A new study has found that non-occupational exposure to asbestos was the main cause of malignant mesothelioma, in the female population of North Jutland, Denmark, and may account for up to 66% of cases among women.[i]
The researchers analysed cell samples of women diagnosed with malignant mesothelioma, between 1974 and 2015, from a hospital in Denmark. The North Jutland region has a history of asbestos use in a major cement product factory and a large shipyard.
Asbestos exposure was classified by type:
- ‘occupational’, for those who worked with asbestos;
- ‘domestic’, for those who shared a residence with an asbestos worker;
- ‘environmental’, defined as living or working within 10 km of either the factory or the shipyard; or
- ‘unknown’, where no source of asbestos exposure could be identified.
The number of cases of malignant mesothelioma was determined, and the overall relative risk among women was calculated.
Among 91 women diagnosed with mesothelioma, exposure type was as follows:
- ‘occupational’ – 9% of cases;
- ‘domestic’ – 10% of cases;
- ‘environmental’ – 22% of cases;
- ‘domestic’ and ‘environmental’ in combination – 34% of cases; and
- ‘unknown’ – 25% of cases.
One year of ‘environmental’ exposure was significant for an association with malignant mesothelioma. Women with ‘secondary exposure’ to asbestos tended to develop pleural mesothelioma and women with ‘occupational’ exposure tended to develop peritoneal mesothelioma, but no definitive conclusions could be drawn in respect of this association. Overall, the median time since first asbestos exposure was 61.5 years, with a range of 11 to 95 years.
In a ‘hotspot’ of parishes surrounding the asbestos-consuming industries in Aalborg, the maximum relative risk of developing mesothelioma was found the parish where the cement products factory was located.
A limitation of this study is that there was limited (or no) data on the occupational history of some study participants and relatives prior to 1964. What is more, not all residence and address details were complete. The effect of this could be that some of the cases classified as being caused by ‘environmental’ exposure could have been due in part, or in full, to ‘occupational’ or ‘domestic’ exposure. There could also have been undocumented asbestos exposure arising out of damaged asbestos materials in buildings, for example.
Nevertheless, this study adds to the evidence that ‘environmental’ exposure alone is sufficient to increase the risk of mesothelioma. It also adds to evidence which suggests that some cases of mesothelioma do not appear to be associated with asbestos exposure.
[i] Panou, V. et al. Non-occupational exposure to asbestos is the main cause of malignant mesothelioma in women in North Jutland, Denmark. Scandinavian Journal of Work, Environment & Health doi:10.5271/sjweh.3756 http://www.sjweh.fi/show_abstract.php?abstract_id=3756 (Accessed 2 August 2018).