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.

Due to the growing concern about the presence of microplastics (MP) in the environment, the number of studies evaluating the toxicity of these small persistent particles on different marine species has increased in recent years. Few studies have addressed their impact on marine phytoplankton, a subject of great concern since they are primary producers of the aquatic food web. The aim of this study is to unravel the cytotoxicity of 2.5 μg mL−1 unlabelled amino-modified polystyrene beads of different sizes (0.5 and 2 μm) on the marine diatom Chaetoceros neogracile. In addition to traditional growth and photosynthesis endpoints, several physiological and biochemical parameters were monitored every 24 h in C. neogracile cells by flow cytometry during their exponential growth (72 h). Dynamic Light Scattering measurements revealed the strong aggregation and the negative charge of the beads assayed in the culture medium, which seemed to minimize particle interaction with cells and potentially associated impacts. Indeed, MP were not attached to the microalgal cell wall, as evidenced by scanning electron micrographs. Cell growth, morphology, photosynthesis, reactive oxygen species levels and membrane potential remained unaltered. However, exposure to MP significantly decreased the cellular esterase activity and the neutral lipid content. Microalgal oil bodies could serve as an energy source for maintaining a healthy cellular status. Thus, MP-exposed cells modulate their energy metabolism to properly acclimate to the stress conditions.

International audience | Methotrexate is an antineoplastic folate analog of high environmental concern, due to its low biodegradability and toxicological properties. This study focused on its photodegradation under two irradiation conditions, aiming to be representative of environment (300-450 nm) and drinking water treatment (254 nm). The photodegradation experiments were conducted at two pH, to vary the methotrexate ionization state and to produce a large variety of transformation products (TPs). The degradation kinetics determined through LC-UV monitoring were contrasted according to pH and irradiation wavelength. However, the quantum yields were independent of ionization state at 254 nm and the changes in kinetics at higher wavelengths were attributed to a change in the degradation mechanism. The TPs formed during the reactions were identified by UHPLC-MS/MS, using both the positive and negative modes. Among the eleven proposed structures, five were described as methotrexate TPs for the first time. The TPs result from N-demethylation, glutamic acid oxidation, and C-N cleavage, all of them leading to further degraded photoproducts presenting modified or lost glutamic acid part. This was made possible thanks to the negative mode, which allowed the exploration of the glutamic acid moiety modifications. Cytotoxicity assessment on A549 cancer cells demonstrated that all photoproducts formed at pH 7 were less toxic than the parent compound.

Nowadays, marine ecosystems are under severe threat from the simultaneous presence of multiple stressors, including microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene (B[a]P). In addition to their presence in various marine compartments, there are increasing concerns on the potential capacity of MPs to sorb, concentrate and transfer these pollutants in the environment. Although their ecotoxicological impacts are currently evident, few works have studied the combined effects of these contaminants. Therefore, the major purpose of this work was to assess the toxicity of environmental relevant concentrations of MPs (<30 μm) and B[a]P, alone and in mixture, in the seaworm Hediste diversicolor by exploring their accumulation and hazardous biological effects for 3 and 7 days. Environmental MPs were able to increase B[a]P in a time-dependent manner. The obtained results showed that individual treatments, as well as co-exposure to contaminants, caused cytotoxicity and genotoxicity in the cœlomic fluid cells, while oxidative stress effects were observed at tissue and gene levels associated with alteration in neurotransmission. Overall, our findings provide additional clues about MPs as organic pollutant vectors in the marine environment, and contribute to a clearer understanding of their toxicological risk to aquatic invertebrates.

Percolation of water through oily sludge during storage and handling of the sludge can cause soil and groundwater contamination. In this study, oily sludge from a refinery was equilibrated with water to obtain the water-soluble fraction (WSF) of oily sludge. The WSF had dissolved organic carbon (DOC) of 166 mg/L. Human cell line-based toxicity assay revealed IC₅₀ of 41 mg/L indicating its toxic nature. The predominant compounds in WSF of oily sludge included isomers of methyl, dimethyl and trimethyl quinolines and naphthalenes along with phenol derivatives and other polynuclear aromatic hydrocarbons (PAHs). Biodegradation of WSF of oily sludge was studied using a consortium of Rhodococcus ruber, Bacillus sp. and Bacillus cereus isolated from the refinery sludge. The consortium of the three strains resulted in 70% degradation over 15 days with a first-order degradation rate of 0.161 day⁻¹. Further analysis of the WSF was performed using the stir-bar sorptive extraction (SBSE) followed by GCxGC-TOF MS employing a PDMS Twister. The GCxGC analysis showed that Bacillus cereus was capable of degrading the quinoline, phenol and naphthalene derivatives in WSF of oily sludge at a faster rate compared to pyridine and benzoquinoline derivatives. Quinoline, phenol, biphenyl, naphthalene, pyridine and benzoquinolines derivatives in the WSF of oily sludge were reduced by 87%, 92%, 88%, 77%, 40% and 62%, respectively with respect to the controls. The WSF of oily sludge contained, n-alkanes, ranging from n-C12 to n-C18 which were removed within 2 days of biodegradation.

