Pleural mesothelioma in New Caledonia: an acute environmental concern

Our plain-English summary of Pleural mesothelioma in New Caledonia: an acute environmental concern, by F. Baumann, Y. Rougier, J.P. Ambrosi, et al (Cancer Detection and Prevention, 2007).

The study

• Authors: F. Baumann, Y. Rougier, J.P. Ambrosi, B.P. Robineau
• Journal: Cancer Detection and Prevention
• Published: 2007;31(1):70-6
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

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.

In plain English

This case-control study asked whether Pö, a lime used to cover house walls, was the only cause of pleural mesothelioma in New Caledonia. The authors took 68 histologically confirmed cases diagnosed from 1984 to 2002 from the Cancer Registry (37 men, 31 women). Controls were 136 registry patients with other cancers, matched by gender, age and diagnosis date. Of the cases, 61 (89.7%) were Melanesian; compared with Caucasians, Melanesians had an odds ratio of 16.18 (95% CI 5.68 to 49.64). About 30% of cases lived around Houailou. Across districts, mining activity was not associated with mesothelioma. On Pö the article is inconsistent: the Results report no significant relationship, while the Discussion says univariate linear regression showed one; Pö was not significant in multivariate analysis. Soil serpentinite was associated with mesothelioma in linear regression, univariate (p = 0.017) and multivariate (p = 0.067, within the authors' 0.10 threshold), but not significantly in multivariate logistic regression. The authors concluded that only soil serpentinite was identified as a significant risk factor and that mesothelioma is multifactorial in New Caledonia. They noted that mining-sector occupational activities were not considered.

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: Retrospective case-control study using cancer-registry controls, combined with a district-level comparison (logistic and linear regression) of districts with and without mesothelioma cases
• Who was studied: 68 histologically confirmed pleural mesothelioma cases (37 men, 31 women, aged 31 to 81), out of 89 pleural malignant cancers recorded in the Cancer Registry of New Caledonia, 1984 to 2002. Also 136 controls (74 men, 62 women) with cancers at sites other than the pleura, peritoneum or lung.
• Exposure: District-level environmental factors: the number of dwellings covered with Pö (a traditional lime used on house walls), the level of mining activity (major or minor), and a grade for serpentinite in surface soil based on whether it lay within 5 km of dwellings. Ethnic group and place of residence were also compared.
• Main results:
  • Melanesians had an odds ratio of 16.18 (95% CI 5.68 to 49.64), with Caucasians as the reference group.
  • 61 of the 68 cases (89.7%) were Melanesian, with an age-adjusted incidence of 7.52 per 100,000 per year. 5 cases were Caucasian, with an incidence of 0.57.
  • About 30% of cases, all Melanesian, lived in the Houailou area. Residence there had an odds ratio of 119 (95% CI 34 to 502) compared with Noumea.
  • In the Results section, the authors state that neither logistic nor linear regression comparing districts showed a significant relationship between Pö and mesothelioma.
  • In the Discussion, the authors state that univariate linear regression did show a relationship between Pö and mesothelioma (Table 3: p = 0.061, against the 0.10 threshold chosen for the district analysis). Pö was not significant in multivariate analysis. The authors suggest the relationship between Pö and serpentinite (p = 0.022) could explain this univariate result.
  • No relationship was found between mining activity and mesothelioma.
  • In univariate linear regression, serpentinite in the soil was significantly associated with mesothelioma (p = 0.017). In univariate logistic regression the odds ratio was 2.61 (95% CI 0.96 to 7.15).
  • Multivariate linear regression showed a relationship between serpentinite and mesothelioma (p = 0.067), which the authors called significant under the 0.10 threshold they chose for the district analysis.
  • Multivariate logistic regression showed no significant association. The odds ratio for serpentinite comparing districts with and without cases was 2.49 (95% CI 0.82 to 7.58).
  • 17 cases were under age 50. All Caucasian cases were men over 60. The Melanesian sex ratio was 1.03.
• The authors' conclusion: The authors concluded that, in multivariate analysis, only serpentinite in the soil of the place of residence was identified as a significant risk factor, that Pö did not explain all cases, and that mesothelioma is a multifactorial problem in New Caledonia.
• Limitations the authors state:
  • Cancer-registry controls do not exactly represent the population of New Caledonia; Caucasians are somewhat over-represented.
  • The registration of Pö-covered houses may be incomplete. On-site optical microscopy could not tell fiber types apart (such as chrysotile or tremolite) and could have missed very small fibres.
  • Current place of residence was used despite the long latency, so some subjects may have been assigned to Noumea rather than to the tribal district where they could have been exposed.
  • Incidences by district were underestimated: place of residence was unknown for 11 of the 68 cases, and cases far from care centers may not have been diagnosed.
  • The serpentinite assessment was limited by the precision of geological maps.
  • Not all risk factors could be considered; in particular, occupational activities in the mining sector were not considered.

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, Mesothelioma, Cancer Registry, Serpentinite, Environmental Exposure, Occupational Exposure.

Related studies

• Pleural mesothelioma in New Caledonia: associations with environmental risk factors — F. Baumann, P. Maurizot, et al. (2011)
• Assessment of environmental and domestic exposure to tremolite in New Caledonia — D. Luce, M.A. Billon-Galland, et al. (2004)
• The relationship between malignant mesothelioma and an asbestos cement plant environmental risk: a spatial case-control study in the city of Bari (Italy) — M. Musti, A. Pollice, et al. (2009)
• Environmental risk of mesothelioma in the United States: An emerging concern-epidemiological issues — F. Baumann, M. Carbone (2016)
• Environmental exposure to tremolite and respiratory cancer in New Caledonia: a case-control study — D. Luce, I. Bugel, et al. (2000)
• Oxidative status and acute phase reactants in patients with environmental asbestos exposure and mesothelioma — C. Sezgi, M. Taylan, et al. (2014)

Browse return to medical research.