Estimation de l’impact sanitaire associé à l’exposition au formaldéhyde dans les environnements intérieursImpact sanitaire du formaldéhyde dans les environnements intérieurs

Because of its many applications permitted by its physical and chemical properties, formaldehyde is an ubiquitous substance in indoor environments. In 2004, the International Agency for Research on Cancer classified it as carcinogenic to humans (group 1). This study, intended to assess the health impact of indoor exposure to formaldehyde, was conducted as part of a study of the socioeconomic costs of indoor air pollution. Four health effects-asthma, sensory irritation, histopathological lesions of the nasal cavity, and nasopharyngeal carcinoma-were identified as results of chronic exposure to inhalation of formaldehyde. A key source study was selected for each effect, from which dose-response relations were constructed or selected. At the same time, we established exposure scenarios for the French population by taking into account the variability of the frequency of residence in the different environments according to age group and socioeconomic status. These scenarios enabled us to obtain distributions of inhaled concentrations, which we crossed with dose-response relations to calculate the health impact for each effect. From a methodological point of view, the calculation of the health impact used an original approach in this context: a probabilistic approach for effects with a mode of action with a threshold. Moreover, different health effects were taken into account for the same substance; we also considered the variability of adjustment factors, relative risks, and odds ratios. From a health point of view, this study concludes that the risk of developing nasopharyngeal cancer among the general population appears negligible, but that the health impact of asthma among children aged from 0 to 18 years must be considered.