Mexel 432 Toxicity to Cladoceran And Fathead Minnow During Continuous or Daily Intermittent Exposures

In many countries, numerous process and chemical products or fo1IDulatjons are used to control fouling organisms development in industrial water cooling circuits_ But, most of these processes are in opposition with environment safety. In the aim of reconcile the two positions, Mexel 432, a new anti-fouling product with anti-rust and certainly anti-scale activities, is developed (Mexel SA, 59 Haubourdin, France), In opposition with other anti-fouling agent, Mexel is used in daily intermittent exposure of 5 to 80 minutes per day. This process could allow to use a small product dose. In previous studies,·Mexel toxicity to cladoceran, as median effective concentration (EC₅₀), was between 6.5 and 3100 µg/L (Brooke, 1996; IR.CHA, 1990). In this report. we studied (1)·the toxicity of two M el batches to cladoceran (Daphnia magna) during 48-h continuous exposure in ISO water (Guideline ISO 6341) and in Lake Superior water (Wisconsin, USA), (ii) for one of the two batches, Mexel toxicity to fathead minnow (Pimephales promelas) during 96--h continuous exposure in Lake Superior water and {iii)for the same batch, Mexel toxicity to cladoceran and fathead minnow during 96-,h tests with one daily intermittent exposure of 5> 20 and 80 minutes