Critical issues in sediment bioassays and toxicity testing

During the past few years there has been a tremendous increase in sediment bioassay and toxicity testing and research. The increased activity has paralleled the development of regulatory interest and realization of the role of contaminated sediments in ecosystem degradation. Many critical issues which affect test responses, data interpretation, and extrapolation to in situ conditions, have not been adequately addressed or recognized by the scientific community. Some of these issues may significantly affect contaminant fate and effects and thereby affect the accuracy of data interpretations. Examples of these interferences are disruptive sample collection, extended sample storage, designs which alter exposure routes, improper spiking conditions and sediment dilution, and inadequate validation of laboratory responses against in situ conditions. Over-simplification of complex sediment interactions may lead to erroneous conclusions concerning the significance of moderate to low levels of contamination.