Behavioral and mutagenic biomarkers in tadpoles exposed to different abamectin concentrations

Hepatotoxicity of the Pesticide Avermectin Exposure to Freshwater-Farmed Carp: Evidence from In Vivo and In Vitro Research

Avermectin (AVM) is presently one of the most extensively employed insecticides across the globe. A number of toxicity research studies of AVM have been carried out in freshwater-farmed carp; however, there are currently no toxicity studies on the liver. This investigation aims to replicate an acute liver injury model induced by AVM in carp, subsequently analyzing the adverse effects imposed on the nontarget species while delving into potential mechanisms underlying its toxicity. In this study, we found that AVM-exposed carp liver tissue showed cellular hydration degeneration and necrosis and reduced the viability of hepatocyte L8824. Second, AVM induced oxidative stress in carp, and AVM stimulation led to reactive oxygen species (ROS) accumulation and Ca2+ overload in hepatocyte L8824, suggesting that AVM exposure induces mitochondrial dysfunction in hepatocytes. AVM induced inflammation in carp liver tissue by inducing mitochondrial kinetic disruption, which triggered hepatic tissue injury. AVM induced autophagy and apoptosis in carp liver tissue and ROS mediated AVM-induced autophagy and apoptosis. The formation of autophagy attenuated the AVM-induced liver injury. In conclusion, the present study elucidated the hepatotoxicity and potential mechanisms of freshwater aquaculture carp exposed to the pesticide AVM, emphasized the importance of monitoring pesticide AVM contamination in freshwater aquaculture aquatic environments, and provided theoretical references for the targeted prevention of AVM-induced toxicity in carp.

Potential ecotoxicity of substrate-enriched zinc oxide nanoparticles to Physalaemus cuvieri tadpoles

Although the ecotoxicological effects of ZnO nanoparticles (ZnO NPs) have already been reported in different taxa, little is known about their impacts on amphibians. Thus, we aimed to evaluate the potential effects of exposure of Physalaemus cuvieri tadpoles to substrates enriched with ZnO NPs (and with its ionic counterpart, Zn+2, ZnCl2 - both at 100 mg/kg) previously used in the cultivation of Panicum maximum (Guinea grass). We showed that although exposure for 21 days did not impact the survival, growth, and development of tadpoles, we noted an increase in the frequency of erythrocyte nuclear abnormalities in the "ZnCl2" and "ZnONP" groups, which was associated with suppression of antioxidant activity in the animals (inferred by SOD and CAT activity and DPPH free radical scavenging capacity). In the tadpoles of the "ZnONP" group, we also noticed a reduction in creatinine and bilirubin levels, alpha-amylase activity, and an increase in alkaline phosphatase activity. But the treatments did not alter the activity of the enzymes lactate dehydrogenase and gamma-glutamyl-transferase and total protein and carbohydrate levels. On the other hand, we report a cholinesterase and hypotriglyceridemic effect in the "ZnCl2" and "ZnONP" groups. Zn bioaccumulation in animals, from ZnO NPs, from Zn+2 released from them, or both, has been associated with causing these changes. Finally, principal component analysis (PCA) and the values of the "Integrated Biomarker Response" index revealed that the exposure of animals to substrates enriched with ZnO NPs caused more pronounced effects than those attributed to its ionic counterpart. Therefore, our study reinforces the need to consider the environmental risks of using these nanomaterials for agricultural purposes for amphibians.

Single and mixed exposure to distinct groups of pesticides suggests endocrine disrupting properties of imidacloprid in zebrafish embryos

Due to their selective toxicity to insects, nicotinoid compounds have been widely used to control pests in crops and livestock around the world. However, despite the advantages presented, much has been discussed about their harmful effects on exposed organisms, either directly or indirectly, with regards to endocrine disruption. This study aimed to evaluate the lethal and sublethal effects of imidacloprid (IMD) and abamectin (ABA) formulations, separately and combined, on zebrafish (Danio rerio) embryos at different developmental stages. For this, Fish Embryo Toxicity (FET) tests were carried out, exposing two hours post-fertilization (hpf) zebrafish to 96 hours of treatments with five different concentrations of abamectin (0.5-11.7 mg L^-1), imidacloprid (0.0001-1.0 mg L^-1), and imidacloprid/abamectin mixtures (LC₅₀/2 - LC₅₀/1000). The results showed that IMD and ABA caused toxic effects in zebrafish embryos. Significant effects were observed regarding egg coagulation, pericardial edema, and lack of larvae hatching. However, unlike ABA, the IMD dose-response curve for mortality had a bell curve display, where medium doses caused more mortality than higher and lower doses. These data demonstrate the toxic influence of sublethal IMD and ABA concentrations on zebrafish, suggesting that these compounds should be listed for river and reservoir water-quality monitoring.

