The rising global demand for palm oil and its associated products has led to increased numbers of palm oil refineries with its attendant effluent discharge. Many researches have confirmed the ecological disruptive potentiality of Palm Oil Mill Effluent (POME), still further attention has to be directed at POME’s potential genotoxicity. The present study has made physico-chemical and genotoxicity assessments of POME from a corporate refinery in Nigeria, using the American Public Health Association (APHA) procedures along with Allium cepa root assay. Allium cepa roots were grown in graduated concentrations of POME and the roots were analyzed for chromosomal aberrations. Results suggest that POME caused growth inhibitions and chromosomal aberrations in A. cepa roots. with mitotic index of A. cepa roots dropping as POME concentrations were increased. The chromosomal aberrations induced in A. cepa were vagrant, sticky chromosomes, bi-nucleated cells, and C-mitosis. These results indicate that palm oil mill effluent is not only capable of causing ecological disruptions in the receiving environment, but is also potentially genotoxic to resident organisms. It is recommended that if effluents from palm oil mill refineries cannot be converted to other useful products and ought to be disposed of, it should first be properly treated and tested for genotoxicity.

International audience | The intestinal epithelium is a functional and physical barrier formed by a cell monolayer that constantly differentiates from a stem cell in the crypt. This is the first target for food contaminants, especially mycotoxins. Deoxynivalenol (DON) is one of the most prevalent mycotoxins. This study compared the effects of DON (0-100 μM) on proliferative and differentiated intestinal epithelial cells. Three cell viability assays (LDH release, ATP content and neutral red uptake) indicated that proliferative Caco-2 cells are more sensitive to DON than differentiated ones. The establishment of transepithelial electrical resistance (TEER), as a read out of the differentiation process, was delayed in proliferative cells after exposure to 1 μM DON. Transcriptome analysis of proliferative and differentiated exposure to 0-3 μM DON for 24 h revealed 4862 differentially expressed genes (DEG) and indicated an effect of both the differentiation status and the DON treatment. KEGG enrichment analysis indicated involvement of metabolism, ECM receptors and tight junctions in the differentiation process, while ribosome biogenesis, mRNA surveillance, and the MAPK pathway were involved in the response to DON. The number of differentially expressed genes and the amplitude of the effect were higher in proliferative cells exposed to DON than that in differentiated cells. In conclusion, our study shows that proliferative cells are more susceptible than differentiated ones to DON and that the mycotoxin delays the differentiation process.

The association between polycyclic aromatic hydrocarbons (PAHs) and male reproductive dysfunction has attracted increasing attention. The purpose of this study was to compare the male reproductive toxicity of multiple PAHs and to investigate the underlying molecular mechanisms. TM4 cells (mouse testicular Sertoli cells, SCs) were treated with benzo(a)pyrene (BaP), pyrene (Py), fluoranthene (Fl) and phenanthrene (Phe) (0, 0.1, 1, 10, 50, or 100 μM) for varying time points (4, 12, 24, or 48 h), and male C57BL/6 mice were administered BaP and Py (0, 10, 50, or 100 mg/kg body weight) for 14 days based on the cell experimental results. Histopathological examination, western blotting, ELISA, biochemical assays, RT–PCR, flow cytometry, JC-1 staining and trans-epithelium electrical resistance (TEER) measurements were used to assess apoptosis, blood-testis barrier (BTB) integrity, intracellular calcium ([Ca²⁺]ᵢ) concentrations and oxidative stress (OS). The results revealed that the mRNA levels and enzymatic activities of CYP450 and GST family members; levels of ROS, MDA, cleaved caspase 3 (c-caspase 3), caspase 9, Bax, and cytochrome C (CytC); and numbers of TUNEL-positive cells were significantly increased by BaP and Py, while levels of AhR, GSH, SOD, CAT, Bcl-2 and ΔΨm were decreased. Additionally, BaP and Py notably interfered with tight junctions (TJs) and adherens junctions (AJs) in the BTB. Intriguingly, BaP, but not Py, induced [Ca²⁺]ᵢ overload and gap junction (GJ) destruction. There was no dramatic effect of Fl and/or Phe on any of the above parameters except that slight cytotoxicity was observed with higher doses of Fl. Collectively, these findings showed that BaP and Py elicited SC apoptosis and BTB disruption involving mitochondrial dysfunction and OS, but [Ca²⁺]ᵢ fluctuation and GJ injury were only observed with BaP-induced reproductive toxicity. The male reproductive toxicity of the selected PAHs was ranked in the order of BaP > Py > Fl > Phe.

