Latest articles in this journal
Toxics, Volume 11; https://doi.org/10.3390/toxics11020165
During the COVID-19 pandemic, governments in many countries worldwide, including India, imposed several restriction measures, including lockdowns, to prevent the spread of the infection. COVID-19 lockdowns led to a reduction in gaseous and particulate pollutants in ambient air. In the present study, we investigated the substantial changes in selected volatile organic compounds (VOCs) after the outbreak of the coronavirus pandemic and associations with health risk assessments in industrial areas. VOC data from 1 January 2019 to 31 December 2021 were collected from the Central Pollution Control Board (CPCB) website, to identify percentage changes in VOC levels before, during, and after COVID-19. The mean TVOC levels at all monitoring stations were 47.22 ± 30.15, 37.19 ± 37.19, and 32.81 ± 32.81 µg/m3 for 2019, 2020, and 2021, respectively. As a result, the TVOC levels gradually declined in consecutive years due to the pandemic in India. The mean TVOC levels at all monitoring stations declined from 9 to 61% during the pandemic period as compared with the pre-pandemic period. In the current study, the T/B ratio values ranged from 2.16 (PG) to 26.38 (NL), which indicated that the major pollutant contributors were traffic and non-traffic sources during the pre-pandemic period. The present findings indicated that TVOC levels had positive but low correlations with SR, BP, RF, and WD, with correlation coefficients (r) of 0.034, 0.118, 0.012, and 0.007, respectively, whereas negative correlations were observed with AT and WS, with correlation coefficients (r) of −0.168 and −0.150, respectively. The lifetime cancer risk (LCR) value for benzene was reported to be higher in children, followed by females and males, for the pre-pandemic, pandemic, and post-pandemic periods. A nationwide scale-up of this study’s findings might be useful in formulating future air pollution reduction policies associated with a reduction in health risk factors. Furthermore, the present study provides baseline data for future studies on the impacts of anthropogenic activities on the air quality of a region.
Toxics, Volume 11; https://doi.org/10.3390/toxics11020164
Baoji is a medium-sized city in the Guanzhong Plain of northwest China. The compositions of three important organic groups, namely n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and saccharides in atmospheric aerosol with different aerodynamic diameters in power were determined. Both seasonal and daily trends of the target organic chemical groups were demonstrated. The concentration levels of total quantified n-alkanes and saccharides in total suspended particles (TSP) in winter were 541 ± 39 and 651 ± 74 ng·m−3, respectively, much higher than those of the other three seasons. A high total quantified PAHs concentration level of 59.6 ± 6.4 ng·m−3 was also seen in wintertime. n-Alkanes showed a bimodal percent distribution in spring, autumn, and winter. Two peaks were found with the particle sizes of 0.7 μm < Dp < 2.1 μm and 3.3 μm < Dp < 4.7 μm, respectively. In summer, a unimodal was seen with a peak of 4.7 μm < Dp < 5.8 μm. Dehydrated saccharides and PAHs present a unimodal size distribution peaking at the aerodynamic diameters of 0.7 µm < Dp < 2.1 µm. In contrast to glucose and fructose, they mainly exist in the coarse mode particles and have the highest concentrations at aerodynamic diameters of 4.7 µm < Dp < 9.0 µm. The geometric mean diameters (GMD) of n-alkanes and saccharides of the fine particles in winter were higher than in the other seasons. Compared with the data in 2008, the fossil fuel-derived n-alkanes and PAHs in winter decreased by nearly an order of magnitude in 2017. Both the carbon preference index (CPI) of n-alkanes and the diagnostic ratios of PAHs suggest that coal combustion and vehicle exhaust were the major pollution sources of the organic groups in the two decades. It should be noted that the contribution of traffic emissions greatly increased from 2008 to 2017, consistently with a large raise of registered vehicles in Baoji city. The overall results confirm that the control measures conducted by the local government in the recent decade mitigated the air pollution in this city.
Toxics, Volume 11; https://doi.org/10.3390/toxics11020163
Toxicokinetic (TK) models have been used for decades to estimate concentrations of per-and polyfluoroalkyl substances (PFAS) in serum. However, model complexity has varied across studies depending on the application and the state of the science. This scoping effort seeks to systematically map the current landscape of PFAS TK models by categorizing different trends and similarities across model type, PFAS, and use scenario. A literature review using Web of Science and SWIFT-Review was used to identify TK models used for PFAS. The assessment covered publications from 2005–2020. PFOA, the PFAS for which most models were designed, was included in 69 of the 92 papers, followed by PFOS with 60, PFHxS with 22, and PFNA with 15. Only 4 of the 92 papers did not include analysis of PFOA, PFOS, PFNA, or PFHxS. Within the corpus, 50 papers contained a one-compartment model, 17 two-compartment models were found, and 33 used physiologically based pharmacokinetic (PBTK) models. The scoping assessment suggests that scientific interest has centered around two chemicals—PFOA and PFOS—and most analyses use one-compartment models in human exposure scenarios.
