Toxic chemicals, problems with monitoring

The types of chemical contaminants that are present in water are numerous. The chemical species emerging as contaminants is ever increasing. It is estimated that 1000 new chemicals are identified in water each year. Setting standards for and monitoring such a wide array of chemicals are impractical. Acute health problems are seldom associated with toxic chemical contaminants in water except on rare cases of massive accidents where a chemical may be introduced into the water supply in very large amounts. This type of contamination is also rarely dangerous, because often the toxic chemical makes the water unsuitable for consumption due to unacceptable taste, odor, or color. Microbial contaminants, on the other hand, have acute and widespread effects, and thus require a higher priority. 

Stable activable tracers are powerful tools for the study of many environmental problems. Compared with fluorescent dyes or radiotracers, they offer many advantages that are reviewed herein. Our research group has emphasized the use of rare earth nuclides with short-lived activation products as stable activable tracers. Use of rare earth nuclides is cost-competitive with conventional tracers and allows rare earth "fingerprints to mark individual sources with subsequent simultaneous tracing of effluents from several sources. We present results from the application of these tracers to monitor pollutant dispersal from multiple industrial stacks, monitor fluid-bound pollutant dispersal in estuarine and fresh-water systems, monitor herbicide dispersal, and trace toxic organic chemicals in the marine environment. 

Sensitization may last for many years or for life it usually lessens with time and most, but not all, people slowly become desensitized. A sensitized person must avoid further work with isocyanates and also asthmatic individuals should not work with isocyanates. Many employers who use isocyanates require their employees to be medically certified as free from respiratory problems and will systematically monitor their employees for maintenance of lung function through forced respiratory volume (FRV) monitoring. Further information is provided in the BRMA code of practice entitled Toxicity and Safe Handling of Diisocyanates and Ancilliary Chemicals a code of practice for polyurethane flexible foam manufacture. 

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