A review on the ecotoxicity of macrocyclic lactones and benzimidazoles on aquatic organisms.

Despite its wide production and several applications, veterinary antiparasitics from macrocyclic lactones and benzimidazole classes have not received much scientific attention concerning their environmental risks. Thus, we aimed to provide insights into the state of the environmental research on macrocyclic lactone and benzimidazole parasiticides, emphasizing their toxicity to non-target aquatic organisms. We searched for relevant information on these pharmaceutical classes on PubMed and Web of Science. Our search yielded a total of 45 research articles. Most articles corresponded to toxicity testing (n = 29), followed by environmental fate (n = 14) and other issues (n = 2) of selected parasiticides. Macrocyclic lactones were the most studied chemical group (65% of studies). Studies were conducted mainly with invertebrate taxa (70%), with crustaceans being the most predominant group (n = 27; 51%). Daphnia magna was the most used species (n = 8; 15%). Besides, it also proved to be the most sensitive organism, yielding the lowest toxicity measure (EC50 0.25 µg/L for decreased mobility after 48 h-abamectin exposure) reported. Moreover, most studies were performed in laboratory settings, tracking a limited number of endpoints (acute mortality, immobility, and community disturbance). We posit that macrocyclic lactones and benzimidazoles warrant coordinated action to understand their environmental risks.

Electrolytic and hemogasometric parameters for female agoutis (Dasyprocta prymnolopha Wagler, 1831) raised in captivity / Parâmetros eletrolíticos e hemogasométricos para cutias fêmeas (Dasyprocta prymnolopha Wagler, 1831) criadas em cativeiro

Agoutis (Dasyprocta prymnolopha, WAGLER 1831) have been studied in captivity as a potential source of meat for rural populations in Brazil, as a way of providing low-cost protein and easing hunting pressures in local communities. However, little is known about their physiological blood markers, which are crucial for animal husbandry and effective welfare management. This study provides hemogasometric and ionic venous parameters for female agoutis raised in captivity in the drylands of Brazil. Venous blood samples were collected from six females and analyzed for dissolved gases and ions in the blood. Hemogasometric parameters, especially base excess and anion gap were generally heterogenous, while ions varied little among individuals. Moreover, we observed high chlorine values and negative base excess values, which suggest that some animals might be implementing compensatory mechanisms for ion imbalances. We provide a preliminary note on agouti venous gases and ions, while reiterating the importance of the clinical context and in-house parameter definition to maximize accuracy.(AU)

Cutias (Dasyprocta prymnolopha, WAGLER 1831) têm sido estudadas em cativeiro como uma fonte potencial de carne para populações rurais no Brasil, como uma forma de fornecer proteína de baixo custo e aliviar as pressões de caça nas comunidades locais. No entanto, pouco se sabe sobre seus marcadores sanguíneos fisiológicos os quais são cruciais para a criação animal e o manejo eficaz do bem-estar. Este estudo fornece parâmetros hemogasométricos e iônicos veno-sos para cutias fêmeas criadas em cativeiro em regiões áridas do Brasil. Amostras de sangue venoso foram coletadas de seis fêmeas e analisadas para gases dissolvidos e íons no sangue. Os parâmetros hemogasométricos, especialmente o excesso de base e o anion gap, foram heterogêneos, enquanto os íons variaram pouco entre os indivíduos. Além disso, altos valores de cloro e valores negativos de excesso de base foram observados o que sugere que alguns animais podem estar desenvol-vendo mecanismos compensatórios para desequilíbrios iônicos. Um perfil preliminar sobre gases e íons venosos de cutias foi fornecido, ao mesmo tempo, destaca-se a importância do contexto clínico e da definição interna dos parâmetros para maximizar a precisão.(AU)

Exposure to 2,4-D herbicide induces hepatotoxicity in zebrafish larvae.

