Biotransformation, metabolic response, and toxicity of UV-234 and UV-326 in larval zebrafish (Danio rerio)

Development of an analytical method and risk characterization for benzotriazole ultraviolet stabilizers in various foods

This study developed and validated an analytical method for quantifying benzotriazole ultraviolet stabilizers (BUVSs) in various foods commonly consumed in Korea, addressing a critical gap in the monitoring of these emerging contaminants in food matrices. The validation results of this gas chromatography-mass spectrometry method demonstrated high specificity, sensitivity, and precision, with limits of detection as low as 0.008-0.040 ng/g across various food types. Among the tested foods, BUVS contamination was highest in fatty matrices, with beef, eel, and mackerel showing elevated levels of UV-326, UV-327, and UV-328. Exposure assessments using dietary consumption data from KNHANES revealed that the average dietary intake of BUVSs posed low health risks, as margins of exposures exceeded the safety threshold of 100. This study emphasizes the importance of ongoing monitoring of persistent organic pollutants in high-fat and other food products to reduce potential bioaccumulation risks, ensuring food safety and public health protection.

Developmental and neurobehavioral toxicity of benzotriazole ultraviolet stabilizer UV-360 on zebrafish larvae

The presence of UV-360, a commonly utilized benzotriazole ultraviolet stabilizer, has been frequently detected in diverse environments and organisms. However, existing knowledge regarding the potential impacts of UV-360 exposure on organisms remains limited. To evaluate the influence of UV-360 exposure on zebrafish during their initial developmental phases. The study began with an assessment of the developmental impact of UV-360 on larval stages. Subsequently, the investigation focused on examining its effects on locomotor behaviors. Additionally, analyses were conducted on neuronal development, the expression of genes associated with neurotoxicity, and electrophysiological recordings. Finally, the research extended to an exploration of transcriptome-level gene expression profiles. Exposure to UV-360 exhibited significant adverse effects on larvae, evidenced by a marked reduction in hatching rate, decreased heart rate, and impaired development of total body length. Furthermore, UV-360 exposure induced notable behavioral alterations, malformations in spinal motor neuron axons, and a substantial decrease in both the area and volume of these axons. Additionally, the expression of neurotoxicity-related genes and electrophysiological spike activity were significantly altered by UV-360 exposure. Lastly, exposure to UV-360 triggered significant modifications in the transcriptomic profile of zebrafish larvae, with a considerable proportion of differentially expressed genes associated with signal transduction processes and the neuroactive ligand-receptor interaction pathway. The results of this study revealed a dose-dependent developmental and neurobehavioral toxicity associated with UV-360 exposure in zebrafish larvae. The observed modifications in neuroactive ligand-receptors and disruptions in neurotransmitter systems suggested a potential mechanism for the neurotoxicity induced by UV-360 exposure in zebrafish larvae. These findings contribute significantly to the understanding of the toxicological effects of UV-360 on zebrafish larvae and provide strong evidence to help clarify the mechanisms of UV-360-induced toxicity.

Metabolic variation and oxidative stress responses of clams (Ruditapes philippinarum) perturbed by ofloxacin exposure

Ofloxacin (OFL), one of the most widely used fluoroquinolone antibiotics, has been frequently detected in marine environments. Nonetheless, researchers are yet to focus on the effects of OFL on the benthos. In the present study, marine clams (Ruditapes philippinarum) were exposed to OFL (0.5, 50, and 500 μg/L) for 14 d, followed by a 7 d depuration period. The accumulation of OFL, antioxidative defense responses, neurotoxicity, burrowing behavior, and metabolomic changes in clams were evaluated. The results indicated that OFL could accumulate in clams, albeit with a low bioaccumulation capacity. The intermediate (50 μg/L) and high (500 μg/L) levels of OFL induced significant antioxidative responses in the gills and digestive glands of clams, mainly manifesting as the inhibition of catalase activities and the induction of superoxide dismutase and glutathione S-transferase activities, which ultimately elevated the content of malondialdehyde, causing oxidative damage. Furthermore, the significant induction of acetylcholinesterase activities was observed, coinciding with a significant increase in burrowing rates of clams. The high level of OFL affected glycerophospholipid, arachidonic acid, steroid hormone biosynthesis, unsaturated fatty acids biosynthesis, and glycolysis/glycogenesis metabolism. In conclusion, this study has contributed to the understanding of the physiological and biochemical effects and molecular toxicity mechanisms of OFL to marine bivalves.

