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The risk associated with the inhalation of platinum group element (PGE) emissions from vehicle exhaust catalysts (VECs) has been investigated by extracting road dust and milled auto catalyst with simulated lung fluids. Gamble's solution (representative of the interstitial fluid of the deep lung) and artificial lysosomal fluid (ALF) (representative of the more acidic environment within the lung) were employed as extraction fluids. The highest PGE release was observed in ALF, implying that inhaled particles would have to be phagocytized before significant amounts of PGEs dissolve. The greatest percentage (up to 88%) of PGEs was released from road dust, possibly due to the presence of mobile PGE species formed in the roadside environment. Pt showed the highest absolute bioavailability, due to its greater concentration in the environmental samples. Pd and Rh had higher percentage of release, however, because of their more soluble nature. From the toxicological perspective, the results demonstrate potential health risks due to the likely formation of PGE-chloride complexes in the respiratory tract, such species having well-known toxic and allergenic effects on human beings and living organisms.

Platinum group element (PGE) levels in the environment have increased following the introduction of vehicle exhaust catalysts (VECs). In order to evaluate the potential pathways of PGEs from VECs into humans, a physiologically based extraction test (PBET) was used to study the uptake of PGEs by the human digestive tract. The PBET assay was implemented in two phases, to first simulate the passage of ingested soil through the acid conditions of the stomach before it enters the near neutral conditions of the small intestine. The results showed that Pt, Pd and Rh did not undergo precipitation reaction when passing from the acid environment of the stomach to the neutral environment of the small intestine. The greatest fractions of bioavailable PGEs (up to 68%) were observed in road dust samples, possibly due to the presence of mobile PGE species formed in the roadside environment. Higher percentages of Pd and Rh were bioavailable than Pt, probably due to the differences in their mobilities and tendencies to form soluble complexes. Pt showed the highest absolute bioavailability however, due to its greater concentration in environmental samples. The solubilization of PGEs in the human digestive tract could involve the formation of PGE-chloride complexes, with perhaps increased health-hazard issues because of the known toxic and allergenic effects of these species.