Criteria-based procedure for selecting test methods for effluent testing and its application to Toxkit microbiotests

Abstract

In recent years there has been increasing development of methods (particularly rapid tests) for testing environmental samples. If appropriate methods are to be used for a particular operational role then it is necessary to adopt a robust and objective selection mechanism. This paper describes the application of a criteria-based procedure to the selection of test batteries of methods for use in effluent testing. In the procedure tests are scored against a series of criteria with the exact criteria used depending on the operational role and form of test (for example rapid or conventional). Examples of criteria used include: previous application of a method to an operational role, discrimination between samples, influence of physico-chemical parameters, ease of use, test duration, test costs, test capability (sensitivity and spectrum of response) test precision (repeatability and reproducibility), availability of a standard operating procedure, availability of test organisms, test organism variability, the use of indigenous test organisms, importance of test organisms, the relationship between the data for rapid and conventional tests and the ecological relevance of test endpoints. To ensure each method is assessed in a consistent way test scores are assigned using defined guidelines and for certain criteria methods have to satisfy a threshold requirement otherwise they are not deemed to be suitable for the intended purpose. The use of the procedure has been demonstrated by considering the suitability of a series of Toxkits and, where appropriate, their conventional counterparts for effluent assessment.