Environmental exposure to tremolite and respiratory cancer in New Caledonia: a case-control study

Our plain-English summary of Environmental exposure to tremolite and respiratory cancer in New Caledonia: a case-control study, by D. Luce, I. Bugel, P. Goldberg, et al (American Journal of Epidemiology, 2000).

The study

• Authors: D. Luce, I. Bugel, P. Goldberg, M. Goldberg, C. Salomon, M.A. Billon-Galland, J. Nicolau, P. Quénel, J. Fevotte, P. Brochard
• Journal: American Journal of Epidemiology
• Published: 2000;151(3):259-65
• Cited by: 55 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

A case-control study on respiratory cancers was conducted in New Caledonia (South Pacific), where a high incidence of malignant pleural mesothelioma had been observed. The disease pattern suggested an environmental exposure to asbestos. The first results showed that, in some areas, tremolite asbestos derived from local outcroppings was used as whitewash (locally named "pö"). All cases diagnosed between 1993 and 1995 (including 15 pleural mesotheliomas, 228 lung cancers, and 23 laryngeal cancers) and 305 controls were included in the study. Detailed information on past or present use of the whitewash, residential history, smoking, diet, and occupation was collected. The risk of mesothelioma was strongly associated with the use of the whitewash (odds ratio (OR) = 40.9; 95% confidence interval (CI): 5.15, 325). All Melanesian cases had been exposed. Among Melanesian women, exposure to the whitewash was associated with an increased risk of lung cancer (OR = 4.89; 95% CI: 1.13, 21.2), and smokers exposed to po had an approximately ninefold risk (OR = 9.26; 95% CI: 1.72, 49.7) compared with women who never smoked and had never used the whitewash. In contrast, no association was noted between exposure to pö and lung cancer risk among Melanesian men, probably because of lower exposure levels. Among non-Melanesians, the numbers of exposed subjects were too small to assess the effect of exposure to po. There was no indication of elevated risks for the other cancer sites.

In plain English

This population-based case-control study in New Caledonia (South Pacific) examined a local whitewash called "pö". Samples of the rock and the whitewash consisted of virtually pure tremolite asbestos. The study compared 273 respiratory cancer cases diagnosed from 1993 to 1995 with 305 randomly selected population controls. The cases included 228 lung cancers, 23 laryngeal cancers and 15 pleural mesotheliomas. Exposure meant living in a whitewashed house or preparing and applying the whitewash. Of 15 pleural mesothelioma cases, 14 reported exposure; the odds ratio for ever exposed was 40.9 (95% confidence interval 5.15 to 325). Among Melanesian women, exposure was associated with lung cancer (odds ratio 4.89, 1.13 to 21.2). Exposed Melanesian women who smoked had an odds ratio of 9.26 (1.72 to 49.7) versus Melanesian women who neither smoked nor used the whitewash. No association with lung cancer was seen in men, nor any sign of raised laryngeal cancer risk. The authors concluded that the whitewash strongly increased mesothelioma risk and was linked to lung cancer in women only, probably because men had lower exposure. They noted that exposure was self-reported.

