"Fishcide" effect of the fungicide difenoconazole in freshwater fish (Labeo rohita): A multi-endpoint approach

Impact of continuous Triazophos exposure on Labeo rohita: Physiological, biochemical, and histological alterations and IBRv2 index assessment

Pesticides are commonly used in agriculture and aquaculture. Triazophos, an organophosphate-based pesticide, is widely used in agriculture to control many insect pests. Due to its high photochemical stability and mode of action, Triazophos could persist in the aquatic ecosystem and cause toxic effects on non-target organisms. We have studied the potential toxic effects of Triazophos on L. rohita. Primarily, we determined the median lethal concentration (LC50) of Triazophos for 24 and 96 h. Next, we studied acute (96 h, LC50-96 h) toxicity. Then, we studied chronic (35 days, 1/10th LC50-24 h Treatment I: 0.609 mg/L, 1/5th LC50-96 h Treatment II: 1.044 mg/L) toxicity. We analyzed blood biomarkers such as hematology (Hb, Hct, RBC, WBC, MCV, MCH and MCHC), prolactin, cortisol, glucose and protein levels. Concurrently, we analyzed tissue biomarkers such as glycogen, GOT, GPT, LDH and histopathology. IBRv2 index assessment method was also to evaluate the Triazophos toxicity. Studied hematological, hormonal, biochemical and enzymological biomarkers were affected in Triazophos treated groups when compare to the control group. The changes in these biomarkers were statistically significant at the 0.05 alpha level. Triazophos exposed fish shown a severe degenerated primary and secondary lamellae, lamellar fusion, hypertrophy and telangiectasia in the gills. In the hepatic tissue, it caused moderate necrosis, blood congestion, distended sinusoids with minor vacuolation, prominent pyknotic nuclei, hypertrophy, cloudy swelling of cells, lipid accumulation and fibrotic lesions. In the renal tissue, Triazophos caused thickening of Bowman's capsule, hyaline droplets degeneration, irregular renal corpuscle, congestion, cellular swelling, degeneration of tubular epithelium, necrosis, shrunken glomerulus, vacuolated glomerulus, hypertrophy, exudate and edema. IBRv2 analysis suggested that tissue biomarkers are highly sensitive to Triazophos toxicity and prolonged exposure could cause serious health effects like acute toxicity in fish. Triazophos could cause multiorgan toxicity at studied concentrations.

Characterization of workers or population percentage affected by low-back pain (LPB), sciatica and herniated disc due to whole-body vibrations (WBV)

Whole-body vibrations have several harmful effects on the population's health. The most suitable way to characterize the vibrations is to use the daily vibration exposure A (8) and Vibration Dose Value as specified in Directive 2002/44/EC. Therefore, based on the existing literature, we propose Probit equations that allow us to relate the population percentage affected by the vibration effects (low-back pain, sciatica, and herniated disc) with the A (8) and the Vibration Dose Value. It is worth noting that there is a good correlation between the experimental data and the expressions obtained, especially for low-back pain and herniated discs. Once the expressions have been validated, we analyze the limit values given in the aforementioned legislation, showing that the percentage of the affected population is significant for them. Therefore, this study also proposes new limits based on their own definitions, which are more in line with the results shown in the bibliography.

Tracing the dissipation of difenoconazole, its metabolites and co-formulants in tomato: A comprehensive analysis by chromatography coupled to high resolution mass spectrometry in laboratory and greenhouse trials

The study evaluated Ceremonia 25 EC®, a plant protection product (PPP) containing difenoconazole, in tomato crops, to identify potential risks associated with PPPs, and in addition to this compound, known metabolites from difenoconazole degradation and co-formulants present in the PPP were monitored. An ultra high performance liquid chromatography coupled to quadrupole-Orbitrap mass analyser (UHPLC-Q-Orbitrap-MS) method was validated with a working range of 2 μg/kg (limit of quantification, LOQ) to 200 μg/kg. Difenoconazole degradation followed a biphasic double first-order in parallel (DFOP) kinetic model in laboratory and greenhouse trials, with high accuracy (R2 > 0.9965). CGA-205374, difenoconazole-alcohol, and hydroxy-difenoconazole metabolites were tentatively identified and semi-quantified in laboratory trials by UHPLC-Q-Orbitrap-MS from day 2 to day 30. No metabolites were found in greenhouse trials. Additionally, 13 volatile co-formulants were tentatively identified by gas chromatography (GC) coupled to Q-Orbitrap-MS, detectable up to the 7th day after PPP application. This study provides a comprehensive understanding of difenoconazole dissipation in tomatoes, identification of metabolites, and detection of co-formulants associated with the applied PPP.

