Toxicity of copper oxide nanoparticles and CuCl2·2H20 salt on embryo-larval development of Rhinella arenarum

VALENTINA AMABLE; MERCEDES ACQUARONI; SOLEDAD PÉREZ CATÁN; CRISTINA PÉREZ-COLL; GABRIELA SVARTZ

Montevideo

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

SETAC LA

The release in environment of emergent contaminants as nanoparticles (NPs) and the respective salts use in their synthesis, has drawn considerable attention which has become an eminent area of research to understand the potential risk related to their short- and long-term toxicity. In this sense, the aim of this work was to evaluate the toxicity of copper oxide NPs (CuO-NPs) and compare it with its respective salt (CuCl2·H20) in the early development of a native amphibian, Rhinella arenarum, by acute and chronic standardized bioassays (AMPHITOX). Lethality and sublethal effects such as developmental, morphological and ethological alterations were assessed in embryos and larvae exposed to different concentrations in the range: 0.001-100 mg/L CuO-NPs, and 0.001-10 mg/L CuCl2·2H20 up to 21 days. The bioassays were semi-static with replacement of the solutions every 48 h; treatments were done by triplicate, and a control group without exposure was simultaneously maintained. The results show that, in both developmental periods, the salt caused higher toxicity than CuO-NPs with LC50-96 h values of 0.080 and 1.26 mg/L for embryos respectively. The difference in toxicity between NPs and salt could be due to both structural and physicochemical characteristics that influence on bioavailability and toxicity. Moreover, toxicity increased with exposure time in all cases (NOEC-504 h for larvae=0.5 mg/L for CuCl2·2H20 and 10 mg/L for CuO-NPs), with a greater sensitivity during the embryonic period (NOEC-504 h for embryos= 0.01 mg/L for CuCl2·2H20 and 0.1 mg/L for CuO-NPs). Regarding sublethal effects, exposed embryos from 0.001 mg/L to both substances exhibited several alterations such as persistent yolk plugs, cell dissociation, developmental delay, edemas, severe malformations, underdeveloped gills and tails, agenesis and/or curvature of tails and microcephaly. In the chronic and subchronic exposure periods, embryos and larvae presented spasmodic contractions and weak movements. Taking into account the exponential growth in production and use of these substances it is expected that their levels of contamination by these chemical agents increase considerably and that wildlife, particularly amphibians, will be more exposed and their populations will eventually be at risk.