Trace elements (TEs) from various natural and anthropogenic activities contaminate the agricultural water and soil environments. The use of nanoparticles (NPs) as nano-fertilizers or nano-pesticides is gaining popularity worldwide. The NPs-mediated fertilizers encourage the balanced availability of essential nutrients to plants compared to traditional fertilizers, especially in the presence of excessive amounts of TEs. Moreover, NPs could reduce and/or restrict the bioavailability of TEs to plants due to their high sorption ability. In this review, we summarize the potential influence of NPs on plant physiological attributes, mineral absorption, and TEs sorption, accumulation, and translocation. It also unveils the NPs-mediated TE scavenging-mechanisms at plant and soil interface. NPs immobilized TEs in soil solution effectively by altering the speciation of TEs and modifying the physiological, biochemical, and biological properties of soil. In plants, NPs inhibit the transfer of TEs from roots to shoots by inducing structural modifications, altering gene transcription, and strengthening antioxidant defense mechanisms. On the other hand, the mechanisms underpinning NPs-mediated TEs absorption and cytotoxicity mitigation differ depending on the NPs type, distribution strategy, duration of NP exposure, and plants (e.g., types, varieties, and growth rate). The review highlights that NPs may bring new possibilities for resolving the issue of TE cytotoxicity in crops, which may also assist in reducing the threats to the human dietary system. Although the potential ability of NPs in decontaminating soils is just beginning to be understood, further research is needed to uncover the sub-cellular-based mechanisms of NPs-induced TE scavenging in soils and absorption in plants.

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.

Inhalation represents the most prevalent route of exposure with Thorium-232 compounds (Th-nitrate/Th-dioxide)/Th-containing dust in real occupational scenario. The present study investigated the mechanism of Th response in normal human alveolar epithelial cells (WI26), exposed to Th-nitrate or colloidal Th-dioxide (1–100 μg/ml, 24–72 h). Assessment in terms of changes in cell morphology, cell proliferation (cell count), plasma membrane integrity (lactate dehydrogenase leakage) and mitochondrial metabolic activity (MTT reduction) showed that Th-dioxide was quantitatively more deleterious than Th-nitrate to WI26 cells. TEM and immunofluorescence analysis suggested that Th-dioxide followed a clathrin/caveolin-mediated endocytosis, however, membrane perforation/non-endocytosis seemed to be the mode of Th internalization in cells exposed to Th-nitrate. Th-estimation by ICP-MS showed significantly higher uptake of Th in cells treated with Th-dioxide than with Th-nitrate at a given concentration. Both Th-dioxide and nitrate were found to increase the level of reactive oxygen species, which seemed to be responsible for lipid peroxidation, alteration in mitochondrial membrane potential and DNA-damage. Amongst HSPs, the protein levels of HSP70 and HSP90 were affected differentially by Th-nitrate/dioxide. Specific inhibitors of ATM (KU55933) or HSP90 (17AAG) were found to increase the Th- cytotoxicity suggesting prosurvival role of these signaling molecules in rescuing the cells from Th-toxicity.

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.

Triclosan (TCS), an emergent pollutant, is raising a global concern due to its toxic effects on organisms and aquatic ecosystems. The non-availability of proven treatment technologies for TCS remediation is the central issue stressing thorough research on understanding the underlying mechanisms of toxicity and assessing vital biomarkers in the aquatic organism for practical monitoring purposes. Given the unprecedented circumstances during COVID 19 pandemic, a several-fold higher discharge of TCS in the aquatic ecosystems cannot be considered a remote possibility. Therefore, identifying potential biomarkers for assessing chronic effects of TCS are prerequisites for addressing the issues related to its ecological impact and its monitoring in the future. It is the first holistic review on highlighting the biomarkers of TCS toxicity based on a comprehensive review of available literature about the biomarkers related to cytotoxicity, genotoxicity, hematological, alterations of gene expression, and metabolic profiling. This review establishes that biomarkers at the subcellular level such as oxidative stress, lipid peroxidation, neurotoxicity, and metabolic enzymes can be used to evaluate the cytotoxic effect of TCS in future investigations. Micronuclei frequency and % DNA damage proved to be reliable biomarkers for genotoxic effects of TCS in fishes and other aquatic organisms. Alteration of gene expression and metabolic profiling in different organs provides a better insight into mechanisms underlying the biocide's toxicity. In the concluding part of the review, the present status of knowledge about mechanisms of antimicrobial resistance of TCS and its relevance in understanding the toxicity is also discussed referring to the relevant reports on microorganisms.