Age and sex differences in malignant mesothelioma after residential exposure to blue asbestos (Crocidolite)

Background: Blue asbestos was mined and milled at Wittenoom, Western Australia, from 1943 until 1966. Various public records were used to establish a cohort of residents of the nearby township. Mine tailings were distributed throughout the town. Aims: To report the incident number of malignant mesotheliomas that have occurred in residents of the town who did not work at the mine or mill; and to determine if female subjects are more susceptible to asbestos exposure than male subjects, and if children are more susceptible than adults. Subjects and methods: A total of 4,768 residents of the town of Wittenoom have been followed up in cancer and death registries. Results: There were 67 cases of mesothelioma, and 64 deaths with mesothelioma to the end of 2002. The mortality rate with mesothelioma increased with increasing residence duration, time since first exposure, and estimated cumulative exposure. The mesothelioma mortality rate was consistently lower for female subjects when compared with male subjects, but the dose-response curve was steeper for female subjects. The rate was lower in those first exposed as children compared with those first exposed at >= 15 years of age. The dose-response slope for asbestos exposure and mortality from mesothelioma was not different between those who were first exposed as children than those who were first exposed at >= 15 years of age. Conclusions: Former residents of a crocidolite, mining town have a high rate of mesothelioma. The rate is higher in male subjects and those >= 15 years of age at first exposure, but women have a steeper dose-response curve.