Environmental Hormone Effects and Bioaccumulation of Propiconazole and Difenoconazole in Procypris merus

Bioavailability assessment of propiconazole to Limnobium laevigatum and zebrafish (Danio rerio) in aquatic microcosms

Residues of the triazole fungicide propiconazole (PCZ) in the environment can easily enter aquatic ecosystems through various pathways and accumulate in sediments, thus threatening ecosystem stability. The method of using passive sampling techniques to measure the freely dissolved concentration (Cfree) of pollutants in aquatic environments for assessing their bioavailability has been widely utilized in environmental risk assessments. This study employs oleic acid-embedded cellulose acetate membrane (OECAM) as a tool to determine the Cfree of PCZ in water. By establishing sediment spiking concentrations of 0.1 and 0.5 mg/kg in an aquatic microcosm, the distribution and bioaccumulation of PCZ in zebrafish (Danio rerio) and the aquatic plant Limnobium laevigatum (L. laevigatum) were examined over a 7-day period. During the experimental period, the concentrations of PCZ in the water for the 0.1 mg/kg and 0.5 mg/kg treatment groups remained approximately 0.9 μg/L and 10.0 μg/L, respectively. After 7 days, the PCZ content in the sediments decreased by 22.74% and 14.94%, respectively. In both zebrafish and L. laevigatum, the concentration of PCZ initially increased and then gradually stabilized, with both species exhibiting moderate accumulation ability for PCZ. The bioconcentration factor (BCF) for zebrafish in the 0.1 mg/kg and 0.5 mg/kg treatment groups ranged from 9.25 to 13.96 and 7.84-16.05, respectively, while those for L. laevigatum ranged from 28.17 to 31.40 and 23.01-36.11, respectively. By the end of the 7-day experiment, the total PCZ content in both treatment groups decreased by an average of 17.51%. Among them, L. laevigatum contributed significantly, highlighting its potential in accelerating the removal of PCZ from aquatic ecosystems.

Toxic effects of eight azole fungicides on the growth, photosynthetic activity, and oxidative stress of Raphidocelis subcapitata

This study investigates the 96 hr toxicity and physiological effects of eight azole fungicides on Raphidocelis subcapitata (R. subcapitata). The findings revealed significant differences in toxicity levels among these fungicides, with the hierarchy of toxicity as follows: difenoconazole ≈ tetraconazole ≈ fuberidazole > metconazole > terrazole ≈ triflumizole > flutriafol > hymexazol. Increased concentrations of azole fungicides corresponded with decreased cellular activity and inhibited algal growth, highlighting the concentration-dependent nature of toxicity. The toxicological mechanisms involved include reduced levels of chlorophyll (Chla, Chlb) and carotenoids, disrupting the photosynthetic process. Additionally, exposure to these fungicides resulted in decreased total protein levels, increased reactive oxygen species and malondialdehyde, and elevated activity of antioxidant enzymes such as superoxide dismutase and catalase. Consequently, there was a significant rise in apoptosis rates among algal cells. These findings provide important insights for assessing the ecological impact of azole fungicides on aquatic ecosystems and aquatic life.

Effects of Difenoconazole on Tubifex tubifex: Antioxidant Activity, Insights from GUTS Predictions, and Multi-Biomarker Analysis

The increasing demand for agricultural products has led to a rise in pesticide use, resulting in the pollution of aquatic habitats and raising significant health concerns for both aquatic life and humans. Difenoconazole, a triazole fungicide, is becoming increasingly popular in agriculture, yet its effects on non-target organisms, such as annelids, are not well understood. This study aimed to investigate the toxicological effects of difenoconazole and assess its potential impact on toxicity biomarkers, using Tubifex tubifex as a model organism, to better understand the ecotoxicity of difenoconazole on freshwater annelids. The 96-h LC50 value of difenoconazole was determined to be 2.68 mg/L. Sublethal concentrations (10% and 20% of the 96-h LC50 value; 0.268 and 0.536 mg/L, respectively) caused significant changes in the activities of oxidative stress enzymes. A concentration- and time-dependent decrease in the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione transferase (GST) was observed compared to control organisms. Additionally, malondialdehyde (MDA) concentrations increased throughout the exposure period. An Integrated Biomarker Response (IBR) assessment was used to characterize and illustrate the impact of difenoconazole on T. tubifex. In conclusion, exposure to this fungicide appears to reduce the survival rate of T. tubifex at acute levels and disrupt its normal behavioral patterns. Moreover, it alters oxidative stress enzyme levels during sublethal exposure. Long-term exposure to the fungicide could potentially have population-level consequences, including a reduction in the number of individuals within a population.

