Modeling and prediction for the acute toxicity of pesticide mixtures to thefreshwater luminescent bacterium Vibrio qinghaiensis sp.-Q67
Xuefei Zhou , Wenjing Sang , Shushen Liu , Yalei Zhang , Huilin Ge
DOI:
Received May 30, 2009,Revised October 26, 2009, Accepted , Available online
Volume 22,2010,Pages 433-440
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In China, water pollution by pesticide mixtures has constituted a serious environmental problem due to potential toxicity and
bioaccumulation. But few pesticide combinations have exactly similar and dissimilar mechanisms of action. For this purpose, in
tests with the freshwater luminescent bacterium (Vibrio qinghaiensis sp.-Q67), ten pesticides, including three herbicides and seven
insecticides, were selected as test substances. Concentration response analysis was performed for ten individual substances, and for
mixtures containing all ten substances in twelve di erent concentration ratios (based on UDCR and EECR methods). The observed
mixture toxicity was compared with predictions by the two models, concentration addition (CA) and independent action (IA). The
toxicity of the tested mixtures showed a good agreement with those predicted by the concept of CA except four UDCR mixtures:
UD10-2, UD10-4, UD10-8 and UD10-10. To examine the influence of imidacloprid in the four UDCR mixtures (UD10-2, UD10-4,
UD10-8, UD10-10), it was removed from the ten-pesticide mixtures and the remaining nine chemicals were combined at the same
relative proportions based on the UDCR method (UD9-2, UD9-4, UD9-8, UD9-10). There was not significant departure from CA for
the scattered points with the nine remaining pesticides omitting imidacloprid. Thus, imidacloprid may significantly influence the other
pesticides due to its properties.