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: Population-based case-control study, analysed with unconditional logistic regression
• Who was studied: 273 cases from the Cancer Registry of New Caledonia, diagnosed January 1993 to December 1995: 228 lung, 23 larynx, 5 hypopharynx and 1 sinonasal cancer, 15 pleural mesotheliomas (9 definite, 6 possible) and 1 peritoneal mesothelioma. Cases were over 18 years old and had lived in New Caledonia for at least 5 years. There were 305 population controls, frequency matched by sex and age.
• Exposure: Tremolite asbestos from local outcroppings, used as a whitewash called "pö" on house walls. Exposure was counted from living in a whitewashed house or preparing and applying the whitewash. It was measured as ever exposed, total duration and age at first exposure. Occupational exposure to dust from mines, building sites, roads and fields was also examined.
• Main results:
  • Pleural mesothelioma: all 9 female cases and 5 of 6 male cases reported exposure to pö. The odds ratio for ever exposed (adjusted for age and sex) was 40.9 (95% CI 5.15, 325).
  • Pleural mesothelioma risk rose with duration of exposure: the odds ratio was 22.2 (2.33, 211) for under 20 years and 65.1 (7.69, 551) for 20 years or more.
  • All 14 Melanesian pleural mesothelioma cases had been exposed to pö, compared with 53 percent of Melanesian controls (p less than 0.001).
  • The single peritoneal mesothelioma case was a Melanesian man who prepared the whitewash and had lived all his life in a whitewashed house. Including this case gave an ever-exposed odds ratio of 43.5 (95% CI 5.52, 342).
  • Lung cancer in women: for all women ever exposed, the odds ratio was 2.51 (1.01, 6.22). For Melanesian women ever exposed, it was 4.89 (1.13, 21.2), based on 17 exposed cases and 7 exposed controls.
  • Among Melanesian women, smokers exposed to pö had an odds ratio of 9.26 (1.72, 49.7) compared with non-smokers never exposed. The positive interaction between smoking and pö was not statistically significant.
  • Lung cancer in men: there was no elevated risk with pö exposure. The odds ratio was 0.89 (0.51, 1.54) for all men ever exposed and 0.87 (0.41, 1.85) for Melanesian men.
  • By tumor type among women, the excess lung cancer risk with pö was significant only for squamous cell carcinoma (odds ratio 6.49; 1.31, 32.2). The authors said small numbers meant a similar association for other types could not be ruled out.
  • Among non-Melanesians, the number of exposed subjects was too small to evaluate the effect of pö.
  • Laryngeal cancer (male smokers and ex-smokers): exposure to pö was associated with a non-significantly decreased risk, odds ratio 0.72 (95% CI 0.22, 2.30). Three of 20 male cases and none of 3 female cases had been exposed.
  • Occupational soil dusts in men: apart from a raised lung cancer risk at a low level of building site dust exposure (odds ratio 2.56; 1.02, 6.45), no significant association was found. There was no dose-response trend.
• The authors' conclusion: The authors concluded that use of the tremolite-containing whitewash strongly increased mesothelioma risk and was associated with increased lung cancer risk in women only. They attributed the lack of association in men probably to lower exposure levels. They found no indication of elevated risks for the other respiratory cancer sites.
• Limitations the authors state:
  • Occupational exposures were only categorised as ever or never, and diet only by frequency of consumption, so residual confounding could not be ruled out.
  • Next-of-kin respondents were used for about 25 percent of lung cancer cases but only two controls. The authors reported that reanalysis without these interviews gave similar results.
  • Exposure to pö was self-reported, the composition of the whitewash used could not be verified, and reporting bias could not be excluded.
  • Because there were few mesothelioma cases, the separate effects of age at first exposure and duration of exposure could not be assessed.
  • The occupational dust exposures lacked the specificity needed to stand in for tremolite exposure.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Tremolite.

Medical terms in this study, explained in our Lexicon: Environmental Exposure, Tremolite, New Caledonia, Case-Control Study, Pleural Mesothelioma, Whitewash, Lung Cancer, Laryngeal Cancer.

Related studies

• Assessment of environmental and domestic exposure to tremolite in New Caledonia — D. Luce, M.A. Billon-Galland, et al. (2004)
• Occupational exposures and lung cancer in New Caledonia — G. Menvielle, D. Luce, et al. (2003)
• Environmental mesothelioma associated with tremolite asbestos: lessons from the experiences of Turkey, Greece, Corsica, New Caledonia and Cyprus — S.H. Constantopoulos (2008)
• Malignant pleural mesothelioma associated with exposure to tremolite — D. Luce, P. Brochard, et al. (1994)
• Environmental airborne tremolite asbestos pollution and pleural plaques in Afghanistan — C. Voisin, I. Marin, et al. (1994)
• Investigation of occupational and environmental causes of respiratory cancers (ICARE): a multicenter, population-based case-control study in France — D. Luce, I. Stücker, et al. (2011)

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