Aquatic toxicology of cypermethrin. I. Acute toxicity to some freshwater fish and invertebrates in laboratory tests

Cypermethrin is a synthetic pyrethroid. Its acute toxicity to ten freshwater invertebrates (Daphnia magna, Asellus aquaticus, Gammarus pulex, Cloeon dipterum, Gyrinus natator, Chironomus thummi, Aedes aegypti Cheoborus crystallinus, Corixa punctata, and Piona carnea) was determined in the laboratory using 24-h static water tests. The 24-h EC₅₀ values (based on reduced motility) ranged from 0.02 μg·l^?1for A. aquaticus and P. carnea to 2 μg·l^?1 for D. magna, and for seven of the species the EC₅₀ values were < 0.1 fig μg·l^?1 The 24-h LC₅₀values for G. natator, C. thummi, and C. punctata were > 5 μg·l^?1 For the seven more susceptible species the 24-h LC₅₀values ranged from 2 μg·l^?1 to 0.05 μg·l^?1The acute toxicity of cypermethrin to some species of fish (Cyprinus carpio. Scardinius erythrophthalmus, Salmo gairdneri, Salmo trutta and Tilapia nilotica) was determined using 96-h continuous-flow tests. The 96-h LC₅₀ values obtained were within the range 0.4–2.2 μg·l^?1.The solubility of cypermethrin within the range of test temperatures (15–25°C was estimated to be in the range 5–10 μg·l^?1.