RESEARCH WATCH AIR Contaminated rooms Although microbiological contamination of buildings is recognized as a major contributor to adverse health effects associated with sick building syndrome, microbial contaminants are frequently difficult to identify. Surrogate indicators of their presence, which are more easily detected and measured, are needed to assess building health. K. Wilkins and colleagues developed a method for classifying microbially contaminated rooms based on a hypothesis that dust functions as a sink for volatile organic compounds, many of which are microbial metabolites or their derivatives. The compounds can be thermally desorbed from collected dust samples and analyzed by GC and MS. Detected distribution patterns and amounts of these compounds suggest the nature and degree of mold growth in buildings. {Indoor Air 1997, 7, 128-34)
Improving air quality Routine maintenance and cleaning can improve the indoor air quality of nonproblem buildings, but the environmental impact of these operations has not been extensively quantified. D. Franke and co-workers monitored levels of biological, chemical, and particulate pollutants in buildings to determine the influence of a one-time intense and an improved routine cleaning on indoor air quality. Compared with baseline measurements taken during routine cleaning operations, total airborne dust, volatile organic compounds, and bacteria and fungi levels were reduced after the intense and improved routine cleaning programs were implemented. The results demonstrate the importance of these cleaning programs in improving indoor air quality and preventing serious indoor pollution. {Indoor Air 1997, 7, 41-54)
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Pesticide leaching behavior Nonpolar organic compounds are not easily leached from humic substances by percolating water. Y-Y. Chien and co-workers studied the humic acid solubilization of atrazine, a widely used agricultural pesticide of environmental concern. They studied the 19F nuclear magnetic resonance relaxation of atrazine by paramagnetic probes added to a concentrated, aqueous humic acid solution. A hydrophilic anionic probe induced no relaxation, whereas a hydrophobic neutral probe caused rapid paramagnetic relaxation. These results confirm that atrazine occupies a hydrophobic domain accessible only to neutral hydrophobic molecules and suggest that the pesticide resides in the hydrophobic interior of humic acid micelles. (Environ. Sci. Techno!., this issue, pp. 3204-08)
Indoor air measurements Because of the scarcity of data reporting on concentrations and characteristics of particulates in nonproblem buildings, it is difficult to establish acceptable indoor air contaminant levels necessary for protection of human health. K. Leese and co-workers used a laser particle counter, a fine-particle sampler, and a high-volume, small-surface sampler to characterize particle size distributions, measure total airborne dust mass concentrations, and assess dust levels on floor surfaces. They found that carpets are an important particle reservoir, and as carpet dust is disturbed, dust levels decrease while airborne particulate levels increase. In addition, they found that indoor particle counts are consistently lower than outdoor measures. {Am. Ind. Hyg. Assoc. J. 1997, 58, 432-38)
BIOREMEDIATION Chlorophenol degradation Although biodegradation is the principal chlorophenol removal mechanism in soils, groundwater, and aquatic sediments, its degradability relative to the ortho, meta, or para positioning of chlorine in these compounds is not well understood. P. Jin and S. Bhattacharya studied the toxicity and chlorine site-selective biodegradability of chlorophe-
0013-936X/97/0931-493A$14.00/0 © 1997 American Chemical Society
nols in an anaerobic propionate enrichment culture. Propionate is an important intermediate in anaerobic digestion. Results indicate that trichlorophenols are more toxic than dichlorophenols or monochlorophenols and that most of the chlorophenols studied were reductively dechlorinated; dechlorination occurs most frequently at the ortho position. The authors present an overall removal scheme for the chlorophenol compounds studied. {Water Environ. Res. 1997, 69(5), 938-47)
Solvent degradation Chlorinated solvents, a major source of environmental contamination, are not easily degraded under natural environmental conditions. By using organisms that are able to cometabolize them, they can be broken down much more rapidly than would otherwise be possible. R. Ely and colleagues used an ammoniaoxidizing bacteria, Nitrosomonas europaea, to degrade 1,1-dichloroethylene, chloroform, trichloroethylene, 1,2-dichloroethane, and carbon tetrachloride in the presence of ammonia. A complex mathematical model was developed and used to analyze the cometabolism process. They found that trichloroethylene, chloroform, and 1,1-dichloroethylene inactivated the bacteria, and 1,1-dichloroethylene was the most potent deactivator. Carbon tetrachloride was not cometabolized by N. europaea, but 1,2-dichloroethane was
