A comparative study of the acute toxicity of the herbicide atrazine to cladocerans Daphnia magna, Ceriodaphnia silvestrii and Macrothrix flabelligera Um estudo comparativo da toxicidade aguda do herbicida atrazina aos cladóceros Daphnia magna, Ceriodaphnia silvestrii e Macrothrix flabelligera Abstract: Aim: In this study we compared the sensitivity of three species of Cladocera, Daphnia magna, Ceriodaphnia silvestrii and Macrothrix flabelligera, to the commercial product of the herbicide Atrazine, the Atrazine Atanor 50 SC® (500 g/L), widely used on crops in Brazil. Methods: Acute toxicity tests were performed at the nominal atrazine concentrations 2. 25, 4.5, 9.0, 18.0, 36 and 72 mg L -1 , on C. silvestrii and M. flabelligera and at 2. 25, 4.5, 9.0, 18.0, 36, 72 and 144 mg L -1 on D. magna. The range of concentrations tested was established in a series of preliminary tests. Results: The toxicity tests showed that the two species naturally occurring in water bodies in Brazil were more susceptible than Daphnia magna. The effective concentrations of Atrazine Atanor 50 SC® (EC 50 -48 h) to the species M. flabelligera, C. silvestrii and D. magna were 12.37 ± 2.67 mg L -1 , 14.30 ± 1.55 mg L -1 and 50.41 ± 2.64 mg L -1 , respectively. Furthermore, when EC 50 observed here for M. flabelligera and C. silvestrii were compared with published values of EC 50 or LC 50 (mg L -1 ) for various aquatic organisms exposed to atrazine, it was seen that these two cladocerans were the most sensitive to the herbicide. Conclusions: Considering these results and the broad distribution of C. silvestrii and M. flabelligera in tropical and subtropical regions, it is concluded that these native species would be valuable test organisms in ecotoxicological tests, for the monitoring of toxic substances in tropical freshwaters. Resumo: Objetivo:Neste estudo comparamos a sensibilidade de três espécies de cladóceros, Daphnia magna, Ceriodaphnia silvestrii e Macrothrix flabelligera quando expostas ao herbicida Atrazina Atanor 50 SC® (500 g/L), amplamente utilizado em plantações no Brasil. Métodos: Foram realizados testes de toxicidade aguda das concentrações nominais de atrazina nos valores de 2,25; 4,5; 9,0; 18,0; 36 e 72 mg L -1 para C. silvestrii e M. flabelligera e de 2,25; 4,5; 9,0; 18,0; 36; 72 e 144 mg L -1 para D. magna. Estas faixas de concentrações foram estabelecidas em testes preliminares. Resultados: Os testes de toxicidade mostraram que as duas espécies que ocorrem naturalmente nos corpos d'água do Brasil foram mais sensíveis do que Daphnia magna. As concentrações efetivas de Atrazina Atanor 50 SC® (CE 50 -48 h) para M. flabelligera, C. silvestrii e D.magna, foram 12.37 ± 2.67 mg L -1 , 14.30 ±1.55 mg L -1 e 50.41 ± 2.64 mg L -1 , respectivamente. Comparando-se os valores de CE 50 da atrazina obtidos para M. flabelligera e C. silvestrii com valores de CE 50 ou CL 50 (mg L -1 ) disponíveis na literatura para diferentes organismos aquáticos observa-se que os cladóceros testados foram mais sensíveis ao herbicida do que os demais. Con...

Air pollution is currently considered as one of the greatest health risks for humans and air pollution legislation and control worldwide is based on the size of particulate matter (PM) to than larg of atmospheric PM after transfer to an aqueous system. We aimed to understand the changes in the physical properties and characteristics that can contribute to increased metal uptake in humans and other biota to improve the safety regulations involving PM in the environment.Samples collected in an area affected by the steel industry influence were separated into 8 iameter light scattering (DLS), potential zeta and nanoparticle tracking analysis (NTA) for dispersion measurements and scanning electron microscope (SEM) for particle size characterization. The elemental composition (B,

As compared to their temperate counterparts, few toxicity tests have been conducted so far into the evaluation of the sensitivity of indigenous tropical species to pesticides. Especially mixture toxicity assessments appear to be scarce. To contribute to increase our knowledge in this arena, we evaluated the acute toxicity of diuron and carbofuran and their mixtures to the neotropical oligochaetes Allonais inaequalis and Dero furcatus, and the ostracod Strandesia trispinosa. Tests were performed with both the pure active ingredients, as well as their formulated products. The toxicity of the latter to the three test organisms was generally greater than that of the pure active ingredients, although absolute differences were rather small. The sensitivity of the indigenous species was slightly greater than temperate test species from the same taxonomic groups. The concentration addition conceptual model best described the results of the mixture toxicity data. Derived deviations of this model appeared to be dependent on the test organism and as to whether the pesticides were applied as active ingredients or their commercial products. Reported field concentrations of the two pesticides indicate risks to freshwater biota, especially if they are both present. The test species used in the present study are concluded to be suitable candidates as surrogate test organisms in local pesticide risk evaluations.

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In this study, the effects of exposing the rotifer Philodina roseola to the pesticide carbofuran were investigated. Its range of sensitivity to potassium dichromate, the acute toxicity of active ingredient carbofuran and of carbofuran dosed as its commercial form, Furadan(®) 350 SC were determined. Chronic toxicity of carbofuran dosed as Furadan(®) 350 SC on P. roseola survival and fecundity were also studied. The sensitivity of P. roseola to K2Cr2O7 ranged from 29.52 to 64.67 mg L(-1), averaging 47.10 mg L(-1). The 48-h EC50 were 13.36 ± 2.63 mg L(-1) for carbofuran and 89.32 ± 6.52 mg L(-1) for commercial form. Chronic toxicity tests showed that the survival of this rotifer was not affected by the carbofuran dosed as Furadan(®) 350 SC at the concentrations tested and that at 1.56 and 3.12 mg L(-1) their fecundity was higher than in the absence of this commercial product, characterizing the hormesis phenomenon. The sensitivity profile of several species to carbofuran indicated that P. roseola is more susceptible to this pesticide than the fish Clarias batrachus, the bacterium Vibrio fischeri, the protozoan Paramecium caudatum and the rotifer Brachionus calyciflorus, although the acute toxicity of carbofuran dosed as Furadan(®) 350 SC to P. roseola is much lower than that of active ingredient carbofuran. The results also imply that the exacerbated use of pesticides and the constant, accelerated expansion of agricultural activity will make aquatic non-target species even more vulnerable. Furthermore, the relevant role of benthic organisms in aquatic environments justifies the inclusion of P. roseola and other benthic species in toxicity screening for risk assessment, regarding this environmental compartment.

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