In Vitro Inhalation Bioaccessibility of Phthalate Esters and Alternative Plasticizers Present in Indoor Dust Using Artificial Lung Fluids

Phthalate esters (PEs) are used as plasticizers in consumer products. Their low migration stability has resulted in the classification of PEs as major indoor contaminants. Because of PE's ubiquity and adverse health effects on humans and especially children, non-phthalate alternative plasticizers have been introduced into the market. This is the first study of in vitro inhalation bioaccessibility of PEs (e.g., DMP, DEP, and DEHP) and alternative plasticizers (e.g., DEHT and DINCH) via indoor dust to assess inhalation as an alternative route of exposure. Two artificial lung fluids were used, mimicking two distinctively different pulmonary environments: (1) artificial lysosomal fluid (ALF, pH 4.5) representing the intracellular acidic lung fluid inhaled particle contact after phagocytosis by alveolar macrophages and (2) Gamble's solution (pH 7.4), the extracellular healthy fluid for deep lung deposition of dust. DMP and DEP were highly bioaccessible (>75%), whereas highly hydrophobic compounds such as DEHP, DINCH, and DEHT were <5% bioaccessible via both artificial lung fluids. Our findings show that the inhalation bioaccessibility of PEs is primarily governed by their hydrophobicity and water solubility. Further research is necessary to develop unified and biologically relevant inhalation bioaccessibility tests, employed as part of human risk assessment of volatile and semivolatile organic pollutants.