The Toxicity Study Of Pesticide Adjuvants To Daphnia Magna

Pesticide adjuvants are the generic term for pesticide formulation additives except activeingredients in processing and application. Some pesticide adjuvants show different toxicitiesto humans, beneficial organisms and the environment. However, the toxicities of mostpesticide adjuvants to aquatic organisms are unknown. Daphnia magna is one of therepresentative invertebrate aquatic organisms, which is the primary metabolism organism ofthe aquatic food chain, connecting producers and secondary consumers and is very sensitiveto environmental contaminants entered into the aquatic environment. Therefore, in order tomake sense of the safety of common pesticide adjuvants comprehensively and systematically,in this paper we choosed D. magna as test material and investigated the acute toxicity ofcommon organic solvents and pesticide surfactants. Meanwhile, the chronic and embryotoxicity of the organic silicon Breakthru S240to D. magna were also determined. The abovetests provided theoretical basis for choosing appropriate pesticide adjuvants.1. The acute toxicities of14organic solvents such as acetone, dimethyl benzene andsoybean oil to D. magna were investigated according to the standard test method namelyOECD. The majority of the tested organic solvents showed low acute toxicity to D. magna.The toxicity of acetone was the lowest with EC50value of2618.678mg/L after48hours，while methyl oleate is the highest and the value of EC50was4.493mg/L.2. The acute toxicities of39common nonionic,6anionic and3cationic surfactants to D.magna were also determined. The results indicated that the acute toxicities of three cationicsurfactants,1227,1427and C8-10, to D. magna belongs to virulent and the toxicity of1427was highest with EC50value of0.97210-2mg/L after48hours. The toxicities of nonionicsurfactants polyoxyethylene ether castor oil EL, tween and span emulsifiers belong to lowtoxicity, but the toxicity levels of alkylphenol polyoxyethylene ether and fatty alcoholpolyoxyethylene ether surfactants were relative higher, of which AEO-7and AEO-5displayed high toxicity with EC50value of0.818mg/L and0.974mg/L respectively. In thosetwo types of surfactants, the more liposolubility and the higher toxicity it is. Most of anionicsurfactants are medium toxicity, but the acute toxicity of NNO belongs to high toxicity withEC50value of0.166mg/L.3. The48h-LC50value of the organic silicon adjuvant Breakthru S240to D. magna was1.218mg/L, which belongs to the medium toxicity. The values of LC50decreasedsignificantly with the extension of exposed time. The organic silicon adjuvant hassignificantly effect on the breeding, the length and the sex differentiation, and the efficiency was more evident with the increase of concentration. The sequence of all biologicalindicators’ sensitivity is as follows, the offspring of the third brood> the total offspring> theoffspring of the first brood, the sex differentiation> the length, the broods and molts> thesurvival rate> the time of the first and third pregnancy. The impact was not obvious to F1(1st)after F0exposed to Breakthru S240. But it still showed significant differences forreproduction of F1(3rd) compared with the control group. The fecundity of treatment groupwas decreased and the breeding time postponed nearly two days later than the control group.In addition, the organic silicon adjuvant had potential hazard to the development of embryo ofD. magna and the inhibition rate reached to68.50%. The main toxic traits include larvalcurved or unextended shell spine and undeveloped antenna.