Rapid Fire Australian Epidemiology Association ASM 2018

Lung cancer from occupational low-dose mixed asbestos fibre exposure (#147)

NITA SODHI 1 , Nicholas de Klerk 2 , Peter Franklin 1 , Alison Reid 3 , Fraser Brims 3 4 , Susan Peters 5 , Nola Olsen 1 , Arthur W Musk 1
  1. The University of Western Australia, Nedlands, WESTERN AUSTRALIA, Australia
  2. Telethon Kids Institute, Perth, Western Australaia, Australia
  3. Curtin University, Bentley, Western Australia, Australia
  4. Respiratory Medicine, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
  5. Utretch University, Utretch, The Netherlands

Background: The potential of low-dose exposure to mixed asbestos fibres to cause lung cancer is not well understood.

Method: A cohort of 1,848 men (mean age=62 years; 26% with radiographic asbestosis) occupationally exposed to low-dose mixed asbestos fibres in Western Australia was followed-up from 1990 to 2014 to ascertain their risk of lung cancer. Mixed-effects Poisson regression models were fitted to identify the effect of cumulative asbestos exposure (assessed using the AsbJEM (van Oyen et al., 2015)) after adjusting for sex and time-varying confounding from age, smoking and radiographic asbestosis.

Results: Sixty cases (3.3%) of lung cancer developed during the study period. There was no significant exposure-response relationship between cumulative asbestos exposure and lung cancer after adjusting for age, smoking and radiographic asbestosis (RR=0.81 per unit increase in log of cumulative exposure, 95%CI=0.53-1.21). Men with asbestosis had higher rates of lung cancer (RR=2.36, 95%CI=1.38-4.03) than men without and there was a significant effect of asbestos exposure on the occurrence of asbestosis (RR=1.18 per unit increase in log of cumulative exposure, 95%CI=1.02-1.36).

Conclusion: Our data shows little evidence that low-dose mixed fibre asbestos exposure increases the risk of lung cancer, although radiographic asbestosis raises the risk 2.5-fold. This may be due to the small number of cases coupled with the comparatively low exposures, the lack of discrimination of our exposure assessment tool at these low doses, and the fairly shallow exposure-response relationship between asbestos and lung cancer, all leading  to a dilution of the true dose-response effect.

  1. van Oyen, S. C., et al. (2015). "Development of a Job-Exposure Matrix (AsbJEM) to Estimate Occupational Exposure to Asbestos in Australia." Annals of Occupational Hygiene 59(6): 737-748. doi:10.1093/annhyg/mev017