Risk of mesothelioma from exposure to crocidolite asbestos: a 1995 update of a South African mortality study

Abstract

person-years, respectively. The mortality for lung cancer (29 deaths) was 287 (135-436) per 10 6 person-years, and that for other non-respiratory cancers (60 deaths) was 593 (442-745). Two cases of laryngeal and four of colon cancer were observed. All cancer mortality, mesothelioma, and lung cancer proportional cancer mortality ratios were increased. Conclusion-The mortality for mesothelioma in men was twice that in women, probably because men were more likely to have had both occupational and environmental exposure to asbestos. Nevertheless, the mortality in women was still high and is probably indicative of the environmental exposure as white women were rarely employed in the asbestos industry in the Prieska area. Due to the long latency from first exposure to diagnosis of the neoplasm, the cause specific mortality in this cohort could be expected to increase rapidly over the next 10 years.

Mineralogy and Malignant Mesothelioma: The South African Experience

“…The average annual mortality rates for mesothelioma determined from two cohort studies in the region was 85 per million per year during 1977-83 and 178 per million per year during 1987-95. The latter rate is lower but in the same order as the rate of 277 per million person-years (95% CI 170-384) found for mesothelioma in the mortality study of the birth cohort in the South African crocidolite mining district of Prieska (Kielkowski et al, 2000). Age-standardised mesothelioma incidence has been reported for past residents of Wittenoom without occupational exposure to asbestos (Hansen et al, 1998).…”

“…In a review of 504 cases from four of the above studies (White et al, 2008), the exposure was attributed to the environment in 23% in total. The 1973 Webster and1984 Solomons studies are probably the least reliable in terms of proportions of environmentally-induced cases; if these two are ignored the remaining studies are fairly consistent: in South African mining regions the proportion of environmental cases is in the order of 29% (Kielkowski et al, 2000;Mothemela, 2011) and between 16% and 19% for the country as a whole (Zwi et al, 1989;Rees et al, 1999a;Cochrane and Webster, 1978).…”

“…It is likely that thorough interrogation for (Solomons, 1984), whereas the cases were collected from 1955-1970. The Kielkowski study (Kielkowski et al, 2000) did not have exposure data, but assumed environmental exposure in all women subjects; if even a small proportion had had occupational exposure the 29% proportion would be reduced. The Mothemela data (Mothemela, 2011) are not generalisable to the country as a whole as these data are from claimants who either lived near or worked at mining operations.…”

“…A birth cohort was established in one of the magisterial districts in which the above study was conducted (Reid et al, 1990;Kielkowski et al, 2000). The cohort comprised men and women whose births were registered from 1916 to 1936.…”

Assessment of cancer risks due to environmental exposure to asbestos

“…In the Republic of South Africa several regions around asbestos mines have been heavily polluted and epidemiological studies have shown that regional MM mortality rates were twice as high in men as well as in women as compared with national mortality rates, whereby especially the high mortality among women was indicative for environmental exposure (Reid et al, 1990;Kielkowski et al, 2000;Braun and Kisting, 2006). Abratt et al (2005) have estimated that in South Africa approximately 26% of all MM cases can be attributed to environmental asbestos exposure.…”