Aquatic and sediment ecotoxicity data of difenoconazole and its potential environmental risks in ponds bordering rice paddies

Difenoconazole has a widespread agricultural use to control fungal diseases in crops, including rice. In edge-of-field surface waters the residues of this lipophilic fungicide may be toxic to both pelagic and benthic organisms. To allow an effect assessment we mined the regulatory and open literature for aquatic toxicity data. Since published sediment toxicity data were scarce we conducted 28 d sediment-spiked toxicity test with 8 species of benthic macroinvertebrates. Ecotoxicological threshold levels for effects were assessed by applying the species sensitivity distribution approach. Based on short-term L(E)C50's for aquatic organisms from water-only tests an acute Hazardous Concentration to 5% of the species (HC5) of 100 µg difenoconazole/L was obtained, while the HC5 based on chronic NOEC values was a factor of 104 lower (0.96 µg difenoconazole/L). For benthic macroinvertebrates the chronic HC5, based on 28d-L(E)C10 values, was 0.82 mg difenoconazole/kg dry weight sediment. To allow a risk assessment for water- and sediment-dwelling organisms, exposure concentrations were predicted for the water and sediment compartment of an edge-of-field pond bordering rice paddies treated with difenoconazole using the Chinese Top-Rice modelling approach, the Chinese Nanchang exposure scenario and the Equilibrium Partitioning theory. It appeared that in the vast majority of the 20 climate years simulated, potential risks to aquatic and sediment organisms cannot be excluded. Although the HC5 values based on laboratory toxicity data provide one line of evidence only, our evaluation suggests population- and community-level effects on these organisms due to chronic risks in particular.

Quercetin alleviates the toxicity of difenoconazole to the respiratory system of carp by reducing ROS accumulation and maintaining mitochondrial dynamic balance

Difenoconazole (DFZ) is a fungicidal pesticide extensively employed for the management of fungal diseases in fruits, vegetables, and cereal crops. However, its potential environmental impact cannot be ignored, as DFZ accumulation is able to lead to aquatic environment pollution and harm to non-target organisms. Quercetin (QUE), a flavonoid abundant in fruits and vegetables, possesses antioxidant and anti-inflammatory properties. In this article, carp were exposed to 400 mg/kg QUE and/or 0.3906 mg/L DFZ for 30 d to investigate the effect of QUE on DFZ-induced respiratory toxicity in carp. Research shows that DFZ exposure increases reactive oxygen species (ROS) production in the carp's respiratory system, leading to oxidative stress, inflammation, and damage to gill tissue and tight junction proteins. Further research demonstrates that DFZ induces mitochondrial dynamic imbalance and gill cell apoptosis. Notably, QUE treatment significantly reduces ROS levels, alleviates oxidative stress and inflammation, and mitigates mitochondrial dynamics imbalance and mitochondrial apoptosis. This study emphasizes the profound mechanism of DFZ toxicity to the respiratory system of common carp and the beneficial role of QUE in mitigating DFZ toxicity. These findings contribute to a better understanding of pesticide risk assessment in aquatic systems and provide new insights into strategies to reduce their toxicity.

