Avaliação do efeito tóxico de cobre oriundo de aplicação de calda bordalesa em produção orgânica de laranjas e uvas

Abstract

Currently, organic products have gained attention for its nutritional quality, food safety and sustainability in its production. Organic farming uses copper-based fungicides such as a Bordeaux mixture, which is composed of hydrated lime and copper sulfate. Copper is a natural and essential chemical element for living organisms, but there are controversies regarding the effects on the environment and human health. Thus, the objective of this study was to evaluate the copper content in soils, orange and grape juice of an organic property that uses the Bordeaux mixture as fungicide, and from the concentrations found, to evaluate the effects of acute and chronic exposure on Caenorhabditis elegans nervous system. The study started from the collection of soil and fruit, after harvest were extracted the orange and grape juices. Subsequently, the copper concentrations in soil and in the juice were analysed by Atomic Absorption Spectrometry Plasma Argon. After determination of the copper concentration in the juices, the C. elegans were divided into five groups, the control group received ultrapure water, and treated with copper received the 0.05 mg/L, 0.1 mg/L, 0.3 mg/L and 0.7 mg/L. After the exposure, behavioral and enzymatic parameters of wild strains of C. elegans were evaluated. The trials of acute and chronic exposures of C. elegans to copper showed that there were changes in acetylcholinesterase activity. In the acute exposure doses of 0.05 mg/L, 0.1 mg/L and 0.7 mg/L activated the enzyme, a similar result was found after chronic exposure at doses 0.3 mg/L and 0.7 mg/L. Doses of 0.05 mg/L and 0.1 mg/L inhibited the enzyme after chronic exposure. Exposed organisms also showed behavioral changes, such as reduction in pharyngeal beats to acute exposure at a dose of 0.05 mg/L and 0.7 mg/L on chronic exposure and increase in the defecation cycle at doses of 0.1 mg/L and 0.3 mg/L on acute exposure and reduction on chronic exposure at 0.3 mg/L. As expected, copper levels were increased in soils that received the copper-based fungicide, the same was found for juices. However, it was observed that the doses found in the juices promoted significant changes in the cholinergic system, which had repercussions on the behavior of the worms. Thus, it is recommended major criterion for the application of Bordeaux mixture, considering that copper metal has to be a potential for bioaccumulation in biological systems.