Bioaccumulation and distribution behavior of endosulfan on a cichlid fish: Differences between exposure to the active ingredient and a commercial formulation.

LO NOSTRO, FABIANA LAURA; MIGLIORANZA, KARINA S.B.; DA CUÑA, RODRIGO HERNÁN; ONDARZA, P; SHIMABUKURO, V

ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY

SETAC PRESS

Lugar: Pensacola; Año: 2019 vol. 39 p. 604 - 611

0730-7268

Organochlorine pesticides, like other persistent organic pollutants, reach aquatic ecosystems during application and are able to bioconcentrate and biomagnificate through the food chain due to their lipophilic nature. Even though agricultural and urban use involves commercial formulations (CFs), toxicological studies focus almost exclusively on the active ingredients (AIs) of pesticides. Toxicity of AIs and CFs can differ due to additive or synergistic effects of non-specified ?inert? ingredients. The intensive use of the organochlorine pesticide endosulfan (ES) as a wide range insecticide in crops of high commercial value over the last few decades make it one of the most frequently detected contaminants in the aquatic environment, even after it has been restricted or banned worldwide. Therefore, the aim of this study was to evaluate the bioaccumulation and organ distribution of waterborne ES after acute exposure, comparing between the AI and a CF using adult males of the freshwater fish Cichlasoma dimerus, perciform species representative of the La Plata River basin. Male fish were exposed to a nominal concentration of 0.7 g L-1 ES, either the AI or in a CF, for two weeks under semi-static conditions. Liver, testes, gills, brain and dorsal skeletal muscle samples were collected for ES extraction and quantification by GC-ECD. Results suggest a rapid metabolization of ES isomers to the metabolite sulfate (ES-S) in fish tissues, since isomers were present in highest amounts in gills, indicative of recent uptake, and ES-S levels were highest in most organs. When fish were exposed to the AI, there was a positive correlation between lipid % and ES-S levels. Upon CF exposure no correlation was evident, indicating that the presence of adyuvants alters ES distribution; a higher uptake and mobilization of b-ES due to the presence of adjuvants could also be inferred in gills and liver, respectively. As toxic effects of pollutants are expressed when distributed to a site of action, differences in organ distribution of ES between a CF and the AI alone may alter toxicity. Therefore, additives used in formulations cannot be considered inactive even when they exhibit no toxicity on their own.