Transcriptome Responses of the Soil-Dwelling Collembolan (Entomobrya proxima Folsom) to Fertilizer Type and Concentration

Soil collembolans have been regarded as the effective bioindicator of environmental changes. However, the physiological mechanisms through which collembolans respond to agricultural activities are largely unknown. Given the plasticity and sensitivity to environmental changes, even subtle responses can be quantified via transcriptomics. Therefore, the relevant in situ soil ecosystem and numerically dominant collembolan species Entomobrya proxima Folsom was selected to explore the dynamic responses to fertilizer type and concentration using transcriptome sequencing over three periods (6 h, 24 h and 10 d). The results showed that exposure duration caused significant alterations in gene expression profiles. At day 10 after exposure, gene expression patterns differed remarkably between the two fertilizer types and the control. Relative to organic fertilizer, the number of DEGs was increased by 114.31% under inorganic fertilizer, which declined with increasing inorganic fertilizer concentrations. Functional enrichment analysis was indicative of enhanced fatty acid and carbohydrate metabolism and reduced disease occurrence by organic fertilizer; however, an inhibited lipid synthesis process promoted susceptibility to infection, triggered oxidative stress, etc. by inorganic fertilizer. Overall, fertilizer addition changed the transcriptional pattern of the collembolan, potentially causing shifts in pathways related to metabolism, immunity, etc. In comparison to inorganic fertilizer, organic fertilizer impacted less on the gene expression patterns, implying that organic fertilizer application may be more beneficial to soil animal health.

Exposure Assessment of Benzotriazole Ultraviolet Absorbers in Plastic Sports Field Dust and Indoor Dust: Are Plastic Sports Fields High Exposure Scenarios?

Benzotriazole ultraviolet absorbers (BUVs), as emerging contaminants of extensive use, especially in plastic sports fields, have aroused increasing concern due to their potential human and environmental impacts. However, BUV exposure from plastic sports field dust is still unknown. This study compared BUVs in plastic sports field dust and indoor dust for the first time. The order of the geometric mean concentrations of the total BUVs (ΣBUVs) in plastic sports field dust was indoor badminton courts (11023 ng g-1) > basketball courts (4777 ng g-1) > plastic tracks (3779 ng g-1) > synthetic turf (1920 ng g-1) > tennis courts (689 ng g-1). The geometric mean concentrations of ΣBUVs in indoor dust (1150 ng g-1) were lower than those in most plastic sports field dust. The dominant BUV was 2-hydroxy-4-(octyloxy)benzophenone (UV-531) in plastic sports field dust, while 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-2H-benzotriazole-2-yl)phenol] (UV-360) was the dominant BUV in indoor dust. Releases from plastic track materials, sneaker soles, and friction between them might be important BUV sources in plastic track dust. The average estimated daily intakes of ΣBUVs from plastic sports field dust for general exercisers were lower than those from indoor dust, but those for exercisers with long time or professional athletes might be higher, potentially posing health risks.

Co-occurrence of azorubine and bisphenol A in beverages increases the risk of developmental toxicity: A study in zebrafish model

The prevalent use of Azorubine (E122) and the unintentional food additive, Bisphenol A (BPA), in ready-to-drink (RTD) beverages raises significant health concerns, especially for children. The combined impact on embryonic development must be explored despite individual safety assessments. Our investigation revealed that the combined exposure of E122 and BPA at beverage concentration significantly induces mortality and morphological deformities, including reduced growth, pericardial edema, and yolk sac edema. The co-exposure triggers oxidative stress, impairing antioxidant enzyme responses and resulting in lipid and cellular damage. Notably, apoptotic cells are observed in the neural tube and notochord of the co-exposed larvae. Critical genes related to the antioxidant response elements (nrf2, ho1, and nqo1), apoptosis activation (bcl2, bax, and p53), and pro/anti-inflammatory cytokines (nfkb, tnfa, il1b, tgfb, il10, and il12) displayed substantial changes, highlighting the molecular mechanisms. Behavior studies indicated hypo-locomotion with reduced thigmotaxis and touch response in co-exposed larvae, distinguishing it from individual exposures. These findings underscore the neurodevelopmental impacts of E122 and BPA at reported beverage concentrations, emphasizing the urgent need for comprehensive safety assessments, particularly for child consumption.

