Pleural mesothelioma in New Caledonia: associations with environmental risk factors

Our plain-English summary of Pleural mesothelioma in New Caledonia: associations with environmental risk factors, by F. Baumann, P. Maurizot, M. Mangeas, et al (Environmental Health Perspectives, 2011).

The study

• Authors: F. Baumann, P. Maurizot, M. Mangeas, J.P. Ambrosi, J. Douwes, B. Robineau
• Journal: Environmental Health Perspectives
• Published: 2011;119(5):695-700
• Cited by: 56 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

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.

In plain English

This ecological study examined malignant pleural mesothelioma in New Caledonia. The authors analyzed 104 of 109 histologically confirmed registry cases diagnosed 1984 to 2008. They searched for clusters and compared environmental features around 100 tribal communities (82 analysis units), including serpentinite on roads, quarries, mining and whitewash. Age-standardized incidence was highest in Houaïlou (128.66 per 100,000 person-years; 95% CI 70.41 to 137.84) versus 0.64 (95% CI 0.13 to 1.88) in Noumea. One significant cluster of 18 tribes had 31 cases where 8.12 were expected; no significant cluster in time was found. Serpentinite on roads showed the strongest association. Comparing tribes with and without cases, it was the only factor in the final logistic model (odds ratio 465.0; 95% CI 46.2 to 4679.7). In a Poisson model with other factors, its incidence rate ratio was 13.052 (95% CI 10.225 to 16.661). Antigorite was more strongly associated than tremolite-actinolite; whitewash use was not a significant risk factor. The authors concluded that serpentinite road surfacing is a major environmental risk factor for mesothelioma in New Caledonia; they noted occupational exposure could not be assessed.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Ecological study comparing tribes with and without mesothelioma cases, plus spatial, temporal and space-time cluster analyses of registry cases
• Who was studied: Histologically confirmed malignant pleural mesothelioma cases in the Cancer Registry of New Caledonia, diagnosed 1984 to 2008. There were 109 eligible cases and 104 were analyzed: 49 men and 55 women, 91 of them Melanesian. Five were excluded for having lived in New Caledonia under 20 years. The ecological analysis covered 100 tribes in a study area that included the communes with the highest incidence. After small tribes were grouped, there were 82 geographical units: 34 with cases and 48 without.
• Exposure: Natural sources of asbestos near each tribe. These were serpentinite on roads, serpentinite outcrops and quarries, antigorite, chrysotile and tremolite-actinolite, distance to the peridotite massif, an index of nickel mining activity, and whitewash (Pö) that could contain tremolite. Vegetation, slope and distance to the coast were also examined.
• Main results:
  • The world age-standardized incidence was 128.66 per 100,000 person-years in Houaïlou (95% CI 70.41 to 137.84), compared with 0.64 (95% CI 0.13 to 1.88) in Noumea.
  • One significant spatial cluster of 18 tribes in the Houaïlou-Bourail area had 31 observed cases versus 8.12 expected (p = 0.001). Two secondary clusters, in Koné and Poindimié, were not significant.
  • No significant temporal cluster was found. A space-time cluster of 14 tribes in the Houaïlou area for 1991 to 2003 had 18 observed versus 3.10 expected cases (p = 0.001).
  • Serpentinite on roads was present among 97% of tribes with mesothelioma cases versus 6% of tribes without cases.
  • In the backward stepwise logistic regression comparing tribes with and without cases, serpentinite on roads was the only factor in the final model. It gave OR = 465.0 (95% CI 46.2 to 4679.7) and explained 72% of the total variance.
  • In the multivariate Poisson regression, which also included other environmental and protective factors, serpentinite on roads gave an incidence rate ratio of 13.052 (95% CI 10.225 to 16.661).
  • In univariate analysis, antigorite (a serpentine) was much more strongly associated with mesothelioma, OR = 20.667 (95% CI 4.028 to 106.03), than tremolite-actinolite (an amphibole), OR = 1.714 (95% CI 0.664 to 4.423).
  • Use of whitewash did not emerge as a significant risk factor for mesothelioma.
  • The mining activity index showed only a very small effect, while proximity to the peridotite massifs was significantly associated with mesothelioma.
  • Living on a slope over 10 degrees appeared protective. Living around dense vegetation also appeared protective, but this was not statistically significant.
• The authors' conclusion: The authors concluded that their study provides strong evidence that using serpentinite for road surfacing is a major environmental risk factor for mesothelioma in New Caledonia.
• Limitations the authors state:
  • Information on occupation was insufficient to assess the role of occupational exposure. The authors argued that residual confounding by occupation is not likely to explain the results.
  • Because of the long latency period and the involuntary nature of environmental exposure, personal exposure is difficult to reconstruct. Exposures were measured at the tribe level, not for individuals.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile, Mesothelioma.

Medical terms in this study, explained in our Lexicon: Pleural Mesothelioma, New Caledonia, Malignant Mesothelioma, Serpentinite, Cancer Registry, Incidence, confidence interval, Odds Ratio.

Related studies

• Pleural mesothelioma in New Caledonia: an acute environmental concern — F. Baumann, Y. Rougier, et al. (2007)
• Assessment of environmental and domestic exposure to tremolite in New Caledonia — D. Luce, M.A. Billon-Galland, et al. (2004)
• Occupational and environmental risk factors for idiopathic pulmonary fibrosis in Australia: case-control study — M.J. Abramson, T. Murambadoro, et al. (2020)
• Toward Understanding of Environmental Risk Factors in Systemic Sclerosis — L. Ouchene, A. Muntyanu, et al. (2021)
• Indigenous health and environmental risk factors: an Australian problem with global analogues? — L.D. Knibbs, P.D. Sly (2014)
• Environmental exposure to tremolite and respiratory cancer in New Caledonia: a case-control study — D. Luce, I. Bugel, et al. (2000)

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