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Phthalate esters (PEs) are plasticiser additives imparting durability, elasticity and flexibility to consumer products. The low migration stability of PEs along with their ubiquitous character and adverse health effects to humans and especially children has resulted in their classification as major indoor contaminants. This study assesses inhalation exposure to PEs via indoor dust using an in vitro inhalation bioaccessibility test (i.e. uptake) for of dimethyl phthalate (DMP), diethyl phthalate (DEP) and di-(2-ethylhexyl) phthalate (DEHP) and the alternative non phthalate plasticisers bis(2-ethylhexyl) terephthalate (DEHT) and cyclohexane-1,2-dicarboxylic acid diisononyl ester (DINCH), exposure. Using artificial lung fluids, which mimicktwo distinctively different pulmonary environments, namely artificial lysosomal fluid (ALF, pH = 4.5) representing the fluid that inhaled particles would contact after phagocytosis by alveolar and interstitial macrophages within the lung and Gamble's solution (pH = 7.4), the fluid for deep dust deposition within the pulmonary environment. Low molecular weight (MW) PEs such as DMP and DEP were highly bioaccessible (> 75 %) in both artificial pulmonary media, whereas highly hydrophobic compounds such as DEHP, DINCH and DEHT were < 5 % bioaccessible via the lung. Our findings show that the in vitro pulmonary uptake of PEs is primarily governed by their hydrophobicity and water solubility, highlighting thus the need for the establishment of a unified and biologically relevant inhalation bioaccessibility test format, employed within the risk assessment framework for volatile and semi-volatile organic pollutants.

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