Human exposure to endocrine disruptors via ambient air: An unknown health risk
Résumé
Purpose of the study. Human activities involve the occurrence in ambient air of a multitude of semi-volatile organic compounds (SVOC) acting as endocrine disruptors (ED). These are released into the air by combustion processes and/or passive volatilization at ambient temperature. Multi-residue air contamination by xenobiotic compounds was poorly documented by few international studies, despite the existence of many potential emission sources of plasticizers, surfactants, persistent organic pollutants, flame retardants or bactericides. In terms of sanitary risk assessment, the respiratory tract was considered to be negligible as compared to the digestive one. However, inhalation may cause differences in chemical impregnation according to individuals. In that context, the main objective of our work was to achieve a better understanding of ED transfer from air, whether indoor or outdoor, towards man and to evaluate in parallel, the respective importance of the hazards from their inhalation via gaseous and/or particulate phases. Methods. The study of gaseous and particulate phase contamination in ambient air focused on 58 organic molecules from industrial synthesis: plasticizers (phthalates and bisphenol A - BPA), flame retardants (PBDEs and TBBPA), surfactants (alkylphenols), bactericides (parabens), organochlorine compounds (PCBs/HCB/PeCB), polycyclic aromatic hydrocarbons (PAHs). Their identification and quantification were performed using a ``large volume'' dynamic air sampling, then the analysis of gas phase and particulate phase separately by gas or liquid chromatographic techniques coupled with mass spectrometry. Exposure to ED compounds was assessed in three outdoor sites: city (Paris), suburban (Lognes 94), forest of Fontainebleau (77) and in three indoor sites with different occupations and equipments (a flat, an office, a day nursery). Two-week integrated sampling was carried out during two consecutive thermally contrasted periods summer/winter (2010/2011) and autumn/winter (2011/2012). Results. All investigated ED were found in all studied sites and could almost always be quantified at concentrations ranging from 0.1 to 100 ng/m(3). The main ED, indoors as well as outdoors, were plasticizers from the phthalate chemical group, with concentrations up to 1 mu g/m(3). By decreasing order, came alkylphenols: 50 ng/m(3), parabens: 1 to a few ng/m(3), PAHs: 0.5 and 1 ng/m(3) and PCBs: 0.35 to 1.8 ng/m(3). BPA was close to the threshold of 1 ng/m(3). The concentrations of flame retardants of the PBDE group were lower and did not exceed 0.1 ng/m(3) and TBBPA was generally below this value, corresponding to the limit of quantification. The comparison of indoor concentrations with urban background concentrations showed that all contaminants had indoor concentrations from 10 to 80 times higher than outdoor air, except PAHs and BPA. The gas phase was still dominant for most molecules, except for very poorly volatile compounds, such as BaP and DEHP. However in summer, DEHP was mainly present in the gas phase. Alkylphenols, phthalates, PCBs and parabens were present for more than 90% in the gas phase of indoor air. Their proportion outdoors in the gas phase was less important but still remained dominant, although it tended to decrease in winter, especially PAHs mainly emitted during combustion processes. Conclusion. ED compounds are ubiquitous in the air of all premises, with concentrations in indoor air almost always higher than in outdoor air, due to confinement, human activities and potential sources that will be specified. Moreover, contrary to common opinion about the relatively low vapor pressure of SVOC, it appears here as well as in other works abroad, that human exposure to most compounds arises mainly from the gas phase rather than inhalation or ingestion of particulate aerosols. (C) 2013 Elsevier Masson SAS. All rights reserved.