Harmonization of Water and Sediment Quality Guideline Derivation

With increasing numbers of new chemicals reaching the marketplace, there is an ongoing need for defensible estimates of the concentrations of chemicals that should provide an acceptable level of protection to aquatic ecosystems, including both the water column and sediments. Depending on the jurisdiction, these “safe” concentrations are called Guidelines or Guideline Values (Australia and New Zealand, and Canada), Water Quality Criteria (USA), or Environmental Quality Standards (EQSs) (European Union). The standards and criteria are typically legal limits whereas the guidelines have no legal status and are used to indicate when concentrations of chemicals may be exerting a non-acceptable impact and further action is required to assess the actual magnitude of the impact. Throughout this article, the term guideline value (GV) is used to describe the various “safe concentrations”. For each chemical, the derivation of water quality GV requires extensive toxicity testing on a large number of species from different taxonomic groups. The considerable costs that this involves, makes it highly desirable that acquiring such data is shared across multiple jurisdictions, such that GVs derived in Canada, for example, are equally applicable to Australia and New Zealand, the United States or the European Union (EU). The development of water quality GVs has largely occurred independently in jurisdictions, although in many instances they are based on common or very similar sets of published ecotoxicity data.