Explore the vast range of titles available.

The evaluation of genotoxicity plays an important role within hazard identification and risk assessment of chemicals and consumer products. For genotoxicity assessment, in vitro hepatic cells are often used as they have retained certain level of xenobiotic metabolic activity. However, current protocols are designed for the use on 2D monolayer models that are associated with several limitations due to the lack of numerous biological functions, which results in the loss of many hepatic properties. In this respect, an attractive alternative are three-dimensional (3D) models. The aim of our study was to develop physiologically more relevant 3D cell model (spheroids) from the human hepatocellular carcinoma (HepG2) cell line for genotoxicity testing. The spheroids were prepared by the forced floating method, which had been optimized for the production of a large number of uniform spheroids. The sensitivity of the spheroids to detect genotoxicity was determined by the comet assay after the exposure of spheroids to non-cytotoxic concentrations of model indirect acting genotoxic compounds, namely polycyclic aromatic hydrocarbon (B(a)P), mycotoxin (AFB1), two heterocyclic aromatic amines (PhIP and IQ) and a direct acting etoposide (ET). All five tested compounds concentration dependently induced DNA damage. Higher sensitivity of 3D cell model compared to 2D monolayer culture was noticed particularly for detection of the genotoxicity of the heterocyclic aromatic amines and BaP. Deregulation of mRNA expression (qPCR) by genotoxic compounds revealed that HepG2 cells in 3D express important genes encoding phase I and II metabolic enzymes, as well as DNA damage responsive genes in an inducible form. The newly developed HepG2 3D model shows improved sensitivity for detecting genotoxic compounds compared to 2D cultures and can provide a suitable experimental model for genotoxicity assessment.

Bisphenol A (BPA) is, due to its widespread use including the production of plastic materials, an ubiquitous pollutant in the aquatic environment. Due to evidence of adverse BPA effects on the environment and human health, its use has been restricted and replaced by analogues such as bisphenol F (BPF). This study examined the toxicity of BPA, BPF and their mixture towards primary producers, the eukaryotic green alga Pseudokirchneriella subcapitata and the prokaryotic cyanobacterium Synechococcus leopoliensis. The results demonstrated that S. leopoliensis is more sensitive than P. subcapitata , whereas toxic potential of the two BPs is comparable and represents comparable hazard for phytoplankton. The toxicity of the binary mixture was predicted by different models (concentration addition, independent action, combination index and the isobologram method) and compared to experimental data. Additive effect was observed in P. subcapitata over the whole effect concentration range (EC 5 –EC 90 ), whereas in S. leopoliensis , no pronounced combined effect was observed. The environmental risk characterisation based on the comparison of reported concentrations of BPA and BPF in surface waters to the predicted no-effect concentration values obtained in this study showed that at certain industrial areas, BPA represents environmental risk, whereas BPF does not. However, BPF concentrations in aquatic environment are expected to increase in the future. To enable environmental risk assessment of BP analogues, more data on the toxicity to aquatic species, including combined effect, as well as data on their occurrence in the aquatic environment are needed. Graphical abstract

In genetic toxicology, there is a trend against the increased use of in vivo models as highlighted by the 3R strategy, thus encouraging the development and implementation of alternative models. Two-dimensional (2D) hepatic cell models, which are generally used for studying the adverse effects of chemicals and consumer products, are prone to giving misleading results. On the other hand, newly developed hepatic three-dimensional (3D) cell models provide an attractive alternative, which, due to improved cell interactions and a higher level of liver-specific functions, including metabolic enzymes, reflect in vivo conditions more accurately. We developed an in vitro 3D cell model from the human hepatocellular carcinoma (HepG2) cell line. The spheroids were cultured under static conditions and characterised by monitoring their growth, morphology, and cell viability during the time of cultivation. A time-dependent suppression of cell division was observed. Cell cycle analysis showed time-dependent accumulation of cells in the G0/G1 phase. Moreover, time-dependent downregulation of proliferation markers was shown at the mRNA level. Genes encoding hepatic markers, metabolic phase I/II enzymes, were time-dependently deregulated compared to monolayers. New knowledge on the characteristics of the 3D cell model is of great importance for its further development and application in the safety assessment of chemicals, food products, and complex mixtures.

The Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re‐evaluating the safety of gellan gum (E 418) as a food additive. Following the conceptual framework for the risk assessment of certain food additives re‐evaluated under Commission Regulation (EU) No 257/2010, the Panel considered that adequate exposure and toxicity data were available. Based on the reported use levels, a refined exposure of up to 72.4 mg/kg body weight (bw) per day in toddlers at the 95th percentile was estimated. Gellan gum is unlikely to be absorbed intact and would not be fermented by human intestinal microbiota. There is no concern with respect to carcinogenicity and genotoxicity. No adverse effects were reported in chronic studies at the highest doses tested in mice and rats (3,627 and 1,460 mg gellan gum/kg bw per day, respectively). Repeated oral intake up to 200 mg/kg bw per day for 3 weeks had no adverse effects in humans. The Panel concluded that there is no need for a numerical acceptable daily intake (ADI) for gellan gum (E 418), and that there is no safety concern at the refined exposure assessment for the reported uses and use levels of gellan gum (E 418) as a food additive. The Panel recommended to better define the specifications of gellan gum including the absence of viable cells of the microbial source and the presence of polyhydroxybutyrate (PHB), protein and residual bacterial enzymatic activities.

Benzalkonium chloride (BAC) is one of the most common ingredients of the disinfectants. It is commonly detected in surface and wastewaters where it can interact with the residues of pharmaceuticals that are also common wastewater pollutants. Among the latter, the residues of antineoplastic drugs are of particular concern as recent studies showed that they can induce adverse effect in aquatic organisms at environmentally relevant concentrations. Ecotoxicity of BAC as an individual compound and in a binary mixture with an antineoplastic drug 5-fluorouracil (5-FU) was determined towards alga a representative of primary producers The toxicity of the BAC+5-FU binary mixture was predicted by the two basic models: concentration addition (CA) and independent action (IA), and compared to the experimentally determined toxicity. Additionally combination index (CI) was calculated to determine the type of interaction. After 72 h exposure to BAC a concentration dependent growth inhibition of was observed with an EC 0.255 mg/L. Comparing the predicted no effect concentration to the measured concentrations in the surface waters indicate that BAC at current applications and occurrence in aquatic environment may affect algal populations. The measured toxicity of the mixture was higher from the predicted and calculated CI confirmed synergistic effect on the inhibition of algal growth, at least at EC concentration. The observed synergism may have impact on the overall toxicity of wastewaters, whereas it is less likely for general environments because the concentrations of 5-FU are several orders of magnitude lower from its predicted no effect concentration. These results indicate that combined effects of mixtures of disinfectants and antineoplastic drugs should be considered in particular when dealing with environmental risk assessment as well as the management of municipal and hospital wastewaters.

Ever-expanding environmental pollution is causing a rise in cyanobacterial blooms and the accumulation of plastics in water bodies. Consequently, exposure to mixtures of cyanotoxins and plastic-related contaminants such as bisphenols (BPs) is of increasing concern. The present study describes genotoxic effects induced by co-exposure to one of the emerging cyanotoxins—cylindrospermopsin (CYN)—(0.5 µg/mL) and BPs (bisphenol A (BPA), S (BPS), and F (BPF); (10 µg/mL)) in HepG2 cells after 24 and 72 h of exposure. The cytotoxicity was evaluated with an MTS assay and genotoxicity was assessed through the measurement of the induction of DNA double strand breaks (DSB) with the γH2AX assay. The deregulation of selected genes (xenobiotic metabolic enzyme genes, DNA damage, and oxidative response genes) was assessed using qPCR. The results showed a moderate reduction of cell viability and induction of DSBs after 72 h of exposure to the CYN/BPs mixtures and CYN alone. None of the BPs alone reduced cell viability or induced DSBs. No significant difference was observed between CYN and CYN/BPs exposed cells, except with CYN/BPA, where the antagonistic activity of BPA against CYN was indicated. The deregulation of some of the tested genes (CYP1A1, CDKN1A, GADD45A, and GCLC) was more pronounced after exposure to the CYN/BPs mixtures compared to single compounds, suggesting additive or synergistic action. The present study confirms the importance of co-exposure studies, as our results show pollutant mixtures to induce effects different from those confirmed for single compounds.

