Assessment of chromosomal damage induced by a deltamethrin-based insecticide in fish (Anguilla anguilla L.) - a follow-up study upon exposure and post-exposure periods.

ABSTRACT

The pyrethroid insecticide Decis®, containing deltamethrin as active ingredient, is among the most popular broad-spectrum biocides, with wide application in agriculture and home pest control. The occurrence of deltamethrin in the aquatic environment is well-established, but the possible genotoxic effects of Decis® in non-target organisms, namely fish, remain unknown. Hence, this work aimed to evaluate the cytogenetic damaging potential of Decis® in European eel (Anguilla anguilla L.), adopting the erythrocytic nuclear abnormalities (ENAs) assay. In addition, it was intended to investigate the damage progression in the post-exposure period. The frequency of immature erythrocytes (IE) was also determined to provide indirect information on the erythrocyte catabolism and erythropoiesis rate. Fish were exposed to 17.5 and 35 µg L(-1) of Decis® (equivalent to 0.05 and 0.1 µg L(-1) of deltamethrin, respectively) during 1 and 3 days. Thereafter, fish were transferred to clean water and kept for 1, 7 and 14 days. The results demonstrated a clear potential to induce chromosomal damage following 3 days exposure, depicted in an ENA frequency increase for both Decis® concentrations. The transient nature of this cytogenetic damage was also demonstrated, as ENA frequency returned to the control level 1 and 7 days after cessation of the exposure, respectively for the higher and the lower Decis® concentration. Moreover, this response pattern suggested a rapid metabolization and elimination of the formulation constituents by A. anguilla, combined with an increased erythrocyte turnover in fish exposed to the higher Decis® concentration, as pointed out by the IE frequency rise. Overall, the demonstrated genotoxic properties of Decis® pointed out increased risk factors to fish exposed to this insecticide.