Assessment of multiple biomarkers in Lithobates catesbeianus (Anura: Ranidae) tadpoles exposed to zinc oxide nanoparticles and zinc chloride: integrating morphological and behavioral approaches to ecotoxicology

The ecotoxicological risk to vertebrates posed by zinc oxide nanoparticles (ZnO NPs) is still poorly understood, especially in animals with a biphasic life cycle, which have aquatic and terrestrial phases, such as amphibians. In the present study, we investigated whether acute exposure (7 days) to ZnO NPs and zinc chloride (ZnCl₂) at three environmentally relevant concentrations (0.1, 1.0, and 10 mg L^-1) induces changes in the morphology, chondrocranium, and behavior of the tadpoles of Lithobates catesbeianus (Anura: Ranidae). Tadpoles exposed to both forms of Zn did not undergo any morphological or behavioral changes at the lowest concentrations (0.1 and 1.0 mg L^-1). However, the animals exposed to the highest concentration (10 mg L^-1) lacked oral disc structures, were smaller in size, had a longer tail, and presented changes in the position and coiling of the intestine and malformations of the chondrocranium in comparison with the control group. This indicates that ZnO NPs and ZnCl₂ altered the development of the tadpoles, causing delays in their metamorphosis and even reducing individual fitness. The tadpoles exposed to both forms of Zn at 10 mg L^-1 also had reduced mobility, especially in the presence of conspecifics. Based on these findings, we emphasize the importance of studying morphological, skeletal, and behavioral biomarkers to evaluate the toxic effects of metal-based nanoparticles in amphibians.

Acute toxicity, biochemical and transcriptomic analysis of Procambarus clarkii exposed to avermectin

BACKGROUND

Pesticides are extensively applied globally. Pesticide residues induce calamitous effects on the environment and untargeted organisms. Public concerns for the safety of freshwater organisms and the challenges posed by aquatic contaminants remain high. In the present study, the acute toxicity of avermectins (AVMs) to the crayfish, Procambarus clarkii was evaluated. We also evaluated the potential effects of AVM on the biochemical and transcriptomic status of the hepatopancreas and gastrointestinal tract in P. clarkii.

RESULTS

The 24, 48, 72, 96 h median lethal concentrations (LC₅₀ ) of AVM on crayfish were 2.626, 1.162, 0.723, 0.566 mg L^-1 , respectively. The crayfish were then exposed to 0.65 mg L^-1 of AVM for 96 h. AVM significantly altered biochemical parameters including AChE and CAT activities in the hepatopancreas, and AChE, SOD and Na + -K + -ATPase activities in the gastrointestinal tract at several time points. Furthermore, transcriptomic analysis identified 953 and 1851 differentially-expressed genes (DEGs) in the hepatopancreas and gastrointestinal tract, respectively. KEGG enrichment showed that the gene expression profiles of the hepatopancreas and gastrointestinal tract were distinct from each other. The DEGs in the hepatopancreas were mostly enriched with stress-response pathways, while the majority of the DEGs in the gastrointestinal tract belonged to metabolism-related pathways.

CONCLUSION

We demonstrated that the AVM induced acute toxicity, oxidative stress, osmoregulation disturbance, neurotoxicity and transcriptome imbalance in crayfish. These findings unraveled the detrimental effects of AVMs exposure on crayfish. © 2022 Society of Chemical Industry.

Titanium dioxide nanoparticles as a risk factor for the health of Neotropical tadpoles: a case study of Dendropsophus minutus (Anura: Hylidae)