We investigated the biological response of soluble organic fraction (SOF) and water-soluble fraction (WSF) extracted from particulate matter (PM) emitted by an automotive diesel engine operating in a representative urban driving condition. The engine was fueled with ultra-low sulfur diesel (ULSD), and its binary blends by volume with 13% of butanol (Bu13), and with hydrotreated vegetable oil (HVO) at 13% (HVO13) and 20% (HVO20). Cytotoxicity, genotoxicity, oxidative DNA damage and ecotoxicity tests were carried out, and 16 polycyclic aromatic hydrocarbons (PAH) expressed as tbenzo(a)pyrene total toxicity equivalent (BaP-TEQ) were also analyzed. The Hepatocarcinoma epithelial cell line (HepG2) was exposed to SOF for 24 h and analyzed using comet assay, with the inclusion of formamidopyrimidine DNA glycosylase (FPG) and endonuclease III (Endo III) to recognize oxidized DNA bases. The WSF was evaluated through acute ecotoxicity tests with the aquatic microcrustacean Daphnia pulex (D. Pulex). Results showed that there was no cytotoxic activity for all tested SOF concentrations. Genotoxic responses by all the SOF samples were at same level, except for the HVO13 which was weaker in the absence of the enzymes. The addition of the FPG and Endo III enzymes resulted in a significant increase in the comet tail, indicating that the DNA damage from SOF for all tested fuel blends involves oxidative damage including a higher level of oxidized purines for ULSD and Bu13 in comparison with HVO blends, but the oxidized pyrimidines for HVO blends were slightly higher compared to Bu13. The WSF did not show acute ecotoxicity for any of the fuels. Unlike other samples, Bu13-derived particles significantly increase the BaP-TEQ. The contribution to the genotoxic activity and oxidative DNA from SOF was not correlated to BaP-TEQ, which means that the biological activity of PM might be affected also by other toxic compounds present in particulate phase.

A large amount of disposable plastic face masks (DPFs) is produced and used during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, which results in an inevitable consequence of the dramatic increase of DPFs waste. However, the impact of DPFs exposure to the environment on their toxicity is rarely considered. In this study, a range of 76–276 items/L microplastics (MPs) was detected in the DPFs leachates, and fibrous (> 80.3%) and polypropylene (PP, > 89.2%) MPs were dominant. Co, Cu, Ni, Sr, Ti and Zn, were commonly detected in all leachates of the tested DPFs. Organics, such as acetophenone, 2,4-Di-tert-butylphenol, benzothiazole, bisphenol-A and phthalide, were found in the DPFs leachate, which were including organic solvents and plasticizer. Besides, we first found an emerging environmental risk substance, namely environmentally persistent free radicals (EPFRs), was generated in the DPFs leachates. The characteristic g-factors of the EPFRs was in a range of 2.003–2.004, identified as mixture of carbon- and oxygen-centered radicals. By means of in vitro toxicity assay, the DPFs leachate were confirmed to cause cytotoxicity and oxidative stress. Significantly, it is found that the formed EPFRs could contribute more toxic effects. Furthermore, when compared to N95 respirators, the tested surgical masks tend to release more MPs, leach more metals and organics, and generate more EPFRs. Surgical masks were thus showed higher risk than N95 respirators after exposure to water. This work highlights the importance of understanding the chemical complexity and possible toxicity of DPFs for their risk assessment.

The presence of microplastics in the various food web raised concerns on human health, but little is known about the target cells and mechanism of toxicity of microplastics. In this study, we evaluated the toxicity of microplastics using relevant cell lines to the oral route of exposure. Approximately 100 μm-sized fragment-type polypropylene (PP) and polystyrene (PS) particles were prepared by sieving after pulverization and further applied the accelerated weathering using ultraviolet and heat. Thus, the panel of microplastics includes fresh PP (f-PP), fresh PS (f-PS), weathered PP (w-PP), and weathered PS (w-PS). The spherical PS with a similar size was used as a reference particle. Treatment of all types of PP and PS did not show any toxic effects to the Caco-2 cells and HepG2 cells. However, the treatment of microplastics to THP-1 macrophages showed significant toxicity in the order of f-PS > f-PP > w-PS > w-PP. The weathering process significantly reduced the reactive oxygen species (ROS) generation potential of both microplastics because the weathered microplastics have an increased affinity to bind serum protein which acts as a ROS scavenger. The intrinsic ROS generation potential of microplastics showed a good correlation with the toxicity endpoints including cytotoxicity and pro-inflammatory cytokines in THP-1 macrophages. In conclusion, the results of this study suggest that the target cell type of microplastics via oral administration can be macrophages and the pathogenic factor to THP-1 macrophages is the intrinsic ROS generation potential of microplastics. Nevertheless, the toxic effect of microplastics tested in this study was much less than that of nano-sized particles.

The surface modifications of nanoparticles (NPs), are well-recognized parameters that affect the toxicity, while there has no study on toxicity of Al₂O₃ NPs with different surface modification. Therefore, for the first time, this study pays attention to evaluating the toxicity and potential mechanism of pristine Al₂O₃ NPs (p-Al₂O₃), hydrophilic (w-Al₂O₃) and lipophilic (o-Al₂O₃) modifications of Al₂O₃ NPs both in vitro and in vivo. Applied concentrations of 10, 20, 40, 80,100 and 200 μg/mL for 24 h exposure on Caenorhabditis elegans (C. elegans), while 100 μg/mL of Al₂O₃ NPs significantly decreased the survival rate. Using multiple toxicological endpoints, we found that o-Al₂O₃ NPs (100 μg/mL) could induce more severe toxicity than p-Al₂O₃ and w-Al₂O₃ NPs. After uptake by C. elegans, o-Al₂O₃ NPs increased the intestinal permeability, easily swallow and further destroy the intestinal membrane cells. Besides, cytotoxicity evaluation revealed that o-Al₂O₃ NPs (100 μg/mL) are more toxic than p-Al₂O₃ and w-Al₂O₃. Once inside the cell, o-Al₂O₃ NPs could attack mitochondria and induce the over-production of reactive oxygen species (ROS), which destroy the intracellular redox balance and lead to apoptosis. Furthermore, the transcriptome sequencing and RT-qPCR data also demonstrated that the toxicity of o-Al₂O₃ NPs is highly related to the damage of cell membrane and the imbalance of intracellular redox. Generally, our study has offered a comprehensive sight to the adverse effects of different surface modifications of Al₂O₃ NPs on environmental organisms and the possible underlying mechanisms.

