Research Watch: Contaminated rooms - Environmental Science

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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

VOL. 3 1 , NO. 11, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 4 9 3 A