The production and use of titanium dioxide (TiO₂) nanoparticles are increasing worldwide. The release of this substance into the environment can induce toxic effects in aquatic invertebrates and vertebrates, although the exact nature of its impacts on Neotropical amphibians is still poorly understood. In this context, the present study evaluated the toxicity of TiO₂ nanoparticles and their counterpart-dissolved titanium dioxide (TiO₂)-in the tadpoles of Dendropsophus minutus. The biometric parameters, DNA damage, and behavioral changes were verified in tadpoles exposed to three different concentrations (0.1 mg·L^-1, 1.0 mg·L^-1, and 10 mg·L^-1) of TiO₂ nanoparticles and dissolved TiO₂ for 7 days. We verified significant DNA damage in the D. minutus tadpoles exposed to both forms of Ti, in comparison with the control group. We also identified a reduction in total size, body length, and width, and the height of the musculature of the tail of the tadpoles exposed to all concentrations of both substances in comparison with the control. In the behavioral test, the tadpoles exposed to nanoparticles and dissolved TiO₂ presented reduced mobility and a tendency to be less aggregated than normal. Here, the simultaneous use of multiple biomarkers was fundamental for the reliable assessment of the adverse effects of nanomaterials on anuran amphibians and the establishment of a systematic approach to the biomonitoring of aquatic ecosystems. The present study expands our understanding of the genotoxic, morphological, and behavioral effects of TiO₂ nanoparticles and dissolved TiO₂ on anuran amphibians, and contributes to the establishment of further research for the more systematic assessment of the environmental risk of nanomaterials.

Morphological, behavioral and genotoxic effects of glyphosate and 2,4-D mixture in tadpoles of two native species of South American amphibians

Pesticide contamination is an important factor in the global decline of amphibians. The herbicides glyphosate and 2,4-D are the most applied worldwide. These herbicides are often found in surface waters close to agricultural areas. This study aims at evaluating the chronic effects caused by glyphosate + 2,4-D mixture in Boana faber and Leptodactylus latrans tadpoles. The combined solution of the glyphosate and 2,4-D, in 5 different concentrations, was applied for 168 h. Herbicide mixtures did not affect the survival of the exposed tadpoles but growth and swimming activity were altered; besides causing several damages in the mouth and intestine. The erythrocytes showed micronuclei and other nuclear abnormalities. There is an ecological risk in the exposure of tadpoles of B. faber and L. latrans from the mixture of glyphosate + 2,4-D. Therefore, the approach used in this study provides important information on how commonly used pesticides can affect non-target organisms.

The Toxic Effects of Glyphosate, Chlorpyrifos, Abamectin, and 2,4-D on Animal Models: A Systematic Review of Brazilian Studies

Brazil is a global agricultural commodity producer and the largest consumer of pesticides. Pesticide use in Brazil comprised 549 280 tons in 2018. In the country, soybean, corn, and sugar cane are extensively produced, which are the most pesticides demanding crops. In the last years, the records of new pesticides were the highest in the historical series. They can persist in soil or water, accumulate in organisms, and contaminate workers and the general population through the air, water, or food. This review aimed to gather toxicological data obtained by animal models exposed to 4 pesticides: glyphosate, chlorpyrifos, abamectin, and 2,4-D. An additional goal was to compose an overview of how this subject has been approached, surveying which research groups are working on this field, where they are located, and relations with pesticides used in those regions. We collected the papers from the platforms PubMed, Scopus, Scielo, and Web of Science, performed in Brazil from 2014 to 2019. After two-step blind selection using the software Rayyan QCRI by different authors, 67 studies were selected to extract data. We observed that research is more concentrated in the South region, followed by the Southeast and Midwest, with 43%, 32%, and 23% of the studies, respectively. The prevalent institutions are from the states of Rio Grande do Sul, São Paulo, and Goiás. The effects on a variety of biomarkers help predict the potential risks to humans and nontarget organisms. The prevalent animal model was fish (36%). Overall, the main toxic effects evaluated were mortality, abnormalities in the blood cells, developmental abnormalities, and behavior alterations. Integr Environ Assess Manag 2021;17:507-520. © 2020 SETAC.

Toxicity and trophic transfer of polyethylene microplastics from Poecilia reticulata to Danio rerio

The potential transfer of microplastics (MPs) between vertebrates belonging to the same taxonomic group, and the impact of such a transfer on higher trophic levels remains little explored. An experimental food chain with two fish species was installed to test the hypothesis that polyethylene MPs (PE MPs) can accumulate in animals and cause behavioral, mutagenic and cytotoxic changes at upper trophic levels. Poecilia reticulata fry were exposed to MPs for 48 h and, subsequently, offered (as food) to Danio rerio adults for 10 days to simulate an upper level food chain. PE MPs quantification in fry and in different Danio rerio tissues evidenced their accumulation at the two assessed trophic levels. This finding suggested their absorption, adherence and translocation from one organism to another. The accumulation seen in D. rerio directly exposed to MPs was associated with behavioral disorders at upper trophic level. These animals presented behavior suggestive of anti-predatory response deficit when they were confronted with a potential aquatic predator (Geophagus brasiliensis). This finding was inferred through lower school cohesion, shallower school depth and shorter distance from the potential predator. In addition, animals exposed to MPs recorded higher nuclear abnormality rates and changes in the size and shape of erythrocytes and in their nuclei; this outcome has suggested mutagenic and cytotoxic effects, respectively. Based on the current results, MPs are transferred through a food chain that only involves two vertebrates. MPs enter the vertebrates' organs, change their behavior and induce mutagenic and cytotoxic processes in animals, which can cause significant ecological consequences in freshwater ecosystems.