Titanium dioxide (TiO(2)) is considered as an inert and safe material and has been used in many applications for decades. However, with the development of nanotechnologies TiO(2) nanoparticles, with numerous novel and useful properties, are increasingly manufactured and used. Therefore increased human and environmental exposure can be expected, which has put TiO(2) nanoparticles under toxicological scrutiny. Mechanistic toxicological studies show that TiO(2) nanoparticles predominantly cause adverse effects via induction of oxidative stress resulting in cell damage, genotoxicity, inflammation, immune response etc. The extent and type of damage strongly depends on physical and chemical characteristics of TiO(2) nanoparticles, which govern their bioavailability and reactivity. Based on the experimental evidence from animal inhalation studies TiO(2) nanoparticles are classified as \"possible carcinogenic to humans\" by the International Agency for Research on Cancer and as occupational carcinogen by the National Institute for Occupational Safety and Health. The studies on dermal exposure to TiO(2) nanoparticles, which is in humans substantial through the use of sunscreens, generally indicate negligible transdermal penetration; however data are needed on long-term exposure and potential adverse effects of photo-oxidation products. Although TiO(2) is permitted as an additive (E171) in food and pharmaceutical products we do not have reliable data on its absorption, distribution, excretion and toxicity on oral exposure. TiO(2) may also enter environment, and while it exerts low acute toxicity to aquatic organisms, upon long-term exposure it induces a range of sub-lethal effects. Until relevant toxicological and human exposure data that would enable reliable risk assessment are obtained, TiO(2) nanoparticles should be used with great care.

Over the past 20 years, numerous tyrosine kinase inhibitors (TKIs) have been introduced for targeted therapy of various types of malignancies. Due to frequent and increasing use, leading to eventual excretion with body fluids, their residues have been found in hospital and household wastewaters as well as surface water. However, the effects of TKI residues in the environment on aquatic organisms are poorly described. In the present study, we investigated the cytotoxic and genotoxic effects of five selected TKIs, namely erlotinib (ERL), dasatinib (DAS), nilotinib (NIL), regorafenib (REG), and sorafenib (SOR), using the in vitro zebrafish liver cell (ZFL) model. Cytotoxicity was determined using the MTS assay and propidium iodide (PI) live/dead staining by flow cytometry. DAS, SOR, and REG decreased ZFL cell viability dose- and time-dependently, with DAS being the most cytotoxic TKI studied. ERL and NIL did not affect viability at concentrations up to their maximum solubility; however, NIL was the only TKI that significantly decreased the proportion of PI negative cells as determined by the flow cytometry. Cell cycle progression analyses showed that DAS, ERL, REG, and SOR caused the cell cycle arrest of ZFL cells in the G0/G1 phase, with a concomitant decrease of cells in the S-phase fraction. No data could be obtained for NIL due to severe DNA fragmentation. The genotoxic activity of the investigated TKIs was evaluated using comet and cytokinesis block micronucleus (CBMN) assays. The dose-dependent induction of DNA single strand breaks was induced by NIL (≥2 μM), DAS (≥0.006 μM), and REG (≥0.8 μM), with DAS being the most potent. None of the TKIs studied induced micronuclei formation. These results suggest that normal non-target fish liver cells are sensitive to the TKIs studied in a concentration range similar to those previously reported for human cancer cell lines. Although the TKI concentrations that induced adverse effects in exposed ZFL cells are several orders of magnitude higher than those currently expected in the aquatic environment, the observed DNA damage and cell cycle effects suggest that residues of TKIs in the environment may pose a hazard to non-intentionally exposed organisms living in environments contaminated with TKIs.

The cyanobacterial alkaloid cylindrospermopsin (CYN) is being increasingly identified in drinking water supplies worldwide. It is a potent protein synthesis inhibitor and causes human intoxications and animal mortality. The few genotoxicity studies available indicate that CYN is genotoxic, generally implying that it is pro-genotoxic. We evaluated CYN genotoxicity in the human hepatoma cell line, HepG2, analyzing the induction of DNA strand breaks, with the alkaline comet assay, and micronuclei (MNi), nuclear bud (NBUD), and nucleoplasmic bridge (NPB) formation, with the cytokinesis block micronucleus (CBMN) assay. In addition, changes in the expression of genes involved in the response to DNA damage ( P53 , CDKN1A , GADD45α , and MDM2 ) and genes presumably involved in CYN metabolism (genes from the Cytochrome P450 family: CYP1A1 and CYP1A2 ) were determined, using quantitative real-time PCR. Non-cytotoxic concentrations of CYN induced increased DNA damage after 12 and 24 h of exposure and increased the frequency of MNi, NBUDs, and NPBs after 24 h exposure. Moreover, CYN up-regulated the expression of the CYP1A1 and CYP1A2 genes. Although no changes in the expression of the P53 tumor-suppressor gene were found, CYN up-regulated the expression of the P53 downstream-regulated genes CDKN1A , GADD45α , and MDM2 . Our results provide new evidence that CYN is genotoxic and strongly suggest that it needs to be considered in the human health risk assessment.