bicity. [Environ. Toxicol. Chem. 1995, 14(10), 1675-85]
MONITORING Cysts and oocysts Accurate, selective detection of Giardia cysts and Cryptosporidium oocysts in water supplies is essential for the proper monitoring and operation of drinking water treatment systems. M. R. Rodgers and colleagues have advanced a method to eliminate the interference from species of algae on current detection methods. They modified the American Society for Testing and Materials immunofluorescence method for detection of these organisms and tested for cross reaction with 54 algal species. Twenty-four exhibited some cross reaction. The investigators found that adding goat serum to the test matrix eliminated most of the algal cross reactivity and reduced background fluorescence. The method can be applied for more selective and accurate detection of these organisms in raw and drinking water samples. [Appl. Environ. Microbiol. 1995, 61(10), 3759-63]
POLICY Uniform risks assessment Environmental risks cannot be uniformly assessed and prioritized under current EPA programs and policies because of limited agency authority and lack of uniformity among environmental statutes. F. H. Habicht II addressed reforms that could enable EPA to uniformly assess risk while accommodating economic, social, and political factors. Reforms include legislating greater EPA discretion over its programs and budget allocations, increasing the use of comparative risk assessment, and refining risk assessment default values and methodologies. [Risk Policy Report 1995, 2(9), 21-22]
SOIL Bromide tracer uptake Because of bromide's low natural concentrations and low reactivity in the soil, it is often used as a hydrologic tracer or is mixed with nitrate
Seeking zero-valent iron's reaction mechanism Zero-valent iron has been shown to chemically reduce chlorinated hydrocarbons quickly and cheaply in laboratory and field demonstrations, but the mechanism this process uses is still uncertain. L I. Hardy and R. W. Gillham attempted to determine the reaction mechanism and products of iron in aqueous solutions. Hydrocarbons ranging from methane to pentanes were produced from aqueous C02 and subjected to the metal. The product distribution was similar to that found with Fischer-Tropsch hydrocarbon formation from CO and H2 over a metal catalyst. Results suggest that the reduction rate of chlorinated organics in groundwater cleanup may be limited by adsorption of hydrocarbon products onto the iron. (Environ. Sci. Technol., this issue, 57-65)
to measure denitrification rates. However, bromide uptake by growing crops may influence its use for these functions. R. R. Schnabel and colleagues added a bromide tracer to soils in which rye grass was grown. A wide range between 8 and 86% of the bromide was taken up by the crop. Results indicated that use of bromide in soil systems in which plants are actively growing can result in an error in determining transport properties or denitrification. (J. Environ. Qual. 1995, 24, 888-92)
TOXICOLOGY Predicting chronic toxicity An accurate method to predict chronic toxicity from acute toxicity data would reduce costs and increase the number of chronic estimates available. K. Sun and co-workers applied accelerated life testing to make such predictions. Accelerated life testing has been used to predict the service life of manufactured products. The researchers recorded the time of death for individuals exposed to various concentrations of toxicant. These data are fit to a model, which extrapolates from high to low dose and from short to long exposure times. Predictions compare favorably with measured chronic toxicity in most of the 26 cases stud-
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ied. [Environ. Toxicol. Chem. 1995, 14(10), 1745-52]
WASTEWATER Total chlorine-free effluent Concerned about chlorinated organic compounds, managers of kraft pulp mills are using elemental chlorine-free (ECF) and totally chlorinefree (TCF) bleaching processes. But there have been few studies of TCF wastewater. R. Saunamaki analyzed wastewater from a mill that converted to ECF with chlorine dioxide bleaching and TCF with peroxide bleaching. Chlorine compounds and COD in the mill effluent were reduced, and color was lightened, especially in TCF bleaching. However, effluent toxicity increased from excess peroxide in the TCF effluent, nitrogen emissions increased, and heavy metals removal efficiency decreased. [TappiJ. 1995, 78(8), 18592]
Pretreating wastes Hazardous waste can have toxic effects on activated sludge organisms, volatilize into the atmosphere, limit land disposal of sludges, and pass through water treatment systems without being removed. M. J. Kupferle and colleagues investigated anaerobic pretreatment of industrial wastes as a means to eliminate these problems. They studied bench-scale, fluidized, expanded-bed, granular activated carbon (GAC) systems with anaerobic biomass. The GAC beds were fed primary effluent spiked with 5% landfill leachate and 14 hazardous waste compounds. Compounds were adsorbed by the GAC, which was subsequently taken off line to allow biodegradation to occur. Results indicated effective removal of organics and regeneration of GAC. [Water Environ. Res. 1995, 67(6), 910-20] Contributors to Research Watch are Brian Eitzer, Connecticut Agricultural Experiment Station, New Haven, CT; Stephen Geiger, Remediation Technologies, Inc., King of Prussia, PA; Vincent Hand, Miami University, Institute of Environmental Sciences, Oxford, OH; Richard Hurst, CHEMPET Research Corp., Moorpark, CA; Louis Kovach, Ecolife Associates, Wilmington, DE; and Margaret Whittaker, NSF International, Ann Arbor, MI.
