Spatial and temporal variation of anthropogenic palladium in the environment

Abstract

Palladium, one of the platinum group elements (PGEs), nowadays has received increasing attention in the production of automotive catalytic converters (ACCs) (Zereini and Alt, 2000). This is due to the exceptional catalytic properties of the metallic Pd amongst PGEs, which can be utilized to a rather efficient elimination of harmful and/or toxic components of exhaust gases (e.g., CO, NOx, and hydrocarbons) released by diesel- and petrolfuelled vehicles and some household utensils. However, the hot exhaust gases, which are conducted through the converters, cause the abrasion of the internal surface (activated with metallic PGEs) of these units, and results in the emission of PGEs into the environment. As it is known (Zereini and Alt, 2000; Ravindra et al., 2004), the levels of anthropogenically evolved PGEs have been continuously increasing in nature since the introduction of ACCs. It appears that the risk of Pd to human health had been underestimated until the 80s. The allergic potential of Pd was first reported in connection with the use of Pd-rich dental restorative alloys (Van Ketel and Niebber, 1981; Castelain and Castelain, 1987; Aughtun et al., 1990). Similar observations were made with Pd chloride in human skin (epicutane) tests, which also revealed a distinct cross sensitivity to Ni. Around 90 % of the studied individuals, reacting against Ni, demonstrated sensitivity towards Pd (Olivarius and Menn, 1992). Occupational asthma caused by Pd metal has also been reported in one case (Daenen et al., 1999). In a recent study, Helm (2002) reported a likely association between elevated urinary Pd levels and diseases of the thyroid and the immune system. Therefore, it appears to be an important task to monitor the concentration of Pd in various environmental compartments and biological matrices to assess the risk of this element to human health.