Long-term effects of embryonic exposure to benzophenone-3 on neurotoxicity and behavior of adult zebrafish

Ecotoxicological assessment of UV filters benzophenone-3 and TiO2 nanoparticles, isolated and in a mixture, in developing zebrafish (Danio rerio)

The increasing use of UV filters, such as benzophenone-3 (BP-3) and titanium dioxide nanoparticles (TiO2 NPs), has raised concerns regarding their ecotoxicological effects on the aquatic environment. The aim of the present study was to examine the embryo-larval toxicity attributed to BP-3 or TiO2 NPs, either alone or in a mixture, utilizing zebrafish (Danio rerio) as a model after exposure to environmentally relevant concentrations of these compounds. Zebrafish embryos were exposed to BP-3 (10, 100, or 1000 ng/L) or TiO2 NPs (1000 ng/L) alone or in a mixture (BP-3 10, 100, or 1000 ng/L plus 1000 ng/L of TiO2 NPs) under static conditions for 144 hr. After exposure, BP-3 levels were determined by high-performance liquid chromatography (HPLC). BP-3 levels increased in the presence of TiO2 NPs, indicating that the BP-3 degradation decreased in the presence of the NPs. In addition, in the presence of zebrafish, BP-3 levels in water decreased, indicating that zebrafish embryos and larvae might absorb BP-3. Data demonstrated that, in general, environmentally relevant concentrations of BP-3 and TiO2 NPs, either alone or in a mixture, did not significantly induce changes in heart and spontaneous contractions frequencies, levels of reactive oxygen species (ROS), morphological and morphometric parameters as well as mortality rates during 144 hr exposure. However, the groups exposed to TiO2 NPs alone and in a mixture with BP-3 at 10 ng/L exhibited an earlier significant hatching rate than the controls. Altogether, the data indicates that a potential ecotoxicological impact on the aquatic environment exists.

Neurotoxic and cardiotoxic effects of pyrogallol on catfish (Clarias gariepinus)

Pyrogallol, a botanical hydrolysable tannin, has diverse medical and industrial applications. Its impact on aquatic ecosystems and fish health has been previously studied, revealing histopathological, immunological, biochemical, and haematological alterations in African catfish (Clarias gariepinus). In this study, the neurotoxic potential of pyrogallol was assessed through a 15-day exposure of catfish to concentrations of 1, 5, or 10 mg/L. Enzyme activities such as acetylcholinesterase (AchE), monoamine oxidase (MAO), aldehyde oxidase (AO), and nitric oxide (NO) were measured in serum and brain, along with histopathological examinations in the brain and heart. Pyrogallol exposure led to decreased AchE activity in the brain and serum, increased serum MAO activity, elevated AO in both brain and serum, and suppressed NO levels. Morphological abnormalities and dose-dependent pathological alterations were observed in the brain and heart, including neuropile deformities, shrunken Purkinje cells, cardiomyocyte degeneration, and increased collagen fibers. This suggests that pyrogallol induces adverse effects in fish.

Biomonitoring of benzophenones in guano samples of wild bats in Poland

Benzophenones (BPs) are substances used in the production of sunscreens, cosmetics, and personal care products. However, there is a lack of knowledge of BPs in wild animals. Therefore, the study aimed to assess the concentration of selected BPs commonly used in the cosmetic industry in guano samples collected from 4 colonies of greater mouse-eared bats (Myotis myotis). Liquid chromatography with tandem mass spectrometry (LC-MS/MS) was used to determine guano concentrations of benzophenone 1 (BP-1), benzophenone 2 (BP-2), benzophenone 3 (BP-3) and benzophenone 8 (BP-8). BP-1 levels above the method quantification limit (MQL) were noted in 97.5% of samples and fluctuated from <0.1 ng/g to 259 ng/g (mean 41.50 ng/g, median 34.8). The second most common was BP-3, which fluctuated from <0.1 ng/g to 19 ng/g (mean 6.67 ng/g, median 5.05), and its levels higher than MQL were observed in 40% of samples. BP-2 and BP-8 concentrations did not exceed the method detection limit (0.04 ng/g) in any analyzed sample. There were visible differences in the BP-1 and BP-3 levels among the studied bat colonies. Mean BP-1 concentration fluctuated from 11.23±13.13 ng/g to 76.71±65.51 ng/g and differed significantly between the colonies. Mean BP-3 concentration fluctuated from 5.03±6.03 ng/g to 9.18±7.65 mg/g, but it did not differ significantly between the colonies. The results show that guano is a suitable matrix for the assessment of wildlife exposure to BPs. This could be particularly advantageous in protected species, where not disturbing and stressing the animals are crucial.

