Risk of chlorine dioxide as emerging contaminant during SARS-CoV-2 pandemic: enzyme, cardiac, and behavior effects on amphibian tadpoles

PELTZER, PAOLA M.; CUZZIOL BOCCIONI, ANA P.; ATTADEMO, ANDRÉS M.; MARTINUZZI, CANDELA S.; COLUSSI, CARLINA L.; LAJMANOVICH, RAFAEL C.

Toxicology and Environmental Health Sciences

ELSEVIER

Año: 2022

2005-9752

AbstractObjective The use of chlorine dioxide (ClO2) increased in the last year to prevent SARS-CoV-2 infection due to its use asdisinfectant and therapeutic human treatments against viral infections. The absence of toxicological studies and sanitaryregulation of this contaminant represents a serious threat to human and environmental health worldwide. The aim of thisstudy was to evaluate the acute toxicity and sublethal effects of ClO2on tadpoles of Trachycephalus typhonius, which is acommon bioindicator species of contamination from aquatic ecosystems.Materials and methods Median lethal concentration (LC50), the lowest-observed effect concentration (LOEC), and the noobservedeffect concentration (NOEC) were performed. Acetylcholinesterase (AChE) and glutathione-S-transferase (GST)activities, swimming behavior parameters, and cardiac rhythm were estimated on tadpoles of concentrations ≤ LOEC exposedat 24 and 96 h. ANOVA and Dunnett?s post-hoc comparisons were performed to define treatments significance (p ≤ 0.05).Results The LC50 of ClO2was 4.17 mg L−1 (confidence limits: 3.73?4.66). In addition, NOEC and LOEC values were 1.56and 3.12 mg L−1 ClO2,respectively, at 48 h. AChE and GST activities, swimming parameters, and heart rates increasedin sublethal exposure of ClO2(0.78?1.56 mg L−1) at 24 h. However, both enzyme activities and swimming parametersdecreased, whereas heart rates increased at 96 h.Conclusion Overall, this study determined that sublethal concentrations of ClO2produced alterations on antioxidant systems,neurotoxicity reflected on swimming performances, and variations in cardiac rhythm on treated tadpoles. Thus, our findingshighlighted the need for urgent monitoring of this chemical in the aquatic ecosystems.