農薬の水生動物に対する毒性試験法の確立

抄録

“The standard method for the evaluation of acute toxicity of pesticides to fish” and “A method for the evaluation of acute toxicity of pesticides to daphnids” were established to give 48h TLm values for carp and 3h TLm values for Daphnia pulex or Moina macrocopa. With these and some modified methods, acute toxicity of all the already registered pesticides to carp and daphnids were evaluated, and factors influencing the toxicity of pesticides or sensitivity of test organisms to pesticides were investigated. The results are summarized as follows: (1) Rotenone and organochlorine insecticides, organomercurial, organotin, dimethyl dithiocarbamate and phthalimide fungicides, dinitrophenol and pentachlorphenol herbicides have high toxicity to carp, while organophosphorus and phenylcarbamate insecticides are extremely toxic to daphnids. (2) In general, emulsifiable concentrates, technical products, wettable powders, dust and granules are toxic to carp, in this order. (3) The majority of pesticides are more toxic to carp and daphnids at higher temperatures, but some, including folpet and DDT, are less toxic to carp and daphnids, respectively, at higher temperatures. (4) The majority of pesticides are less toxic at higher pH. (5) No apparent synergism or antagonism is observed to occur between 6 pairs of organophosphorus and phenyl carbamate insecticides with carp. (6) No remarkable change in sensitivity of carp is observed with growth to 6 pesticides, including organophosphorus insecticides and pentachlorphenol herbicide, although sensitivity to endosulfan insecticide is extremely high at earlier developmental stages after floating. (7) Dietary pesticides are in general less toxic to carp than pesticides in bath exposure systems. In addition, sensitivity of other aquatic organisms to pesticides was evaluated by the recently developed method. Results are summarized as follows: (1) Gold fish, tanago; Rhodeus moriokae, dojo; Misgurnus anguillicaudatus, and medata; Oryzias latipes, have sensitivity similar to carp. (2) Larvae of dragonfly; Orthetrum albistylum speciosum, and mayfly; Cloëon dipterum, are found to have lower sensitivity than daphnids, but the correlations of TLm values among them are comparatively high. (3) The molluscean animals, Indoplanorbis exustus, Cipangopaludina chinensis malleata, Semisulcospira libertine and Physa acuta have low sensitivity to pesticides in general. (4) Tadpoles of Bufo bufo japonicas, Rana brevipoda and Rana catesbeiana have low sensitivity to pesticides in general.