Atrazine bioconcentration in Cnesterdon decemmaculatus.

MARIA FLORENCIA NUÑEZ CRESTO; MANUEL FLORES; CRISTINA PÉREZ-COLL; GABRIELA SVARTZ

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting.; 2023

SETAC LA

The pollution of the aquatic environments due to the agricultural expansion is a growing concern since the last few decades. Many pesticides have been banned as a result of numerous studies showing its toxicity and persistence. Atrazine is an herbicide from the triazine family that has been proven to cause endocrine disruption, malformations and mortality in different aquatic organisms. Even though it has been prohibited by the European Union, it is still used by several countries, including Argentina, and it can be found in multiple water bodies. Cnesterodon decemmaculatus, also knowns as ten spotted live-bearer, is a fish that can be commonly found in aquatic environments, and it is used as a test species due to its sensitivity and availability. The goal of this study was to evaluate the bioconcentration of atrazine in C. decemmaculatus. To achieve this, semistatic standardized laboratory bioassays were carried out on adult fish, which were exposed to 4 concentrations between 0.5 and 10 mg active ingredient (a.i.)/L of a commercial formulation of atrazine (Atramyl 90 WG®) for a subchronic period of time (336 h). Each treatment was performed by triplicate and simultaneous controls with dechlorinated water were maintained. Once the exposure period finished, the organisms were sacrificed, homogenized and processed to measure the concentration of herbicide in their tissues using HPLC coupled with a tandem quadrupoles mass spectrometer. Atrazine levels in the control group were below the detection limit. Within the exposure range, the concentration of herbicide in the tissues increased with the exposure concentration, showing a significant growth in 10 mg/L regarding the lowest treatment (0.5 mg/L). The coefficient between the amount of atrazine in the tissues and its availability in the exposure tanks was higher than 1, meaning that the organisms kept incorporating the contaminant with each water renewal. Further studies must be held in order to be able to determine the bioconcentration factor, which can later be used to establish a biomagnification potential. This is relevant because the accumulation of pesticides in lower levels of the food webs can impact and biomagnify in upper levels, causing a risk for the populations of the aquatic organisms.