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Direct Toxicity Assessment
SEE ALSO - Chemical Testing

Direct Toxicity Assessment

Direct Toxicity Assessment (DTA) is the branch of ecotoxicology that is concerned with the measurement and interpretation of the toxicity of contaminated water, sediment or soil samples using species and responses that are considered to be relevant to that medium. DTA is gaining increasing acceptance as a tool in regulating and monitoring the quality of effluents and receiving water in Europe and elsewhere. The Environment Agency in England and Wales and Scottish Environment Protection Agency (SEPA), in Scotland, have explored the use of DTA in various contexts, including pollution control, and the EU Water Framework Directive makes provision for using it for assessing the quality of surface waters.

DTA differs from product testing in that the effects observed in the toxicity tests conducted on water, sediment or soil samples cannot necessarily be explained in terms of concentrations of uniquely identifiable chemical substances. Instead, DTA has the capacity to determine the integrated toxic effects of all the contaminants present in a sample. DTA data can be used for assessing the overall toxic hazard posed by, for example, an aqueous discharge or for assessing the significance of ambient levels of environmental contamination.

In addition to its primary use for determining sample toxicity, DTA also has the unique feature of being able to be used for tracking toxicity through a network of watercourses or through a municipal or industrial sewer network. This feature can be extended to identifying the chemical fractions responsible for sample toxicity (e.g. metals, organics) through testing coupled with a range of sample manipulation techniques.

Peter Fisk Associates has significant experience in the use of DTA procedures for assessing effluent discharges from industrial and municipal sources and have a good understanding of the regulatory framework within which they can be applied. Contact us for more information.