RESUMEN
Data concerning the toxicity of the transformation products of some pesticides considered emerging contaminants are still incipient. This study aimed to evaluate acute (filter paper contact and avoidance test) and chronic (assays carried out in Red yellow Ultisoil) effects of the transformation products of the fungicide imazalil (IMZ) by heterogeneous photocatalysis (TiO2/UV) in Eisenia andrei. Some endpoints, i.e. biomass variation, disorder in reproduction and avoidance behavior, cytotoxicity (cell density and feasibility), and coelomic fluid (eleocytes and amoebocytes, immune cell) and antioxidant system (catalase (CAT) and glutathione S-transferase (GST)) changes were assessed. The studied degradation times (6, 18, 35 and 90 min) represented 70; 35; 10 and 0% of the initial IMZ concentration (5 mg L-1). No lethality and no significant difference in biomass variations were noted in the acute contact test. Decreased GST and increased CAT activities, as well as cell typing alterations and decreased cell viability and density detected at the 90-min degradation timepoint (PDT-90) indicate direct cytotoxic IMZ transformation product effects. In the avoidance test, no significant earthworm repulsion or attraction was observed. PDT-90 transformation products were responsible for losses in biomass and a reduction in the number of earthworm cocoons and juveniles present in soil. No cytotoxic effects were observed in the long term, although increased CAT and decreased GST activities were observed. Investigations on the relative toxicity of IMZ transformation products are relevant for future discussions regarding the environmental treatment, control and destination of this compound and its derivatives.
Asunto(s)
Oligoquetos , Contaminantes del Suelo , Animales , Imidazoles , Suelo , Contaminantes del Suelo/análisis , Contaminantes del Suelo/toxicidadRESUMEN
Although considered an emerging contaminant and detected in the environment, the systematic and penetration fungicide imazalil ((RS)-1-(ß-allyloxy-2,4-dichlorophenylethyl) imidazole) has received relatively little scientific attention with regard to its possible negative effects in the environment. Only a few toxicological studies have assessed the potential environmental effect of imazalil and its impact on organisms. In this context, the aim of the present study is to evaluate the effects of different concentrations of the pesticide imazalil on the earthworm Eisenia andrei in acute contact and chronic tests in natural soil. Moreover, several endpoints, such as biomass loss or gain, reproduction, behavior, effects on immune system cells, and oxidative stress were also evaluated. Imazalil toxicity to E. andrei was determined by three approaches: a filter paper contact test (0, 0.16, 1.66, 16.6, 166 µg.cm-2), an avoidance (0, 0.1, 1, and 10 mg.kg-1), and a chronic test for 45 days (0, 0.01, 0.1, 1, and 10 mg.kg-1). All organisms exposed to the filter paper contact and chronic tests were submitted to two endpoint analyses: first, coelomic fluid collection by the extrusion method to determine density, viability, and cell type; second, oxidative stress assessments by determining GST and CAT enzymatic activities. This study allows for the conclusion that imazalil does not cause immediate earthworm death after exposure (LC50 > 166 µg.cm-1). However, due to several complementary factors, this compound may compromise earthworm health and lead to death, as E. andrei individuals did not avoid the contaminated soil, thus contributing to longer exposure periods and consequent cumulative damage to their systems. Decreased immunocompetent cellular viability (p < 0.05) and density (p < 0.05) in the chronic test are noteworthy, leading to susceptibility to exogenous factors, as well as irreversible cellular damage provoked by oxidative stress, such as cellular membrane rupture.