radation occurs via random scission: Hydrolysis must proceed slowly enough to minimize effects of nonhomogeneity, the initial molecular weight must be great enough, and consideration must be given to formation of water-soluble substances as a result of the degradation. {Macromolecules 1996, 29, 3303-07)
GROUNDWATER Fungicide leaching Metalaxyl is a soluble fungicide used on golf greens, tees, and other turf grass. Knowledge of its downward migration is needed to understand risks to groundwater supplies. D. J. Lisk and colleagues studied its leaching behavior in lysimeters that simulated golf greens. Metalaxyl was applied at a rate of 1.2 lb/acre. The turf was exposed to natural rainfall and 2-3 cm/day of irrigation. Growing turf grass in a mixture of peat and sand delayed leaching of metalaxyl but increased total metalaxyl in the leachate As turf density increased from 0% (only sand present) to 100% total leachate volume increased but total metalaxyl recovered in the leachate decreased from 36 to 16% {Chemosphere 1996 33 2335-40)
HEALTH Air pollution endpoints Quantitative knowledge about the chronic health effects of air pollutants is scanty yet critical to analysis of the cost-effectiveness of abatement measures. K. Aunan used a literature review of epidemiological reports to recommend exposureresponse functions that relate ambient air pollution concentrations to the frequency of various health effects. The study examined acute and chronic respiratory symptoms in adults and children, crude mortality, ciiicl inn £ C3,ncer incidence. In most health effects were attributed to a single which was total suspended particulates The author proposes a calculation to estimate annual symptom days for short-term health effects based on average annual concentration of pollutants {Risk Anal 1996 16 693-709)
Extraction method reduces solvent use Laboratories are trying to reduce use of chlorinated solvents to protect the health of lab personnel and minimize waste production. Accelerated solvent extraction (ASE) can reduce solvent use by orders of magnitude in the extraction of solid samples. J. A. Fisher and colleagues compare the new technique with Soxhlet extraction and bath sonication/shaking extraction for organochlorine pesticides (OCPs) and polycyclic aromatic hydrocarbons (PAHs). In spiked samples ASE had higher recoveries than Soxhlet extraction for most analytes including organochlorine pesticides But there also were higher levels of background interferents In actus! soil samples ASE was pouivalent or iiinprior to bath sonication/shaking f o r P A H b u t it hart ImA/Pr recoveries OCP"! (Environ 9r; TPrhnol this issue,D 1120-27)
U.S. pesticide levels Public health authorities have emphasized the need for baseline data on pesticide levels in humans. R. H. Hill and colleagues presented measurements of 12 pesticide biomarkers in urine samples from a representative sample of 1000 U.S. residents. The data provide reference values for risk assessment, trends analysis, and comparisons in studies of potentially highly exposed populations. Six of the analytes were detected in more than 50% of the population. One, 2,5-dichlorophenol, was detected in 98% of samples suggesting that almost all of the population was exposed to its parcompound 1 4-dichlorobenzene commonly used in moth crystals and toilet deodorizers Based on previous data human exposure to chlornvrifos aDnears to be increasing whereas DentachloroDhenol exposure seems to be decreasine [Environ Res .995 ,7 99-108)
MEASUREMENTS SPME for air Solid-phase microextraction (SPME) is an alternative to existing methods for extracting many organic analytes from aqueous systems and corresponding headspaces. P A. Martos
and J. Pawliszyn report that SPME has similar potential in sampling airborne compounds. In their procedure, air is sampled with a 100-um fiber poly(dimethylsiloxane) fiber. The SPME sampler reaches equilibrium with the air within 450 s. Because partition coefficient (K) varies with temperature, K must be determined at the sampling temperature for each compound. The SPME is then analyzed by gas chromatography with flame ionization detection. Results are shown for a series of hvdrocarbons with sensitivity greater than conventional grab samDling and an RSD of less than 9% {Anal Chem 1997 69 206-15)
Breath sample analysis Industrial hygienists use exhaled breath sampling to monitor workers' exposure to several volatile organic compounds. Current methods are not suitable for large-scale field monitoring because they require laboratory analysis of collected samples and are not sufficiently specific. W. A. Groves and E. T. Zellers describe a prototype portable instrument that can selectively measure organic vapors in breath at low- and sub-ppm concentrations. The instrument uses Ft Tl Ft YYFt V
of surface tic wttve sensors as w e l l a.s COIT1DOnents for sample preconcentration and thermal desorption Concentration measurements with the instrument compared favorably with measurements by gas chromatographv The selective monitoring properties of this multisensor array also make such dpvirps suitable for continuous air mnnitnrine annlirations (Am ,
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Contributors: Michael Brauer, University of British Columbia, Vancouver, Canada; Brian Eitzer, Connecticut Agricultural Experiment Station, New Haven, Conn.; Stephen Geiger, Remediation Technologies, Inc., King of Prussia, Pa.; Vincent Hand, Miami University, Institute eo Environmental Sciences, Oxford, Ohio; Louis Kovach, Ecolife Associates, Wilmington, Del; Geoffrey Nobes, McGiil University, Montreal; Raewyn Town, Queen'' University of Belfast, Northern Ireland; ;nd Margaret Whittaker, NSF International, Ann Arbor, Mich.
VOL.31, NO. 4, 1997 /ENVIRONMENTAL SCIENCE S TECHNOLOGY / NEWS " 1 6 9 A