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Corrosion boosts wastewater metal levels Heavy-metal contamination of wastewater effluents and biosolids by corrosion of drinking water distribution systems is known to occur but has not been studied extensively. R. Isaac and co-workers analyzed concentrations of lead and copper in aqueous samples taken from the water production, distribution, and wastewater treatment systems of four cities in Massachusetts. In two of the systems studied, domestic wastewater effluent concentrations of lead and copper were significantly higher than in influent source waters. These results support other findings that drinking water systems can be major contributors of heavy metals to companion wastewater systems. The study suggests a need to evaluate and control corrosion throughout the entirety of the municipal water distribution system infrastructure. (Environ. Sci. Techno!., this issue, pp. 3198-3203)
readily oxidized and had no inhibitory effects. (Biotechnol. Bioeng. 1997, 54(6), 520-34)
GREEN CHEMISTRY Biodegradable hydrogels Although hydrogels are widely used in treating wounds, growing macromolecular crystals, and other applications, they are not easily biodegraded, and their disposal presents environmental problems. M. Tomida and colleagues studied the properties of hydrogels produced by y-irradiation of poly(aspartic acid) synthesized by thermal polycondensation. Hydrogel formation required controlled conditions and the use of high molecular weight poly(aspartic acid). The swelling and biodegradation behaviors of the synthesized hydrogels were studied. A maximum swelling of 3400 g of water per gram of dry hydrogel was observed. When placed in activated sludge, biodegradation of the hydrogel (about 50% in 28 days) was almost equal to that of free poly(aspartic acid). {Polymer 1997, 38(11), 2791-95)
GROUNDWATER
1982 and 1995. Temporal changes in detection frequency and concentration were found only for atrazine and metolachlor and were consistent with long-term use patterns. Data were judged insufficient for assessing whether groundwater quality had improved during this time as a result of agricultural chemical use practices. (J. Environ. Qual. 1997, 26, 1007-17)
HEALTH MTBE exposure analysis MTBE, a widely used fuel oxygenate, may pose a health hazard. The reliability of exposure assessments must be improved. T. Buckley and coworkers exposed two human subjects to environmentally relevant air concentrations of MTBE, made body burden measurements, and used a mathematical model to assess inhalation exposure. Equilibrium amounts of MTBE in blood were 8-11 times greater than the MTBE concentration in air at nominal exposure conditions, based on an analysis of model parameters that include MTBE residence time in blood and breath, blood-to-breath partition coefficient, and fraction of air concentration exhaled at equilibrium by the test subjects. (J. Air Waste Manage. Assoc. 1997, 47, 739-52)
Contamination trends Pesticides and other chemicals used in agricultural applications can leach through soil and contaminate groundwater. Long-term trends in this behavior must be understood to assess potential health risks. D. Kolpin and colleagues analyzed concentrations of nitrate, alachlor, atrazine, cyanazine, and metolachlor in groundwater collected from 1019 municipal wells in Iowa between
Skin sensitivity assay Reliable tests are needed to identify and assess health risks associated with chemicals that cause contact sensitization. I. Kimber and D. Basketter evaluated the murine local lymph node assay, a novel predictive test for identifying skin-sensitizing chemicals. The authors report that the assay is more objective than conventional predictive test procedures that use
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guinea pigs as subjects. A method is indicated for assessing health risks by comparing the sensitization potency of test chemicals with an index chemical for which the dose-response relationship is already well known. (Hum. Ecol. Risk Assess. 1997, 3(3), 385-95)
MEASUREMENTS Herbicide analysis Monitoring sulfonylurea herbicides in environmental waters requires reliable quantitation methods that can detect low parts-per-trillion concentrations of these compounds. A. Di Corcia and colleagues developed a novel trace analysis method that involves solid-phase extraction using a graphitized black carbon cartridge; herbicide isolation by differential elution; and fractionation and quantitation using LC and UV detection. Results indicate method detection limits for sulfonylurea herbicides of 0.6-2 ng/L in drinking water, 2-9 ng/L in groundwater, and 13-40 ng/L in river water. {Anal. Chem. 1997, 69(14), 2819-26)
PCB quantitation errors Some reported trends in PCB levels derived from long-term monitoring studies may be artifacts. J. Butcher and co-workers developed an approach to interrelate data obtained by applying several different gas chromatographic measurement methods. They used their technique to evaluate an extensive, historic database of packed- and capillarycolumn quantitations of PCB levels in fish taken from the Hudson River. Results indicate that erroneous estimates of the declining natural rate of PCB contaminant levels arise if the data are not corrected and reported consistently before being analyzed. The authors caution that failure to account for differences among quantitation methods could also invalidate PCB bioaccumulation analyses. (Environ. Toxicol. Chem. 1997, 16(8), 1618-23)
Phenols in river water Official analytical methods for detecting methylphenols, nitrophenols, and chlorophenols in water are not straightforward and can produce erroneous results. D. Puig and colleagues have developed a new, vali-
