Antioxidant system alterations, oxidative, and genotoxic effects in Danio rerio (zebrafish) exposed to leachate from a dumpsite.

Water body contamination by leachate originated from dumpsites is a concern for municipal solid waste (MSW) management. In this context, this study aimed to evaluate antioxidant system alterations and oxidative and genotoxic effects in Danio rerio (zebrafish) exposed to leachate from a closed dumpsite. Groups comprising 50 fish were exposed (96 h) to different leachate concentrations (5, 15, 30, and 50%) to evaluate effects on liver and brain superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST) activities and reduced glutathione (GSH) and metallothionein (MT) concentrations, as well as malondialdehyde (MDA) and protein carbonylation (PTC) levels. Blood genotoxicity was evaluated by the comet assay. The investigated dumpsite leachate pond presented high chloride concentrations (Cl-; 2288.4 ± 69.5 mg L-1) and high electrical conductivity (EC; 8434.0 mS cm-1), indicating the presence of leachate. Concerning Danio rerio exposure, higher SOD (37%), CAT (67%), and GST (39%) activities and higher GSH (57%) concentrations were observed in liver following exposure to 50% leachate, while decreased brain GST (42%) activities and GSH (90%) levels were observed at the same leachate concentration. A significant increase in the olive tail moment (OTM; 280%) indicative of genotoxicity in blood was observed. A principal component analysis indicated that increased enzymatic activities and high levels of both GSH and MT were not sufficient to prevent the accumulation of reactive oxygen species, resulting in PTC and genotoxicity. Therefore, leachate exposure causes sublethal Danio rerio effects, altering the antioxidant system, increasing ROS production, and leading to PTC and genotoxicity. The findings demonstrate the need to further develop sublethal level assessments in zebrafish using leachate from different sources to subsidize risk assessments regarding MSW management.

Oxidative stress and metal homeostasis alterations in Danio rerio (zebrafish) under single and combined carbamazepine, acetamiprid and cadmium exposures.

Contaminants of emerging concern (CEC) are routinely detected in aquatic environments, especially pharmaceuticals, such as carbamazepine (CBZ), and neonicotinoid pesticides, like acetamiprid (ACT). CECs can interact with each other and with other legislated contaminants like Cd, resulting in unknown effects. Most studies evaluate only the effects of single contaminant exposures on aquatic biota. Therefore, the aim of the present study was to assess the effects of both single and combined CBZ, ACT and Cd exposures on zebrafish brain and liver oxidative stress parameters and metal homeostasis. The biomarkers catalase (CAT), glutathione-S-transferase (GST), total thiols (TOT), metallothionein (MT) and malondialdehyde (MDA) and the essential elements Ca, Cu, K, Na, Mg, Mn and Zn were evaluated after 96-hour static exposures. CBZ, ACT and Cd single (brain and liver) and combined (liver) treatments resulted in oxidative effects in both fish organs, also leading to metal (Ca, Mg, K, Mn, Zn and Cu) homeostasis alterations. ACT exposure resulted in the greatest adverse effects in the brain, while CBZ was the cause of major element homeostasis and oxidative stress alterations in the liver. Lower LPO levels were observed in the combined treatments compared to single treatments, suggesting interactions and contaminant effect attenuation. This study is the first to evaluate the initial effects of combined CBZ, ACT and Cd exposures in zebrafish, paving the way for further investigations concerning other biomarkers during longer exposure times.

Antioxidant system alterations and biological health status of earthworms following long-term exposure to antibiotic-contaminated poultry litter.

Poultry litter is widely applied as a fertilizer even though it is one of the main antibiotic sources to agricultural soils. Long-term sublethal effects (56 days) on the antioxidant system of Eisenia andrei earthworms following exposure to fluoroquinolone-contaminated poultry litter (enrofloxacin + ciprofloxacin) at 5.0, 10, and 20 g kg-1 were evaluated. The following biomarkers were assessed: superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), reduced glutathione (GSH), and a lipid peroxidation (LPO) proxy. Significant CAT and SOD increases, and a moderate positive correlation (ρ = 0.67, p < 0.05) between these enzymes was observed. Glutathione-S-transferase levels increased significantly at 10 g kg-1, while GSH exhibited a dose-dependent response at 5.0 mg kg-1 (4-106%), 10 mg kg-1 (28-330 %), and 20 mg kg-1 (45-472%). LPO levels exhibited a decreasing trend with increasing poultry litter concentrations of 8-170% (5.0 g kg-1), 7-104% (10 mg kg-1), and 3-6% (20 mg kg-1). A principal component analysis (PCA) highlighted increased SOD and CAT activities, possibly due to increased reactive oxygen species (ROS) concentrations. Biological health status assessments based on the biomarker response index indicate major alterations in the first month of exposure and becoming moderate in the second month. These findings indicate an antioxidant system attenuation trend. It is possible, however, that successive poultry litter applications may reduce the long-term recovery capacity of the evaluated biomarkers.

Triclocarban affects earthworms during long-term exposure: Behavior, cytotoxicity, oxidative stress and genotoxicity assessments.

Triclocarban (TCC) is a contaminant of emerging concern widely applied as an antimicrobial in personal care products and introduced into the terrestrial environment through the application of biosolids (i.e., treated sewage sludge) in agriculture. Displaying the potential to bioaccumulate in the food chain and a high half-life in the soil, the presence of this compound in the environment may lead to potential ecological risks. In this context, TCC toxicity assessments in Eisenia andrei earthworms were carried out through acute, avoidance and chronic tests following cytotoxicity, antioxidant system, i.e. acatalase (CAT), glutathione-S-transferase (GST), glutathione (GSH), lipid peroxidation (LPO), and DNA damage (comet assay) evaluations. An LC50 of 3.3 ± 1.6 mg cm-2 in the acute contact test and an EC50 of 1.92 ± 0.31 mg kg-1 in the avoidance test during 72 h and 48 h, respectively, were obtained. The behavioral test indicates earthworm avoidance from 15.0 mg kg-1 of TCC. During chronic soil exposure, a 44% reduction in earthworm cell viability was observed after 14 days of exposure to 10 mg kg-1 TCC, while an increase in the percentage of amoebocyte cells also ocurred. Chronic exposure to TCC led to reduced CAT and GST activities, decreased GSH levels and increased LPO in exposed organisms. DNA damage was observed after 45 days from a 1 mg kg-1 dose of TCC. Therefore, TCC exhibits toxicological potential to Eisenia andrei earthworms, mainly during long-term exposures. This study provides mechanistic earthworm information towards understanding the environmental and human health implications of TCC exposure and draws attention to correct biosolid management.

Sub-lethal effects of the pesticide imazalil on the earthworm Eisenia andrei: reproduction, cytotoxicity, and oxidative stress.

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.