Pleural Mesothelioma in New Caledonia: Associations with Environmental Risk Factors

Article excerpt

BACKGROUND: High incidences of malignant mesothelioma (MM) have been observed in New Caledonia. Previous work has shown an association between MM and soil containing serpentinite.

OBJECTIVES: We studied the spatial and temporal variation of MM and its association with environmental factors.

METHODS: We investigated the 109 MM cases recorded in the Cancer Registry of New Caledonia between 1984 and 2008 and performed spatial, temporal, and space-time cluster analyses. We conducted an ecological analysis involving 100 tribes over a large area including those with the highest incidence rates. Associations with environmental factors were assessed using logistic and Poisson regression analyses.

RESULTS: The highest incidence was observed in the Houailou area with a world age-standardized rate of 128.7 per 100,000 person-years [95% confidence interval (CI), 70.41-137.84]. A significant spatial cluster grouped 18 tribes (31 observed cases vs. 8 expected cases; p = 0.001), but no significant temporal clusters were identified. The ecological analyses identified serpentinite on roads as the greatest environmental risk factor (odds ratio = 495.0; 95% CI, 46.2-4679-7; multivariate incidence rate ratio = 13.0; 95% CI, 10.2-16.6). The risk increased with serpentinite surface, proximity to serpentinite quarries and distance to the peridotite massif. The association with serpentines was stronger than with amphiboles. Living on a slope and close to dense vegetation appeared protective. The use of whitewash, previously suggested to be a risk factor, was not associated with MM incidence.

CONCLUSIONS: Presence of serpentinite on roads is a major environmental risk factor for mesothelioma in New Caledonia.

KEY WORDS: antigorite, asbestos, cluster analysis, ecological study, environment, mesothelioma, New Caledonia, serpentinite. Environ Health Perspect 119:695-700 (2011). doi:10.1289/ehp.1002862 [Online 30 December 2010]

Malignant mesothelioma (MM) is a rare and fatal tumor of the pleura, with a worldwide annual incidence of one or two cases per million inhabitants. The incidence has increased since the 1950s among men in regions where asbestos was mined or industrially used (MacDonald and MacDonald 1986). Inhalation of asbestos fibers is the only established causal factor for MM (Merler and Chellini 1992). MM may also occur after exposure to erionite fibers (Baris et al. 1979), or fluoroedcnite fibers (Putzu et al. 2006). The risk of MM increases with level and duration of exposure (Cugell and Kamp 2004), with a median latency period of 30-40 years (Montanaro et al. 2003). Incidence fates have been reported to be 1.2-9 times higher among men than among women because of occupational exposure (Ross and McDonald 1995).

MM has been associated with domestic exposure in family members of asbestos workers (Ferrante et al. 2007) and with environmental exposure (Hillerdal 1999; Maule et al. 2007) related to asbestos factories, mines, or naturally occurring asbestos in Greece (Constantopoulos et al. 1987), Cyprus (McConnochie et al. 1987), Turkey (Carbone et al. 2007), Corsica (Rey et al. 1993), Italy (Magnani et al. 2001), and the United States [California (Pan et al. 2005)].

There are two main families of asbestos: amphiboles (tremolite, actinolite, crocidolite) and serpentines (chrysorile, antigorite, lizard-ite). Asbestos fibers vary in length and shape: chrysotile has long, flexible fibers, whereas amphiboles fibers are brittle. Although all types of asbestos fibers can be associated with MM, the highest risks have been reported for amphiboles (Hodgson and Darnton 2000). Health problems associated with exposure to airborne asbestos particles have resulted in severe restrictions on the use of asbestos from the 1980s. In natural environments, asbestos is commonly associated with ultramafic rocks (rich in iron and magnesium minerals), mostly peridotites, of which hydration produces serpentinites (Schreier 1989). …