Toxicity testing with algae

Borthwick, P.W. and G.E. Walsh. 1981. Initial Toxicological Assessment of Ambush, Bolero, Bux, Dursban, Fentrifanil, Larvin, and Pydrin Static Acute Toxicity Tests with Selected Estuarine Algae, Invertebrates, and Fish. U.S. Environ. Protection Agen. Rep. 600/4-81-076. 20 pp. 

The major difference with the other certification systems lies in the need for toxicological safety data on the material itself (not to be confused with ecotoxicity tests after a preceding composting cycle). In the GreenPla system, the proof of toxicological safety is given by either oral acute toxicity tests with rats or environmental safety tests with algae, Daphnia or fish. Alternatively, the approval as a food additive is also sufficient. 

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). 

Requiring low-sample volume micro-scale tests for its cost-effective application, the PEEP index has thus far employed bioassays with bacteria, algae and microinvertebrates. While well-standardized toxicity tests using freshwater fish existed at the time of the PEEP s conception in the early 1990 s (e.g., the Environment Canada fingerling rainbow trout 96-h lethality test to assess industrial wastewaters), they were excluded because of their large sample volume needs (e.g., close to 400 L of effluent sample required to undertake a multiple dilution 96-h LC50 bioassay in the case of the trout test). In addition to effluent sample volume, the cost of carrying out salmonid fish acute lethality bioassays for the 50 priority industrial effluents identified under SLAP I (the first 1988-93 Saint-Lawrence River Action Plan) was prohibitive. 

Quantal toxicity tests employing organisms such as daphnids or fish do not alter the concentration of contaminant(s) in a given volume of water because they are directly introduced into their respective experimental containers. In contrast, bioassays undertaken with algae and bacteria somewhat dilute the test material since they must be introduced into test containers (i.e., flasks, tubes or microplate wells) via a certain volume of inoculum. In such tests, the volume share of the test culture can sometimes reach 20 % in the test preparation, which corresponds to a dilution of 1 1.25 (Tab. 2). This dilution stage is therefore the highest concentration that can be examined with such microbial tests. 

Standard acute toxicity tests of Ugilec 141 with bacteria and algae showed no measurable effects. In contrast, Daphnia toxicity was comparable to that of a PCB formulation Clophen A60. The EC100, EC50, and ECO values were 520 pgl-1, 180 pgl-1, and 60 pgl 1 for Ugilec 141, and 420 pg l-1,190 pgl, and 53 pg l-1 for Clophen A60, respectively [100]. 

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