Can short exposure to polyethylene microplastics change tadpoles' behavior? A study conducted with neotropical tadpole species belonging to order anura (Physalaemus cuvieri)

The scientific knowledge about toxicological impacts of polyethylene microplastics (PE MPs) on different organisms has significantly improved in recent years. However, the effects of these pollutants on animal species such as amphibians remain poorly known. Thus, the aim of the current study is to investigate whether the short exposure (7 days) of Physalaemus cuvieri tadpoles to PE MPs (60 mg/L) can change their behavior. Collected data have shown that PE MP accumulation in tadpoles was associated with different behavioral changes observed in them; this outcome has confirmed the behavioral toxicity of these micropollutants in the investigated species. Tadpoles subjected to PE MPs presented locomotion issues, anxiogenic effect symptoms, as well as anti-predatory defensive response deficit when they were exposed to predators (Cyprinus carpio). Data analysis enabled inferring to what extent these pollutants can affect individuals, and their natural predators living in contaminated areas. Based on the biological viewpoint, these changes can affect their defensive response to predators, as well as their social behavior. To the best of our knowledge, the present study was pioneer in reporting PE MPs-induced behavioral toxicity in representatives of amphibian groups.

Abamectin induces cytotoxicity via the ROS, JNK, and ATM/ATR pathways

Abamectin has been widely used in agriculture and animal husbandry. It has been shown that abamectin exposure could induce multiple toxic effects on non-target organisms, but the underlying mechanism is still largely unknown. In the current study, the mechanism of abamectin-induced cytotoxicity was investigated in mouse embryonic fibroblast cells. Abamectin treatment could cause oxidative stress in cells (beginning at 0.4 μg/ml, 0.5 μM) and the ROS overproduction was mainly induced by the impacts of abamectin on the activities of CAT (beginning at 4.4 μg/mL, 5 μM), SOD (beginning at 8.7 μg/mL, 10 μM), GPx (beginning at 4.4 μg/mL, 5 μM), and contents of GSH (beginning at 4.4 μg/mL, 5 μM), which are important components of the ROS elimination pathway in mammal cells. Abamectin could impair DNA integrity (as demonstrated by increased 8-OHdG/dG ratio) in cells, even at environmental level (0.4 μg/mL, NOAEL), and abamectin-induced oxidative stress was one of the main reasons for the DNA damage that occurred in cells. Moreover, pretreatment with the inhibitor of JNK and ATM/ATR signaling pathway could partially rescue the decreased cell viability, indicating that oxidative stress and DNA damage might be involved in abamectin-induced cytotoxicity. These findings could provide new insights into the mechanism of abamectin-induced cytotoxicity and should be useful for a more comprehensive assessment of the adverse effects of abamectin.

Micronucleus test in tadpole erythrocytes: Trends in studies and new paths

The micronucleus test has been applied for more than three decades in tadpoles, generating an early warning of environmental quality. In this study, we reviewed 48 articles on the micronucleus test in tadpoles, published between 1987 and 2018. The findings reveal that pesticides have been the main topic discussed in the induction of micronucleus and other nuclear abnormalities in anuran larvae to the detriment of the widespread use of compounds used in agriculture. In addition to pesticides, a number of other xenobiotic agents have been targeted for genotoxic damage, such as heavy metals, radiation and wastewater. An appeal is reported to environmental contaminants, which when released naturally into the environment or because of human activities may contaminate aquatic habitats, threatening populations of tadpoles that depend on these environments for their survival. Larvae can bioaccumulate these contaminants that cause progressive impacts, ranging from DNA damage to metamorphosis delays, as well as malformations. We found that Argentina is the main driving force for the application of this test in anuran larvae along with Brazil. Different erythrocyte malformations have been reported for the erythrocyte nuclear abnormalities test, binucleated cells, nuclear buds, notched, lobed, reniform, nuclear bebbled, anucleated, picnotic and apoptotic cells are the most cited. In summary, the presence of chemical or physical agents, along with other disturbances of the habitat, can have a significant impact on the life history of the species, contributing to the decline of anuran populations.

