Comments on the causation of malignant mesothelioma: rebutting the false concept that recent exposures to asbestos do not contribute to causation of mesothelioma

BACKGROUND European asbestos manufacturers and their expert witnesses have advanced the claim that recent exposures to asbestos are not of significance in the causation of malignant mesothelioma. They argue that in cases of prolonged exposure to asbestos only the earliest exposures contribute to mesothelioma induction. METHODS The Collegium Ramazzini examined this claim and compared it with the findings of the Epidemiology and Public Health Working Group of the Second Italian Consensus Conference on Pleural Mesothelioma. This independent Working Group noted that earlier exposures are more effective in inducing mesothelioma, but that subsequent exposures also contribute and cannot be excluded. They found convincing evidence to support the conclusion that mesothelioma incidence is proportional to cumulative asbestos exposure. CONCLUSION The Collegium Ramazzini concludes that risk of malignant mesothelioma is proportional to cumulative exposure to asbestos in which all exposures - early as well as late - contribute to the totality of risk. The Collegium Ramazzini rejects as false and scientifically unfounded the notion that only the earliest exposures to asbestos contribute to mesothelioma induction.