Platinum group elements in the environment: emissions and exposure

PGEs (Pt, Pd, Ru, Ir, and Os) are a relatively new group of anthropogenic pollutants. Specific useful properties of these metals (high resistance to chemical corrosion over a wide range of temperatures, high melting point, high mechanical resistance, and high plasticity) have fomented rapid growth of new and existing applications in various economic and industrial sectors. These metals are not only used in the chemical, petrochemical, electrical, and electronics industries but also PGE use, in various industries, has dramatically increased emissions of these metals to the environment; emissions from vehicle catalytic converters and hospital wastewater discharges are particularly significant. The environmental benefits of using PGEs in vehicle catalytic converters are clear. These metals catalyze the conversion of toxic constituents of exhaust fumes (CO, HCs, NOxs) to water, CO2, and molecular nitrogen. As a result of adverse physico-chemical and mechanical influences on the catalyst surface, PGEs are released from this layer and are emitted into the environment in exhaust fumes. Research results indicate that the levels of such emissions are rather low (ng km(-1)). However, recent data show that certain chemical forms of PGEs emitted from vehicles are, or may be, bioavailable. Hence, the potential for PGEs to bioaccumulate in different environmental compartments should be studied, and, if necessary, addressed. The use of Pt in anticancerous drug preparations also contributes to environmental burdens. Pt, when administered as a drug, is excreted in a patient's urine and, as a consequence, has been observed in hospital and communal wastewater discharges. Few studies have been published that address bioavailability, mode of penetration into live organisms, or environmental fate of PGEs. The toxic effect of these metals on living organisms, including humans, is still in dispute and incompletely elucidated. Contrary to some chlorine complexes of Pt, which most frequently cause allergic reactions, the metallic forms of PGEs are probably inert; however, they may undergo transformation to biologically available forms after release to the environment. Because exposure to PGEs may result in health hazards, it is necessary to evaluate the risks of human exposure to these metals. Available data show that the highest exposed groups (Leceniewska et al. 2001) are individuals who work in refineries, chemical plants, electronics plants, jewelry production, oncological wards (medical personnel), and road maintenance; also highly exposed are women who have silicone breast implants. The effects of PGE exposure in live organisms include the following: asthma, miscarriage, nausea, hair loss, skin diseases, and, in humans, other serious health problems. As production and use of PGEs grow, there is a commensurate need to generate additional experimental and modeling data on them; such data would be designed to provide a better understanding of the environmental disposition and influence on human health of the PGEs.