2,4-Dichlorophenoxyacetic acid (2,4-D) herbicide is the main ingredient in over 1500 commercially available products such as Weedestroy® AM40 and DMA® 4 IVM. Although the liver has been identified as one of the organs that are affected by this herbicide, reports on its hepatotoxic effects available in the literature are restricted to rats. Thus, there is a gap in information on other organisms that may be vulnerable to 2,4-D exposure, such as fish. Therefore, the present work aimed to assess the hepatotoxic potential of 2,4-D in fish using zebrafish (Danio rerio) larvae as a model system. For this purpose, its acute toxicity to zebrafish embryos was assessed, as well as its sublethal effects (< LC50) on the activity of enzymes related to oxidative (GST, CAT and GPX) and metabolic (LDH) stress and liver parameters (AST, ALT and ALP) after 48 h of exposure. Morphological analyses of the liver were also assessed in zebrafish larvae. As a result, 2,4-D reduced larvae survival (LC50 15.010 mg/L in 96 h of exposure), induced malformations, altered the activity of LDH, GST and CAT enzymes and significantly increased the activity of all biomarkers for liver damage. Although no changes in the color or size of larval liver were observed, histopathological analysis revealed that treatment with 2,4-D caused severe changes in liver tissue, such as vacuolization of the cytosol, eccentric cell nucleus, loss of tissue architecture and cellular boundaries. Thus, the results showed that 2,4-D altered the enzymatic profile related to oxidative stress, and induces liver damage.

Moxidectin toxicity to zebrafish embryos: Bioaccumulation and biomarker responses.

Moxidectin is an antiparasitic drug belonging to the class of the macrocyclic lactones, subgroup mylbemicins. It is used worldwide in veterinary practice, but little is known about its potential environmental risks. Thus, we used the zebrafish embryo as a model system to study the potential effects of moxidectin on aquatic non-target organisms. The analyses were performed in two experimental sets: (1) acute toxicity and apical endpoints were characterized, with biomarker assays providing information on the activity levels of catalase (CAT), glutathione S-transferase (GST), lactate dehydrogenase (LDH), and acetylcholinesterase (AChE); and (2) internal concentration and spatial distribution of moxidectin were determined using ultraperformance liquid chromatography quadrupole-time-of-flight mass spectrometry (UPLC-QToF-MS) and matrix-assisted laser desorption/ionization-MS imaging (MALDI-MSi). The acute toxicity to zebrafish embryos (96 hpf) appeared mainly as a decrease in hatching rates (EC50 = 20.75 µg/L). It also altered the enzymatic activity of biomarker enzymes related to xenobiotic processing, anaerobic metabolism, and oxidative stress (GST, LDH, and CAT, respectively) and strongly accumulated in the embryos, as internal concentrations were 4 orders of magnitude higher than those detected in exposure solutions. MALDI-MSi revealed accumulations of the drug mainly in the head and eyes of the embryos (72 and 96 hpf). Thus, our results show that exposure to moxidectin decreases hatching success by 96 h and alters biochemical parameters in the early life stages of zebrafish while accumulating in the head and eye regions of the animals, demonstrating the need to prioritize this compound for environmental studies.

GM insect pests under the Brazilian regulatory framework: development and perspectives.

The emergence of new technologies for genetic modification has broadened the range of possible new products. The regulations of many countries that could benefit from these new products may not be prepared to assess risks and enable science-based decision-making. This is especially acute in the case of genetically modified insects with potential use in public health and agriculture. Modifications of the regulatory framework, sometimes necessary to allow a proper risk assessment of products from new technologies, are strongly influenced by political decisions derived from the balance of power and interest among stakeholders. This article discusses the genesis of the Brazilian regulatory framework, its applicability for the risk assessment of genetically modified insects and the scenarios that have shaped the two biosafety laws that established the basis for the use of modern biotechnology in the country. It is concluded that, for the adoption of the new technologies, it is important to carefully navigate the political tensions by seeking the engagement and empowerment of stakeholders supporting science-based decision-making in order to gather the necessary support for adoption of risk assessment as the basis for final decisions, allowing the use of new technologies.