Recent advances in the toxicological effects of difenoconazole: A focus on toxic mechanisms in fish and mammals

The toxicological study of pesticides at sub-lethal and environment-relevant concentrations has become increasingly crucial for human and environmental health. Toxic mechanisms of agrochemicals contribute to discovering green pesticides, assessing the hazards of pesticides comprehensively, and supporting legitimate regulatory decisions. However, the toxicological effects of difenoconazole are not yet fully understood despite being frequently detected in fruits, vegetables, waters, and soils and posing hazards to humans and the environment. This lack of knowledge could lead to flawed risk assessment and administrative oversight. Thus, the review aimed to provide some investigation perspectives for clarifying the toxicological effects of difenoconazole by synthesizing the toxic data of difenoconazole on various organisms, such as bees, Daphnia magna, fish, earthworms, mammals, and plants and summarizing the toxicological mechanisms of difenoconazole, especially in fish and mammals from peer-reviewed publications. Evidence revealed that difenoconazole caused multiple toxicological effects, including developmental toxicity, reproductive toxicity, endocrine disruption effects, neurotoxicity, and transgenerational toxicity. The toxic mechanisms involved in metabolic disturbance, oxidative stress, inflammation, apoptosis, and autophagy by activating reactive oxygen species-mediated signaling pathways and mitochondrial apoptosis routes, disturbing amino acids, lipid, and nucleotide metabolism, and regulating gene transcription and expression in mammals and fish. Based on the review, further studies better focus on the toxic differences of difenoconazole stereoisomers, the toxicological effects of transformation products of difenoconazole, and the mechanism of action of difenoconazole on sex-specific endocrine disruption effects, intestinal damage, and gut dysbacteriosis for its hazard assessment and management synthetically.

Protective effect of feed additive ferulic acid on respiratory depression and oxidation imbalance of carp induced by pesticide difenoconazole via ROS/NF-κB/NLRP3 axis

Difenoconazole (DFZ), classified as a "low-toxicity pesticide," has seen widespread application in recent years. Nevertheless, the non-target toxicity of the substance, particularly towards aquatic creatures, has generated considerable apprehension. The anti-inflammatory and antioxidant effects of Ferulic Acid (FA) have attracted considerable study in this particular setting. This study established a chronic exposure model to DFZ and investigated the protective effects of FA on chronic respiratory inhibition leading to gill damage in freshwater carp. Histological analyses via HE staining indicated that FA effectively alleviated gill tissue damage induced by chronic DFZ exposure. The qRT-PCR results showed that the addition of FA reduced the expression of IL-1β, IL-6 and TNF-α while boosting the expression of IL-10 and TGF-β1. Biochemical analyses and DHE staining revealed that FA reduced MDA levels and increased CAT and GSH activities, along with T-AOC, decreased ROS accumulation in response to chronic DFZ exposure. The results obtained from Western blotting analysis demonstrated that the addition of FA effectively suppressed the activation of the NF-κB signalling pathway and the NLRP3 inflammasome pathway in the gills subjected to prolonged exposure to DFZ. In summary, FA ameliorated gill tissue inflammation and blocked ROS accumulation in carp exposed to chronic DFZ, mitigating tissue inflammation and restoring redox homeostasis through the NF-κB-NLRP3 signaling pathway. Hence, the application of FA has been found to be efficacious for improving respiratory inhibition and mitigating gill tissue inflammation and oxidative stress resulting from DFZ pollution in aquatic habitats.

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.