Neurotoxicity of Benzotriazole Ultraviolet Stabilizers in Teleost Fishes: A Review

Plastic additives that maintain integrity have been extensively studied for potential toxicity to fish; however, chemicals that protect polymers from (artificial) UV degradation are less studied. Benzotriazole UV stabilizers (BUVSs) are the most widely used UV stabilizers in plastics and are often used in sunscreens, cosmetics, paint, and food packaging. BUVSs can negatively affect aquatic wildlife when released into the environment via plastic degradation. In this review, we summarize the distribution of BUVSs globally and discuss neurotoxicological endpoints measured in fish to understand how these plastic additives can affect the neurological health of teleost fishes. BUVSs have been detected in aquatic environments at concentrations ranging from 0.05 up to 99,200 ng/L. Studies show that BUVSs affect behavioral responses and acetylcholinesterase activity, indicators of neurotoxicity. Our computational analysis using transcriptome data suggests certain pathways associated with neurodegeneration are responsive to exposure to BUVSs, like "Complement Activation in Alzheimer's Disease". Based on our review, we identify some research needs for future investigations: (1) molecular studies in the central nervous system to define precise mechanisms of neurotoxicity; (2) a wider range of tests for assessing aberrant behaviors given that BUVSs can affect the activity of larval zebrafish; and (3) histopathology of the nervous system to accompany biochemical analyses. These data are expected to enhance understanding of the neurotoxicity potential of benzotriazoles and other plastic additives.

Integrated transcriptomic and biochemical characterization of the mechanisms governing stress responses in soil-dwelling invertebrate (Folsomia candida) upon exposure to dibutyl phthalate

Dibutyl phthalate (DBP) is one of the most commonly utilized plasticizers and a frequently detected phthalic acid ester (PAE) compound in soil samples. However, the toxicological effects of DBP on soil-dwelling organisms remain poorly understood. This study employed a multi-biomarker approach to investigate the impact of DBP exposure on Folsomia candida's survival, reproduction, enzyme activity levels, and transcriptional profiles. Analyses of antioxidant biomarkers, including catalase (CAT) and glutathione S-transferase (GST), as well as detoxifying enzymes such as acetylcholinesterase (AChE), Cytochrome P450 (CYP450), and lipid peroxidation (LPO), revealed significant increases in CAT activity, GST levels, and CYP450 expression following treatment with various doses of DBP for 2, 4, 7, or 14 days. Additionally, LPO induction was observed along with significant AChE inhibition. In total, 3175 differentially expressed genes (DEGs) were identified following DBP treatment that were enriched in six Gene Ontology (GO) terms and 144 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including 85 upregulated and 59 downregulated primarily associated with lipid metabolism, signal transduction, DNA repair, and cell growth and death. Overall these results provide foundational insights for further research into the molecular mechanisms underlying responses of soil invertebrates to DBP exposure.

Maternal exposure to sunlight-irradiated graphene oxide induces neurodegeneration-like symptoms in zebrafish offspring through intergenerational translocation and genomic DNA methylation alterations

The physiochemical properties of graphene oxide may be affected by sunlight irradiation. However, the underlying mechanisms that alter the properties and subsequent intergenerational effects are not sufficiently investigate. Epigenetics is an early sensitive marker for the intergenerational effects of nanomaterial exposure due to the epigenetic memory. In this study, we investigate changes in the physicochemical properties and the intergenerational effects of maternal exposure to simulated sunlight-irradiated polyethyleneimine-functionalized graphene oxide (SL-PEI-GO). Results show that the physicochemical properties of polyethyleneimine-functionalized graphene oxide (PEI-GO) can be altered significantly by the oxidation of carbon atoms with unpaired electrons present in the defects and on the edges of PEI-GO by sunlight. First, the positive charges, sharp edges, defects and disordered structures of SL-PEI-GO make it translocate from maternal zebrafish to offspring, thus catalyzing the production of reactive oxygen species and damaging mitochondria directly. In addition, changes in DNA methylation reduce the expression of protocadherin1a, protocadherin19 and cadherin4, thus destroying cell membrane integrity, cell adhesion and Ca2+ binding. The alteration of DNA methylation induced by maternal exposure activates the Ca2+-CaMKK-brsk2a pathway, which catalyzes the phosphorylation of Tau and eventually results in the appearance of neurodegeneration-like symptoms, including the loss of neurons and neurobehavioral disorders. This study demonstrates that maternal exposure to SL-PEI-GO induces clear neurodegeneration-like symptoms in offspring through both the intergenerational translocation of nanomaterials and differential DNA methylation. These findings may provide new insights into the health risks of nanomaterials altered by nature conditions.