A draft of Environment Canada's “Guidance on Control of Test Precision Using a Spiked Control Sediment Toxicity Test” was reviewed by an international technical subcommittee. Comments were received, assessed, and discussed by members of the project steering committee, at which time, it was decided that in order to accommodate the recommendations of the subcommittee members, the revision of the document would be delayed until the results of some major sediment spiking and sediment formulation research initiatives were available.

A minimum of ten critical issues were identified by the reviewers and these issues have been summarized and briefly discussed in light of the consensus reached by the subcommittee. The data published in recent months in the scientific literature have helped to resolve some of the issues, or at least provide supporting evidence for some of the decisions that have been reached. However, one of the most contentious and critical issues that has not been resolved is the type and nature of the test medium to be spiked. In order to expand the scope beyond assessment of test precision to include interlaboratory comparisons and performance evaluation, it was decided that a formulated or artificial sediment option would be recommended as an alternative to field-collected sediments. This approach appears germane to several regulatory programs and there are currently a number of on-going research initiatives that are in the process of developing and testing the use of formulated sediments. Results of some recent experiments designed to study the effects of different formulations of sediment on survival and growth of the amphipod, Hyalella azteca, the chironomid, Chironomus riparius, and the mayfly, Hexagenia spp., as well as reproduction in the oligochaete worm, Tubifex tubifex, are presented and the implications for guidance development discussed.