Environmental concentrations of agricultural-use pesticide mixtures evoke primary and secondary stress responses in rainbow trout.
ABSTRACT The present study sought to determine whether environmentally realistic mixtures of agriculturally important pesticides are stressful to fish. Juvenile rainbow trout were exposed for 96 h to concentrations of a pesticide mixture found in a waterway that is the focus of salmon restoration efforts (Nicomekl River, BC, Canada). This mixture contained organochlorine, organophosphorus, phenylurea, and triazine classes of pesticides. Fish given a realistic mixture exposure (total concentration, 1.01 µg/L) had increased plasma cortisol concentration, packed red cell volume, hematocrit (Hct), as well as decreased white cell volume, leukocrit (Lct). Similar changes in Hct and Lct were apparent after exposure to a lower concentration (0.186 µg/L). Interestingly, no changes in plasma cortisol concentration, Hct, or Lct were noted after exposure to a higher concentration (13.9 µg/L). This suggests that the exposure likely impaired the mechanisms enabling the stress response. Across all exposures, plasma glucose concentration was related to plasma cortisol concentration, not to pesticide mixture concentration. This suggests that a secondary stress response may be more related to variability in individual primary stress response than to differences in pesticide exposure concentrations. In summary, the present study indicates that salmon living in agrichemical-contaminated waterways may be experiencing stress, and this may pose a threat to their survival.
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ABSTRACT: Laboratory tests were conducted in order to investigate the effects of individual and binary-combined commercial insecticides endosulfan, temephos, malathion and pirimiphos-methyl on the earthworm Eisenia andrei. The effects of individual insecticides were determined by measuring the activities of acetylcholinesterase (AChE), catalase (CAT) and glutathione-S-transferase (GST). After exposure to studied insecticides, dose-dependent decrease in AChE activity and dose-dependent increase in CAT activity was recorded. The activity of GST was without consistent dose-response reaction, but generally the investigated insecticides caused the increase in GST activity. In order to determine the effects of binary-combined mixtures, and interactions between the components in the mixture, the relationship between effective concentration of AChE inhibition for mixture and effective concentration of AChE inhibition for each component in the mixture was investigated. The obtained results showed additive effect for mixtures endosulfan+malathion; endosulfan+pirimiphos-methyl; temephos+malathion and temephos+pirimiphos-methyl, synergistic effect for mixture endosulfan+temephos and in the case of mixture malathion+pirimiphos-methyl the antagonistic effect was indicated.Environmental toxicology and pharmacology. 07/2013; 36(2):715-723.
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ABSTRACT: The transfer of eleven phenylurea herbicides through soil columns was investigated in laboratory conditions in order to determine leaching properties in a calcareous soil. Elution curves with distilled water were plotted after herbicide application on the soil column. Phenylurea retention by the soil indicating interactions with soil can be classified as follows: fenuron < fluometron ≤ isoproturon = monuron < metoxuron < monolinuron < metobromuron < chlorotoluron < linuron = diuron < chlorbromuron. The number and nature of halogen atoms on the phenyl ring had an important influence on leaching. Retention was higher for molecules with higher number of halogen, and it was also higher for bromine than chlorine. Column elution experiments were compared to batch experiments from which the distribution coefficients K (d) were determined. According to Kendall correlation coefficients, parameter m/m (0max) from column experiments was relatively well linked to K (d). In case of phenylurea, a linear relationship between K (d) and m/m (0max) was established.Environmental Science and Pollution Research 10/2012; · 2.62 Impact Factor
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ABSTRACT: The adsorption of 12 pesticides of the phenylurea family was studied by batch experiments in order to determine the adsorption coefficient, K d. The study was conducted in two soils chosen for their differences in organic matter and calcite contents. K d pesticide adsorption coefficients were higher for soil S1 than for soil S2 due to the presence of a higher organic matter content and a lower calcite content in soil S1. To identify pesticide properties governing retention, 18 molecular descriptors were considered. Class-specific quantitative structure-property relationship (QSPR) soil sorption models using one, two, and three descriptors were developed from our experimental data using linear regressions. One of the aims of this work was to check whether QSPR models that did not include literature values of K ow were able to predict K d coefficients in satisfactory agreement with our experimental data. The influence of the level of theory in determining K ow and polarisability predictors on the predictive performance of the model was also examined by comparing quantum chemistry and empirical (QikProp) approaches. The one-descriptor model using "quantum" polarisability α was found to perform almost as well as or better than the other models.Environmental Science and Pollution Research 04/2013; · 2.62 Impact Factor