Asbestos-related diseases persist, because millions of workers have had prior 
exposure and many industrializing countries continue to use asbestos. Globally, 
an estimated 107,000 people die annually from lung cancer, malignant 
mesothelioma, and asbestosis due to occupational asbestos exposure. Malignant 
mesothelioma and lung cancer are caused by all major types of asbestos. Asbestos 
causes more lung cancer deaths than malignant mesothelioma of the pleura; most 
cases of the latter are due to asbestos exposure. The cancer risk increases with 
cumulative asbestos exposure, with increased risk even at low levels of exposure 
to asbestos. Based on empirical studies, an estimated cumulative occupational 
exposure to asbestos of 1 fiber/mL-year substantially raises malignant 
mesothelioma risk. No safe threshold for asbestos exposure has been established 
for lung cancer and mesothelioma. The validity of fiber-type risk assessments 
depends critically on the quality of exposure assessments, which vary 
considerably, leading to a high degree of uncertainty. Asbestos exposure without 
asbestosis and smoking increases the risk of lung cancer. The joint effect of 
asbestos and smoking is supra-additive, which may depend in part on the presence 
of asbestosis. Asbestos workers who cease smoking experience a dramatic drop in 
lung cancer risk, which approaches that of nonsmokers after 30 years. Studies to 
date show that longer, thinner fibers have a stronger association with lung 
cancer than shorter, less thin fibers, but the latter nonetheless also show an 
association with lung cancer and mesothelioma. Low-dose chest computed 
tomographic scanning offers an unprecedented opportunity to detect early-stage 
lung cancers in asbestos-exposed workers.