Effects of platinum and palladium salts on parameters of drug metabolism in rat liver.

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%.

Effect of platinum and palladium salts on thymidine incorporation into DNA of rat tissues.

The intraperitoneal administration of PtCl4 or Pd(NO3)2 at levels of 28 or 56 mumole/kg body weight decreased the thymidine incorporation into DNA of spleen, liver, kidney, and testis. Spleen was most sensitive to both the platinum and the palladium salt. In liver, DNA syntheses in parenchymal cells and stromal cells were about equally sensitive to PtCl4. In control rats, only 20-30% of the 3H in the acid-soluble fraction of liver or spleen was in the form of thymidine and its phosphate esters 2 hr after the intraperitoneal injection of 3H-thymidine; prior injection of PtCl4 (56 mumol/kg body weight) did not change the pattern.

Exposure to halogenated hydrocarbons in the indoor environment.

The indoor environment has frequently been ignored as a significant source of exposure to air pollutants. To date there are a number of documented examples of levels of indoor air pollutants greatly exceeding those levels which commonly occur in the outdoor environment. Among these instances are airborne buildup of polynuclear aromatics and cadmium from cigarette smoke, lead from burning candles, and vinyl chloride from use of aerosols containing this substance as a propellant. These examples suggest that there may be additional sources of indoor air pollutants, particularly halogenated hydrocarbons from aerosol products, which have heretofore not been generally recognized as important. The present paper endeavors to review those instances where halogenated hydrocarbons in the indoor air environment may build up to concentrations of potential public health concern. These considerations may be especially relevant in future years as increasing efforts are being made to insulate buildings more efficiently as a means to conserve energy. The available data strongly suggest that halogenated hydrocarbons are an important class of air pollutants in the indoor environment and that their presence in the outdoor environment should also be carefully examined. In this regard, halogenated hydrocarbons in the outdoor environment may also contaminate indoor air spaces.

Noble metals: a toxicological appraisal of potential new environmental contaminants.

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.

Studies on the evaluation of the toxicity of various salts of lead, manganese, platinum, and palladium.

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 intraperiotneal injection in lethal-dose experiments, PbCl2 was less toxic than several of the soluble or partially soluble salts of Pt4+, Pd2+, and Mn2+. An intake of a total of approximately 250 mg of Pt4+ per rat in the drinking fluid over a 30-day interval 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 appreciiable concentration was found in the liver.