Occupational and environmental mesotheliomas due to crocidolite mining activities in Wittenoom, Western Australia.

OBJECTIVES

The aim of the study was to review existing cases, calculate rates, and predict future numbers of occupational and environmental mesotheliomas from Wittenoom.

METHODS

On the basis of information contained in occupational and environmental histories, Wittenoom cases were extracted from national records collected since 1979. Occupational and residential population estimates were obtained from company and government records. The proportional latency method was used to predict the numbers of mesotheliomas prior to and after the data collection phase. Airborne fiber monitoring was used to calculate risk due to current levels of contamination in the mine and town environments.

RESULTS

During 1979-1994, Wittenoom cases (N = 176) comprised approximately 6% of the mesothelioma cases recorded in Australia. Of these 122 were employed directly in the mining and milling activities, another 18 were involved in the transport of raw fiber or tailings, and 34 were town residents or visitors. Due to past exposures, additional occupational (N = 301) and environmental (N = 83) cases can be expected. Dependent on residential time, existing levels of contamination may result in a risk of between < 1 to 57 per million of the population.

CONCLUSIONS

Latency effects will result in considerable numbers of mesotheliomas appearing over the next 10-20 years in Wittenoom. The cessation of mining activities and major clean up of the town will result in reduced mesothelioma cases.