Ecotoxicology of lindane and deltamethrin in aquatic environments
The persistence in water (in the presence or in the absence of sediment), the acute toxicity and the bioconcentration capacities of lindane and of deltamethrin were studies under laboratory conditions. There is a signifiant decrease in the persistence in water of bath insecticides, when there is sediment in water. Nevertheless, deltamethrin is much less persistent in water than lindane, both in the presence and in the absence of sediment. Studies of acute toxicity showed that the toxicity of deltamethrin is about 100 to 1 000 times greater than that of lindane. The five species studied were similarily sensitive to the two insecticides. Two methods of contamination were used in the bioconcentration studies (spot and flow through system contamination). Under both conditions and for all the species tested, the concentration factor of lindane was always greater than that of deltamethrin. Its relatively significant persistence in water, its desorption from sediment, its low acute toxicity and high bioconcentration capacities indicate that the ecotoxicological risk of lindane is mainly due to its chronic toxicity and biocaccumulation through trophic food chains. On the contrary, the rapid disappearance of deltamethrin from water, its high adsorption on sediment and its low bioconcentration capacities indicate that this molecule will not accumulate through trophic chains. Nevertheless, its extreme toxicity and rapidity of action may cause significant harm to limnic ecosystems alter direct treatment.