Immunotoxicological, histopathological, and ultrastructural effects of waterborne pyrogallol exposure on African catfish (Clariasgariepinus)

Pyrogallol is a naturally occurring polyphenol derived from natural plants, such as Acer rubrum and Eucalyptus sp. The current study was designed to evaluated pyrogallol-mediated toxicity at sublethal levels (1, 5, and 10 mg/L), derived from 96 h-LC50 values previously determined for African catfish (Clarias gariepinus). Immunotoxicological indices, histological, histochemical, and ultrastructural alterations in C. gariepinus were evaluated following a 15-day pyrogallol exposure. Pyrogallol decreased immune parameters [lysozyme activity (LYZ), immunoglobulin M (IgM), and phagocytic activity] and increased pro-inflammatory cytokines, interleukin-1 beta (IL-1β), interleukin-6 (IL-6) in the serum of C. gariepinus. In addition, histopathology analysis demonstrated that exposure to pyrogallol induced injury in the liver and spleen of fish. Cellular changes in the liver include hepatocyte hydropic degeneration, melanomacrophage, vacuolated hepatocytes, congested blood, severe structural deformation, and hemorrhage. In the spleen, ellipsoid structures, melanomacrophage centers, and infiltration of inflammatory cells were evident. Together, a high frequency of histopathological lesions was scored in both the liver and spleen of C. gariepinus, which showed a dose-dependent relationship between pyrogallol exposure and histopathological indices. Our data suggest that dysfunction in the immune system may be mediated by pyrogallol-induced changes in cytokines.

Effects of microplastics, pesticides and nano-materials on fish health, oxidative stress and antioxidant defense mechanism

Microplastics and pesticides are emerging contaminants in the marine biota, which cause many harmful effects on aquatic organisms, especially on fish. Fish is a staple and affordable food source, rich in animal protein, along with various vitamins, essential amino acids, and minerals. Exposure of fish to microplastics, pesticides, and various nanoparticles generates ROS and induces oxidative stress, inflammation, immunotoxicity, genotoxicity, and DNA damage and alters gut microbiota, thus reducing the growth and quality of fish. Changes in fish behavioral patterns, swimming, and feeding habits were also observed under exposures to the above contaminants. These contaminants also affect the Nrf-2, JNK, ERK, NF-κB, and MAPK signaling pathways. And Nrf2-KEAP1 signalling modulates redox status marinating enzymes in fish. Effects of pesticides, microplastics, and nanoparticles found to modulate many antioxidant enzymes, including superoxide dismutase, catalase, and glutathione system. So, to protect fish health from stress, the contribution of nano-technology or nano-formulations was researched. A decrease in fish nutritional quality and population significantly impacts on the human diet, influencing traditions and economics worldwide. On the other hand, traces of microplastics and pesticides in the habitat water can enter humans by consuming contaminated fish which may result in serious health hazards. This review summarizes the oxidative stress caused due to microplastics, pesticides and nano-particle contamination or exposure in fish habitat water and their impact on human health. As a rescue mechanism, the use of nano-technology in the management of fish health and disease was discussed.

Mechanisms regarding respiratory toxicity triggered by accumulation of ROS in carp exposed to difenoconazole

Difenoconazole is a widely used but difficult-to-degrade fungicide that can directly affect aquatic ecosystems. Here, two doses (0.488 mg/L, 1.953 mg/L) of difenoconazole were used to study the toxicity to the respiratory system of carp at an exposure time of 96 h. The results showed that difenoconazole exposure resulted in severe structural damage to carp gill tissue with extensive inflammatory cell infiltration. Mechanistically, difenoconazole exposure led to excessive accumulation of ROS in carp gill tissue, which induced an inflammatory response in the gill tissue. Meanwhile, the activities of SOD and CAT were reduced and the NRF2 signaling pathway was activated to regulate the imbalance between oxidation and antioxidation. In addition, difenoconazole exposure further activated the mitochondrial pathway of apoptosis by upregulating cytochrome C, BAX, cleaved-caspase 9, and downregulating Bcl-2. More interestingly, exposure to difenoconazole increased autophagosomes, but lysosomal dysfunction prevented the late stages of autophagy from proceeding smoothly, resulting in a protective autophagic response that is not properly initiated. In summary, difenoconazole exposure caused respiratory toxicity including inflammation response, oxidative stress, apoptosis, and autophagy in carp through the accumulation of ROS. The present study expanded our understanding of the toxic effects of difenoconazole on organisms and its possible threat to the aquatic environment.