How much are microplastics harmful to the health of amphibians? A study with pristine polyethylene microplastics and Physalaemus cuvieri

Microplastics (MPs) are critical emerging pollutants found in the environment worldwide; however, its toxicity in aquatic in amphibians, is poorly known. Thus, the aim of the present study is to assess the toxicological potential of polyethylene microplastics (PE MPs) in Physalaemus cuvieri tadpoles. According to the results, tadpoles' exposure to MP PE at concentration 60 mg/L for 7 days led to mutagenic effects, which were evidenced by the increased number of abnormalities observed in nuclear erythrocytes. The small size of erythrocytes and their nuclei area, perimeter, width, length, and radius, as well as the lower nucleus/cytoplasm ratio observed in tadpoles exposed to PE MPs confirmed its cytotoxicity. External morphological changes observed in the animal models included reduced ratio between total length and mouth-cloaca distance, caudal length, ocular area, mouth area, among others. PE MPs increased the number of melanophores in the skin and pigmentation rate in the assessed areas. Finally, PE MPs were found in gills, gastrointestinal tract, liver, muscle tissues of the tail and in the blood, a fact that confirmed MP accumulation by tadpoles. Therefore, the present study pioneering evidenced how MPs can affect the health of amphibians.

First report on the mutagenicity and cytotoxicity of Zno nanoparticles in reptiles

Understanding how human activities affect animal biodiversity is essential to investigations about the biological effects of several pollutants and contaminants dispersed in the environment. This is the case of zinc oxide nanoparticles (ZnO NPs), which are emerging pollutants whose effect on reptiles' health is completely unknown. Thus, the objective of the present study is to evaluate the possible damages induced by these NPs in Podocnemis expansa juveniles (Amazon turtle) by using morphological changes of circulating erythrocytes as nuclear toxicity biomarker. The animals were exposed to the intramuscular administration of 440 μg/kg and 440,000 μg/kg of ZnO NPs, for 10 consecutive days. The micronuclei assay and other nuclear abnormalities were performed at the end of the experiment, as well as different morphometric measurements applied to the erythrocytes. Based on the current data, ZnO NPs induced nuclear abnormalities such as micronuclei and binucleation, which are associated with carcinogenic processes and with flaws in the mitotic machinery. The low "nuclear area: erythrocyte area" ratio and larger cytoplasmic area observed for animals exposed to NPs evidenced erythrocytic change induction likely related to negative energy balance/metabolism interferences and/or to oxygen transportation efficiency by erythrocytes. This is the first report on the mutagenic and cytotoxic effect induced by NPs on representatives of a group of reptiles. This outcome suggests that further investigations must focus on better understanding the (eco)toxicological potential of ZnO NPs.

Behavioral toxicity of tannery effluent in zebrafish (Danio rerio) used as model system

The ecotoxicity of untreated tannery effluent (UTE) in several animal models has been reported; however, its effects on fish behavior, and neurotoxicity, remain unknown. Thus, the hypothesis that the chronic exposure to UTE can induce behavioral changes in adult zebrafish (Danio rerio) representatives, even when it is highly diluted in water, was tested. Animals exposed to 0.1% and 0.3% UTE for 30 days showed behavioral changes in visual social preference tests through their co-specific and antipredator defensive responses, which had indicated neurotoxic actions. Zebrafish exposed to UTE appeared to have not co-specific preference when it is paired with Poecilia sphrenops. In addition, only animals in the control group showed aversive behavior in the presence of the herein used predatory stimulus (Oreochromis niloticus). However, Cr, Na and Mg bioaccumulation was higher in zebrafish exposed to 0.1% and 0.3% UTE, although anxiogenic and anxiolytic effects were not observed in the models exposed to UTE in the novel tank diving or aggressiveness-increase-in-the-mirror tests. This outcome allowed associating the exposure to the pollutant and bioaccumulation with the observed behavioral changes. The present study is pioneer in scientifically evidencing the sublethal impact caused by chronic exposure to UTE in experimental environment simulating realistic aquatic pollution conditions. Accordingly, results in the current research should motivate further investigations to broaden the knowledge about the real magnitude of UTE biological impacts on the aquatic biota.