Toxicity comparison of benzophenone-3 and its metabolite benzophenone-8 in different tissues of zebrafish

Benzophenone-3 (BP-3) is a commonly used ultraviolet absorber that has the potential to accumulate in organisms, leading to toxicity. Benzophenone-8 (BP-8) is one of the major metabolites of BP-3. In this study, zebrafish were exposed to different concentrations of BP-3 and BP-8 (1 μg/L, 30 μg/L, and 300 μg/L) to investigate their accumulation and toxic effects in various tissues, including zebrafish brain, gut, and liver. The analysis focused on neurotoxicity, oxidative damage, inflammation, and gene expressions. The results showed that both BP-3 and BP-8 accumulated in the tissues, with the highest concentration observed in the gut, followed by the liver and brain. BP-8 exhibited a stronger ability to accumulate. In the brain, exposure to 1 μg/L of BP-3 and BP-8 promoted cortisol production, while higher exposures (30 μg/L and 300 μg/L) inhibited acetylcholinesterase activity and suppressed cortisol production. In the gut, both BP-3 and BP-8 exposures disrupted oxidative stress, inflammatory immunity, and apoptosis functions. In the liver, BP-3 and BP-8 affected hepatic metabolism, oxidative stress, apoptosis, and inflammatory immunity. Comparing gene expression in the brain, gut, and liver, it was found that BP-3 and BP-8 had a lower effect on gene expression in the brain, while the effect on the gut and liver was significantly higher. BP-8 generally had a higher effect than BP-3, which aligns with the observed accumulation pattern. These findings provide valuable insights for the risk assessment of BP-3 and BP-8 in the aquatic environment.

Embryotoxic Effects of Pesticides in Zebrafish (Danio rerio): Diflubenzuron, Pyriproxyfen, and Its Mixtures

Diflubenzuron (DFB) and pyriproxyfen (PPF) are larvicides used in crops to control insect plagues. However, these pesticides are known to impact non-target organisms like fish and mammals. Here, we aimed at assessing the embryotoxicity of purified DFB, PPF, and their mixtures in a non-target organism-zebrafish. Zebrafish embryos were exposed to different concentrations for 120 h: 0.025, 0.125, 0.25, 1.25, 2.5, and 10 mg/L of purified PPF and purified DFB, while we used 0.025 mg/L PPF + 10 mg/L DFB (Mix A), 0.125 mg/L PPF + 10 mg/L DFB (Mix B), and 0.25 mg/L PPF + 10 mg/L DFB (Mix C) for the mixtures of PPF + DFB. We observed mortality, teratogenicity, and cardiotoxicity. For the neurotoxicity tests and evaluation of reactive oxygen species (ROS) levels in the brain, embryos were exposed for 120 h to 0.379 and 0.754 mg/L of PPF and 0.025 and 0.125 mg/L of DFB. We established the LC50 for PPF as 3.79 mg/L, while the LC50 for DFB was not determinable. Survival and hatching were affected by PPF concentrations above 0.125 mg/L, DFB concentrations above 1.25 mg/L, and the lower pesticide mixtures. PPF exposure and mixtures induced different types of malformations, while a higher number of malformations were observed for the mixtures, suggesting a potentiating effect. Pesticides diminished avoidance responses and increased the levels of ROS across all concentrations, indicating neurotoxicity. Our findings underscore the detrimental impact of PPF and DFB exposure, spanning from biochemistry to morphology. There is a critical need to reconsider the global use of these pesticides and transition to more ecologically friendly forms of pest control, raising an alarm regarding repercussions on human and animal health and well-being.