Background: Occupational exposure to asbestos is responsible for 80% at least of all mesothelioma in developed countries. In France there are important regional differences in the rate of mesothelioma compensated as occupational diseases, without knowing if these differences could be explained by a real difference of risk. The objective here is to quantify these regional differences in relation with the differences of level of risk.
Methods: The analysis compares, for each of the 16 regions of the national social security system, mortality for both genders and among men by pleural cancer (ICD 163) in the general population and mesothelioma compensated as occupational diseases during the 1986-1993 period. We computed for each region the number of expected compensated mesothelioma under the hypothesis where the regional distributions of compensated mesothelioma and mesothelioma deaths are the same; as well as the percentage of compensated mesothelioma compared to the deaths, and the variation from the national mean under two hypotheses, high and low; and the probability that a mesothelioma is compensated as an occupational disease taking as a reference the "best" region.
Results: The compensation rate differed significantly among regions (p < 0.05) and for men, the rate between observed and expected numbers of compensated mesothelioma varied from 0.15 (region of Montpellier) to 2.29 (region of Nantes), a ratio over 15. For all of France, the compensation rate was 25% under the best hypothesis. The region of Nantes compensated 61.5% of the male mesothelioma as occupational diseases, while the region of Montpellier and Clermont-Ferrand only around 5%. The probability for a mesothelioma to be compensated, compared to the region of Nantes, was 2.5 times less in national average, and about 10 times less in Montpellier and Clermont-Ferrand regions.
Conclusion: In spite of limits linked to the imprecision of the available data, important regional differences in term of compensation of mesothelioma as occupational diseases clearly exist. Indications lead to think that their origin lies essentially in differences between physicians when considering the occupational etiology of mesothelioma, but differences within the system of compensation of occupational diseases can not be excluded. An improvement of the national statistical system concerning occupational diseases is highly recommendable.