Indoor Dust Levels of Perfluoroalkyl Substances (PFASs) and the Role of Ingestion as an Exposure Pathway: A Review

Perfluoroalkyl substances (PFASs) are emerging pollutants whose scientific knowledge has notably increased in the last two decades. Detectable amounts of PFASs, and particularly perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), have been found in the environment, wildlife and humans. Nowadays, the presence of PFASs and its global distribution is well known. However, there is still a high degree of uncertainty in the pathways of exposure through which PFASs enter the human body. Similarly to "classical" persistent organic pollutants (POPs), dietary intake seems to be the predominant exposure route, with water consumption being identified as a potentially important pathway. Since most human exposure to PFASs occurs in indoor environments, the inhalation of indoor air and the ingestion of dust might notably contribute to the total intake of PFASs. In fact, some investigations point out the possibility that, because of higher dust ingestion rates, the PFAS exposure for toddlers could be much higher than that for adults. Even more, the children intake of PFASs could be dominated by dust ingestion, instead of food as the most important exposure pathway. In this paper, we review a number of recent of studies reporting concentrations of PFASs in dust and estimations on the human exposure via dust ingestion. An important geographical variation among countries was observed, therefore indicating that the assessment of this pathway should be performed in a case-by-case basis.