Trophic-level testing

Norway Limited use of toxicity testing is made and can be applied as a statutory enforceable requirement. Trophic-level testing is conducted. 

New Zealand Effluent toxicity testing is conducted widely and can be applied as part of a permit condition. The system is flexible and leaves decisions at the regional level. Trophic-level testing generates acute and chronic data. 

The same assessment factors are used for the terrestrial compartment as for the freshwater compartment depending on the type of studies available (short term or long term), the number of trophic levels tested. It is recognized that the extent of the data package on the terrestrial environment will be small and typically limited to soil microorganisms, earthworms and higher plants. 

Dibutyltin. A larger data set exists for dibutyltin, including both acute and long-term test results. The lowest concentration identified was a chronic NOEC of 0.015 mg/1 for Daphnia magna exposure to dibutyltin chloride. Long-term values were available across three trophic levels, and, therefore, an uncertainty factor of 10 was considered appropriate. 

Bones of 19 individuals were analyzed for strontium, rubidium and zinc. The number of samples was limited by the availability of bone after the stable isotope analyses were completed. Strontium was analyzed in order to test for trophic level, and to compare to other results obtained in the region on prehistoric peoples (Katzenberg 1984). Rubidium is not expected in human bone, so its presence acts as a measure of contamination. The use of zinc as a paleodi-etary indicator has been questioned recently (Ezzo 1994) and we were interested to see if there was any relationship between zinc content in food and bone. 

Of the 188 studies reported in Tables 1, 2 and 3, more than half (n = 101) were conducted with two or more tests representing at least two biotic levels (i.e., test battery approach or TBA), as opposed to those performed with a single biotic level (n = 87). While test and biotic level selection may be based on a variety of reasons and study objectives (e.g., practicality, cost, personnel availability), preference for TBAs can also be influenced by the need to assess hazard at different levels so as not to underestimate toxicity. Indeed, contaminants can demonstrate trophic-level specificity (e.g., phytototoxic effects of herbicides) or they can exert adverse effects at multiple levels (e.g., particular sensitivity of cladocerans toward heavy metals in contrast to bacteria). When TBAs are used, they are mostly conducted with two, three or four trophic levels (Tab. 4). 

Other standardized/validated test methods reported in the literature include acute/chronic tests performed with algae (e.g, OECD, 2002a ISO, 2003), fish cells (Gagne and Blaise, 2001), invertebrates (Borgmann and Munawar, 1989 Trottier et al., 1997 Pereira et ah, 2000 OECD, 2001 a,b), Lemnaceae (OECD, 2002b), and with toxicity tests conducted at different trophic levels (Nebeker et ah, 1984 U.S. EPA, 2002a,b). 

Trophic level Toxicity test Assessment endpoint Reference... 

For both the Saint-Lawrence River Action Plan (Costan et al., 1993) and the Toyama Bay Japanese (Kusui and Blaise, 1999) studies, the two suites of bioassays employed represented three trophic levels (decomposers, primary producers and primary or secondary consumers), and sought to measure both acute and chronic toxicity. Toxicity tests were selected on the basis of practical and scientific criteria including low sample volume requirement, sensitivity, simplicity of undertaking the assay, ease in maintaining laboratory cultures, cost-effectiveness, procedural reliability and/or frequency of use internationally. 

Inclusion of a test representative of the fish level of organization in future PEEP bioassay batteries is nevertheless highly advisable owing to the specific adverse effects that liquid wastes can manifest on this trophic level. To offset the constraints mentioned above, appropriate surrogates can now be found with tests conducted with fish cells. Indeed, fish cell bioassays such as those reported in this book (see Chapters 14 and 15, volume 1 of this book) offer reliable and relevant alternatives to whole organism testing that alleviate sample volume and budgetary considerations. 

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