Defining an exposure-response relationship for suspended kaolin clay particulates and aquatic organisms: work toward defining a water quality guideline for suspended solids.

Water quality guidelines for suspended solids generally rely on the percentage departure from reference condition, an approach that has been criticized. Attempts to develop a biological effects-base guideline have, however, been confounded by low data availability. Furthermore, the high biological response variability to suspended solids exposure suggests that organisms are responding not only to exposure concentration and duration but also to other mechanisms of effect associated with suspended particles (e.

Review of toxicological effects caused by episodic stressor exposure.

Water quality monitoring tools that rely on data from stress-response tests with continuous exposure at constant concentrations are not always appropriately protective when stressor exposure in the field is episodic in nature. The present study identifies various approaches that have attempted to account for episodic stressor exposure, describes the development of a toxicological effects database of episodic stressor exposure collated from published scientific literature, and discusses whether any discernible trends are evident when these data are reviewed. The episodic stressor exposure literature indicated that few generalizations can be made regarding associated biological responses.