Ingestion of tannery effluent as a risk factor to the health of birds: A toxicological study using Coturnix coturnix japonica as a model system

Tannery industries generate large amounts of tannery effluents (TE), which have been considered highly toxic to various groups of animals. However, the identification and characterization of the impact of this mix of pollutants on birds is still highly incipient. So, our goal was to evaluate the possible biological changes of Coturnix coturnix japonica, exposed for 45 days, to different dilutions of TE (1.4%, 3.1% and 6.5%), using behavioural biomarkers, mutagenics and egg production. When submitted to the behavioural tests, quails that ingested TE presented behaviour compatible with an anxiolytic effect in the open field test; absence of emotional reactivity in the object recognition test; reduced rates of predation of Tenebrio molitor larvae (potential prey); as well as an anti-predatory defensive response deficit when confronted, especially with Felis catus males (potential predator). In addition, we observed increased biomass of the liver, increased feed conversion index and lower feed efficiency index; mutagenic effect of TE (inferred by the increase of nuclear erythrocyte abnormalities); reduced productive performance and egg quality, in addition to different staining patterns of the eggs produced by quails from the control group. Therefore, our study confirms the toxicity of TE in C. coturnix japonica, even in small dilutions. While behavioural changes demonstrate the neurotoxic potential of the pollutant, the other alterations suggest that the mechanisms of action of its chemical constituents are not selective, that is, they act systemically, acting synergistic, antagonistic or additively, causing harmful effects in animals.

Abamectin induces apoptosis and autophagy by inhibiting reactive oxygen species-mediated PI3K/AKT signaling in MGC803 cells

Abamectin (ABA) is one of the most widely used compounds in agriculture and veterinary medicine. However, the cytotoxicity of ABA in human gastric cells is utterly unknown. In this study, ABA suppressed the proliferation of MGC803 cells by arresting the cell cycle at the G0/G1-phase. Moreover, ABA induced mitochondrial-mediated apoptosis by inducing the loss of mitochondrial membrane potential, upregulation of Bax/Bcl-2, and activation of caspase-3. ABA significantly improved the LC3-II/LC3-I ratio and reduced P62 protein expression in a dose-dependent manner. Through detection of the reactive oxygen species (ROS) levels, we found ABA induced the accumulation of intracellular ROS and then reduced PI3K/AKT signaling activation related to MGC803 cell apoptosis and autophagy. Our results indicate that ABA exerts cytotoxic effects on human MGC803 cells through apoptosis and autophagy by inhibiting ROS-mediated PI3K/AKT signaling. Furthermore, ABA may be a potential risk to human gastric health.

Sub-lethal effects induced by a mixture of different pharmaceutical drugs in predicted environmentally relevant concentrations on Lithobates catesbeianus (Shaw, 1802) (Anura, ranidae) tadpoles

The increasing consumption of medications by humans has negative effects such as the increased disposal of these compounds in the environment. Little is known about how the disposal of a "drug mix" (DM) in aquatic ecosystems can affect their biota. Thus, we evaluated whether the exposure of Lithobates casteibeianus tadpoles to a DM composed of different medication classes (antibiotic, anti-inflammatory, antidepressant, anxiolytic, analgesic, and antacid drugs)-at environmentally relevant concentrations-may change their oral morphology, trigger behavioral disorders, and have mutagenic effects on erythrocyte cells. Based on our data, animals exposed to the DM showed changes in mandibular sheath pigmentation, dentition, and swimming activity, as well as atypical behavior in the social aggregation test [with co-specific and interspecific (Physalaemus cuvieri) individuals] and antipredatory defensive response deficit (chemical stimulus from Odonata larvae), after 15 exposure days. The mutagenic analysis revealed higher frequency of nuclear abnormalities in the erythrocytes of tadpoles exposed to the DM (e.g., multilobulated, blebbed, kidney-shaped, notched nucleus, binuclear, and micronucleated erythrocytes). Given the chemical complexity of the DM, we assumed that several organic functions may have been affected, either by the isolated, synergistic, antagonistic, or additive action of DM compounds. Finally, our study confirms the toxicological potential of DM in L. catesbeianus tadpoles, with emphasis to impacts that can affect the fitness of individuals and their natural populations. Thus, we suggest that more attention should be given to the disposal of medications in the environment and reinforce the need of improving water and sewage treatment systems.