susceptible to oxidative degradation, they did not undergo extensive decomposition in a simulated composting environment, possibly because of limited exposure times at selected reaction conditions. (/. Environ. Polym. Degrad. .197, 5(3), 137-51)
Enzymes for waste treatment Opportunities for enzymes to treat liquid, solid, and hazardous waste streams have been studied by various researchers. Enzymes remove pollutants by precipitation or convert them to value-added products or materials that are more amenable to further treatment by other methods. J. Karam and J. A. Nicell reviewed potential waste treatment applications. They report that the use of enzymes for waste treatment is not widespread because of uncertainty about byproduct characteristics, disposal of tion products, and high costs of enzymatic treatment processes. Moreover further optimization is needed to match specific f*n 7 v m p*i
to specific waste treatment processes (J Chem Technol Biotechnol 1997 69 141-153)
HEALTH Fuel vapor evaluation Petroleum-based fuels used in vehicles contain toxic chemicals, including known carcinogens. Brief chemical exposures during vehicle refueling affect many people and may be a major source of population exposure to several toxic compounds. L. Backer and colleagues measured gasoline constituents in blood and in the personal breathing zone of individuals before and after they pumped regular or oxygenated gasoline. Levels of benzene, ethylbenzene xylene, and toluene in blood significantly increased after pumping gasoline. Personal breathing zone samples during refueling indicated the presence of airborne gasoline in parts million and lower levels The study demonstrates that people are briefly exposed to low levels of known carcinogens and potentially toxic gasoline constituents while DumDine eas [Environ Health Pertnect 1997 ,05 SSO-SSS)
Solubility of lead in soil The effect of increased soil phosphate levels on the solubility of lead can be predicted using theoretically derived solubility equilibrium data, but experimental data needed to strengthen estimates are scarce and are not applicable to all soil conditions. S. Sauve and co-workers measured total dissolved lead and free Pb2+ concentrations for a synthetic lead phosphate mineral under typical soil conditions. Total dissolved lead was high at low pH, decreased until pH 6, then increased again as alkalinity increased. Increased levels of dissolved lead under alkaline conditions were attributed to complexation by solubilized soil organic matter These results suggest that in remediation of lead-contaminated soils the pH
