Study offers guidance for optimizing TIE study design

SCCWRP and its partners have completed a two-year study examining how to optimize the design of toxicity identification evaluation (TIE) studies to improve confidence in the results.

The project, published as a SCCWRP technical report in January, involved oversampling in Consolidated Slip, an area of the Los Angeles Harbor with high sediment toxicity levels, and then using statistical analysis to develop best-practices recommendations for TIE study design.

Among the study’s recommendations is to conduct TIEs at a minimum of three locations within a study site. Researchers also should compare observed contaminant concentrations to known toxicity thresholds to help reduce uncertainty in interpreting results.

TIEs are the primary method used by water-quality managers to determine the cause of toxicity in a water or sediment sample. The analysis typically includes a series of chemical treatments of the sample to selectively remove or alter the toxicity of specific contaminant groups, such as trace metals, nonpolar organics and pyrethroid pesticides.