Pleural mesothelioma in New Caledonia: associations with environmental risk factors.

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 Houaïlou 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.

Pleural mesothelioma in New Caledonia: an acute environmental concern.

BACKGROUND: In 1991, a relationship was established between excess cases of pleural cancer in New Caledonia and a traditional lime, called "Pö", to cover houses. Our study aimed to determine whether the Pö is the only cause of mesothelioma in New Caledonia. METHODS: Eligible cases were pleural tumor diagnosed between 1984 and 2002 with histological diagnosis of mesothelioma. For each case, two controls were selected from the cancer registry. Cases and controls were compared for the ethnic groups and the places of residence. To identify environmental risk factors, we used first a qualitative analysis comparing villages with and without mesothelioma cases, then a linear regression including Pö, mining activity and serpentinite in surface soil. RESULTS: Sixty-eight cases were included: 37 men and 31 women. Melanesians had the highest risk (OR=16.18; 95% CI=[5.68; 49.64]) and 30% of the cases lived in Houailou (OR=119). Mining activity and Pö were not significant risk factors. The existence of a significant relationship between soil containing serpentinite and mesothelioma was demonstrated (p=0.017). The sex ratio close to 1 and the number of young cases are consistent with environmental exposure. CONCLUSION: Pö did not explain all cases; only serpentinite in the soil was identified as a significant risk factor. A research project has been initiated in the area around Houailou, with the objective of constructing a model taking into account: exposure to the Pö, exposure to airborne pollution by asbestos fibres at the place of residence, and occupational exposure. Epidemiological and geological investigations are underway.