
Asbestos amplifies that risk further. Asbestos is a Group 1 (carcinogenic to humans) lung carcinogen according to the International Agency for Research on Cancer, with risk increasing with cumulative exposure. Creosote, used extensively on railroad ties and wooden structures, contains high concentrations of polycyclic aromatic hydrocarbons, compounds the EPA and ATSDR identify as DNA-damaging carcinogens associated with increased cancer risk.