Cetaceans accumulate persistent and toxic substances such as polybrominated diphenyl ethers in their tissue. PBDEs are ubiquitous in marine environments, and their exposure to mammals is linked to numerous health effects such as endocrine disruption, neurotoxicity, carcinogenicity, and fetal toxicity. However, the toxicological effects and mechanism of toxicity in cetaceans remains poorly understood. The effects of BDE-47 (0.1–0.5 μg mL⁻¹), BDE-100 (0.1–0.5 μg mL⁻¹), and BDE-209 (0.25–1.0 μg mL⁻¹) exposure on cell viability, oxidative stress, mitochondrial structure, and apoptosis were evaluated using a recently established pantropical spotted dolphin (Stenella attenuata) skin fibroblast cell line (PSD-LWHT) as an in vitro model. However, the production of reactive oxygen species (ROS) increased following exposure to 1.0 μg mL⁻¹ PBDE while superoxide anion, hydroxyl radicals, and inducible nitric oxide increased in a dose-dependent manner. At 0.5–1.0 μg mL⁻¹, PBDEs significantly reduced the mitochondrial membrane potential. In addition, exposure to BDE-47 and -209 significantly affected mitochondrial structure as well as cell signaling and transduction compared to BDE-100. Although PBDE exposure did not affect cell viability, a significant increase in cell apoptosis markers (Bcl2 and caspase-9) was observed. This study demonstrated that BDE-47, -100, and −209 congeners might cause cytotoxic and genotoxic effects as they play a crucial role in the dysregulation of oxidative stress and alteration of mitochondrial and cell membrane structure and activity in the fibroblast cells. Hence, these results suggest that PBDEs might have adverse health effects on cetaceans inhabiting contaminated marine environments.

Fipronil, a phenyl-pyrazole insecticide, has a wide range of uses, from agriculture to veterinary medicine. Due to its large-scale applications, the risk of environmental and occupational exposure and bioaccumulation raises concerns. Moreover, relatively little is known about the intracellular mechanisms of fipronil in trophoblasts and the endometrium involved in implantation. Here, we demonstrated that fipronil reduced the viability of porcine trophectoderm and luminal epithelial cells. Fipronil induced cell cycle arrest at the sub-G1 phase and apoptotic cell death through DNA fragmentation and inhibition of DNA replication. These reactions were accompanied by homeostatic changes, including mitochondrial depolarization and cytosolic calcium depletion. In addition, we found that exposure to fipronil compromised the migration and implantation ability of pTr and pLE cells. Moreover, alterations in PI3K-AKT and MAPK-ERK1/2 signal transduction were observed in fipronil-treated pTr and pLE cells. Finally, the antiproliferative and apoptotic effects of fipronil were also demonstrated in 3D cell culture conditions. In summary, our results suggest that fipronil impairs implantation potentials in fetal trophectoderm and maternal endometrial cells during early pregnancy.

Fish embryos, as an endogenous system, strictly regulate an energy metabolism that is particularly sensitive to environmental pressure. This study used orange-spotted grouper embryos and stable isotope ⁶⁷Zn to test the hypothesis that waterborne Zn exposure had a significant effect on energy metabolism in embryos. The fish embryos were exposed to a gradient level of waterborne ⁶⁷Zn, and then sampled to quantify ⁶⁷Zn bioaccumulation and mRNA expressions of key genes involved glucose metabolism. The results indicated that the bioaccumulated ⁶⁷Zn generally increased with increasing waterborne ⁶⁷Zn concentrations, while it tended to be saturated at waterborne ⁶⁷Zn > 0.7 mg L⁻¹. As we hypothesized, the expression of PK and PFK gene involved glycolysis pathway was significantly up-regulated under waterborne ⁶⁷Zn exposure >4 mg L⁻¹. Waterborne ⁶⁷Zn exposure >2 mg L⁻¹ significantly suppressed PCK and G6PC gene expression involved gluconeogenesis pathway, and also inhibited the AKT2, GSK-3beta and GLUT4 genes involved Akt signaling pathway. Our findings first characterized developmental stage-dependent Zn uptake and genotoxicity in fish embryos. We suggest fish embryos, as a small-scale modeling biosystem, have a large potential and wide applicability for determining cytotoxicity/genotoxicity of waterborne metal in aquatic ecosystem.