Antioxidant enzyme activity and pathophysiological consequences in the sludge worm Tubifex tubifex under acute and sub-lethal exposures to the fungicide Tilt ®

This study aimed to evaluate the effects of propiconazole on the tubificid segmented worm, Tubifex tubifex. The animals were exposed to various concentrations of propiconazole for 96 h to assess the acute effect of this fungicide and for subacute level animals were exposed for 14 days with 10% and 20% of the 96 h LC50 value (0.211 and 0.422 mg/l, respectively). The 96 h LC50 value was determined to be 2.110 mg/l, and sublethal propiconazole concentrations caused significant changes in the oxidative stress enzymes. When compared to control organisms, superoxide dismutase (SOD) and catalase (CAT) activity first decreases and then significantly increases on days 7 and 14. However, GST activity decreases and MDA concentration rises in a concentration- and time-dependent manner throughout the exposure period. In addition, the impacts of propiconazole on Tubifex tubifex were characterized and depicted using a correlation matrix and an integrated biomarker response (IBR) assessment. These findings suggest that exposure to this fungicide distorts the survivability and behavioral response in Tubifex tubifex at the acute level. In addition, it modulates changes in oxidative stress enzymes at the sublethal level. Furthermore, the species sensitivity distribution curve indicates that this tubificid worm has a high risk of survival in the presence of the fungicide propiconazole in aquatic ecosystems.

Difenoconazole Exposure Induces Retinoic Acid Signaling Dysregulation and Testicular Injury in Mice Testes

Difenoconazole (DFZ) is a broad-spectrum triazole fungicide that is widely utilized in agriculture. Although DFZ has been demonstrated to induce reproductive toxicity in aquatic species, its toxic effects on the mammalian reproductive system have yet to be fully elucidated. In vivo, male mice were administered 0, 20 or 40 mg/kg/d of DFZ via oral gavage for 35 days. Consequently, DFZ significantly decreased testicular organ coefficient, sperm count and testosterone levels, augmented sperm malformation rates, and elicited histopathological alterations in testes. TUNEL assay showed increased apoptosis in testis. Western blotting results suggested abnormally high expression of the sperm meiosis-associated proteins STRA8 and SCP3. The concentrations of retinoic acid (RA), retinaldehyde (RE), and retinol (ROL) were increased in the testicular tissues of DFZ-treated groups. The mRNA expression level of genes implicated in RA synthesis significantly increased while genes involved in RA catabolism significantly decreased. In vitro, DFZ reduced cell viability and increased RA, RE, and ROL levels in GC-2 cells. Transcriptome analysis revealed a significant enrichment of numerous terms associated with the RA pathway and apoptosis. The qPCR experiment verified the transcriptome results. In conclusion, our results indicate that DFZ exposure can disrupt RA signaling pathway homeostasis, and induce testicular injury in mice testes.

Crosstalk of oxidative stress, inflammation, apoptosis, and autophagy under reactive oxygen stress involved in difenoconazole-induced kidney damage in carp

Difenoconazole is a commonly used triazole fungicide in agricultural production. Because of its slow degradation and easy accumulation in the environment, it seriously endangers both animal health and the ecological environment. Therefore, it is hoped that the effects on carp kidneys can be studied by simulating difenoconazole residues in the environment. The experiment was designed with two doses (0.488 mg/L, 1.953 mg/L) as exposure concentrations of difenoconazole for 4 d. Histopathological results showed that difenoconazole could cause severe damage to the kidney structure and extensive inflammatory cell infiltration in carp. Elevated levels of Creatinine, and BUN suggested the development of kidney damage. The DHE fluorescence probe's result suggested that difenoconazole might cause reactive oxygen species (ROS) to accumulate in the kidney of carp. Difenoconazole was found to increase MDA levels while decreasing the activities of CAT, SOD, and GSH-PX, according to biochemical indicators. In addition, difenoconazole could up-regulate the transcription levels of inflammatory factors tnf-α, il-6, il-1β, and inos. At the same time, it inhibited the transcription level of il-10 and tgf-β1. The TUNEL test clearly showed that difenoconazole induced apoptosis in the kidney and vastly raised the transcript levels of apoptosis-related genes p53, caspase9, caspase3, and bax while inhibiting the expression of Bcl-2, fas, capsase8. Additionally, TEM imaging showed that clearly autophagic lysosomes and autophagosomes were formed. Elevated levels of LC3II protein expression, increased transcript levels of the autophagy-related gene atg5 as well as decreased transcript levels of p62 represented the generation of autophagy. In conclusion, the study illustrated that oxidative stress, inflammation, apoptosis, and autophagy all played roles in difenoconazole-induced kidney injury in carp, which was closely linked to ROS production. This work provides a valuable reference for studying the toxicity of difenoconazole to aquatic organisms.