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The effects of various salts of platinum of palladium were determined on the parameters of the microsomal mixed-function oxidase system from rat liver. The intraperitoneal injection of PtCl4 or Pd(NO3)2 increased the hexobarbital-induced sleeping time in vivo and generally decreased the aminopyrine demethylase and the content of cytochrome P-450 in isolated hepatic microsomes. The dietary administration of various salts of platinum or palladium for 1 wk generally decreased or had no effect on the parameters of drug metabolism by isolated microsomes and after 4 or more wk generally had no effect on, or increased, the parameters. The addition of 0.15-0.2 mM PtCl4 or 0.2-0.3 mM Pd(NO3)2 to the incubation medium (containing 5 mM MgCl2) inhibited the aminopyrine demethylase of isolated hepatic microsomes by 50%.

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. The National Institute of Environmental Health Sciences (NIEHS) andBrogan & Partners are collaborating with JSTOR to digitize, preserve and extend access to Environmental Health Perspectives.The public health benefits expected by reducing known hazardous emissions from mobile sources should not be compromised by increasing levels of other potentially hazardous unregulated emissions. Catalytic converters are going to be used to meet the statutory requirements on carbon monoxide and hydrocarbon emissions from light duty motor vehicles. Platinum and palladium metals are the catalytic materials to be used in these emission control devices. Preliminary experimental evidence and analysis of the impact of these control devices on the future use and demand for platinum indicates that this metal may appear at detectable levels in the environment by the end of this decade. At the present time, platinum and palladium are not present in the public environment and represent potentially new environmental contaminants as a consequence of use of this new abatement control technology. There is relatively little information available to adequately assess the potential health hazards that may be associated with exposure to these metals and their compounds. Analysis of the environmental problems and concerns associated with possible new environmental contaminants are discussed. Limited estimates are made on community exposure by use of a meteorological dispersion model. Biodegradation potential and attention is also given to the limited toxicological information available.

Preliminary studies have been conducted on various parameters in order to assess the possible and relative toxicities of a number of metallic salts. Upon oral administration in lethal-dose experiments, two soluble Pt4+ salts were more toxic than the other salts tested. Following intraperitoneal injection in lethal-dose experiments, PbC1, was less toxic than several of the soluble or partially soluble salts of Pt'+, Pd2+, and Mn'+. An intake of a total of approximately 250 mg of Pt4+ per rat in the drinking fluid over a 30-day interva&l did not affect the activities of aniline hydroxylase and aminopyrine demethylase in rat liver microsomes. In rats receiving soluble Pt4+ salts in the drinking fluid, the highest concentration of Pt was found in the kidney and an appreciable concentration was found in the liver.

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