Toxics, Volume 11; https://doi.org/10.3390/toxics11020162
Microcystin-LR (MCLR) is an aquatic toxin, which could lead to the development of hepatocellular carcinoma (HCC). Long non-coding RNAs (lncRNAs) are considered important regulatory elements in the occurrence and development of cancer. However, the roles and mechanisms of lncRNAs during the process of HCC, induced by MCLR, remain elusive. Here, we identified a novel lncRNA, namely lnc-GCLC-1 (lncGCLC), which is in close proximity to the chromosome location of glutamate–cysteine ligase catalytic subunit (GCLC). We then investigated the role of lncGCLC in MCLR-induced malignant transformation of WRL68, a human hepatic cell line. During MCLR-induced cell transformation, the expression of lncGCLC and GCLC decreased continuously, accompanied with a consistently high expression of miR-122-5p. Knockdown of lncGCLC promoted cell proliferation, migration and invasion, but reduced cell apoptosis. A xenograft nude mouse model demonstrated that knockdown of lncGCLC promoted tumor growth. Furthermore, knockdown of lncGCLC significantly upregulated miR-122-5p expression, suppressed GCLC expression and GSH levels, and enhanced oxidative DNA damages. More importantly, the expression of lncGCLC in human HCC tissues was significantly downregulated in the high-microcystin exposure group, and positively associated with GCLC level in HCC tissues. Together, these findings suggest that lncGCLC plays an anti-oncogenic role in MCLR-induced malignant transformation, by regulating GCLC expression.
Toxics, Volume 11; https://doi.org/10.3390/toxics11020161
Per- and polyfluoroalkyl substances (PFASs) have received extensive attention due to their various harmful effects. In this study, the adsorptive removal of 10 legacy and emerging PFASs by four anion-exchange resins (including gel and macroreticular resins) were systematically investigated. Our results showed that the capacities of resins absorbing PFASs were ranked in the following order: gel strong base HPR4700 (297~300 μg/g) ≈ macroreticular strong base S6368 (294~300 μg/g) ≈ macroreticular weak base A111S (289~300 μg/g) > gel weak base WA10 (233~297 μg/g). Adsorption kinetic results indicated that the adsorption process might involve chemical and Henry regime adsorption or reaction control. Intraparticle diffusion was probably the major removal step. Co-existing fulvic acid (0.5, 1, 5 mg/L) and inorganic anions (5 mg/L of sulfate, carbonate, bicarbonate) would hinder the PFAS removal by resins with WA10 showing the highest inhibition rate of 17% and 71%, respectively. The adsorption capacities of PFBA decreased from 233 μg/g to 194 μg/g, and from 233 μg/g to 67 μg/g in the presence of fulvic acid and inorganic anions, respectively. PFASs were more easily removed by HPR4700, S6368, and A111S under neutral and alkaline environment. Moreover, WA10 was not able to remove PFASs under an alkaline medium. This study offered theoretical support for removing PFASs from aqueous phases with various resins.
Toxics, Volume 11; https://doi.org/10.3390/toxics11020160
Diquat is a fast, potent, and widely used bipyridine herbicide in agriculture and it induces oxidative stress in several animal models. However, its genotoxic effects on the male reproductive system remain unclear. Melatonin is an effective free-radical scavenger, which has antioxidant and anti-apoptotic properties and can protect the testes against oxidative damage. This study aimed to investigate the therapeutic effects of melatonin on diquat-induced testicular injury in mice. The results showed melatonin treatment alleviated diquat-induced testicular injury, including inhibited spermatogenesis, increased sperm malformations, declined testosterone level and decreased fertility. Specifically, melatonin therapy countered diquat-induced oxidative stress by increasing production of the antioxidant enzymes GPX1 and SOD1. Melatonin treatment also attenuated diquat-induced spermatogonia apoptosis in vivo and in vitro by modulating the expression of apoptosis-related proteins, including P53, Cleaved-Caspase3, and Bax/Bcl2. Moreover, melatonin restored the blood-testicular barrier by promoting the expression of Sertoli cell junction proteins and maintaining the ordered distribution of ZO-1. These findings indicate that melatonin protects the testes against diquat-induced damage by reducing oxidative stress, inhibiting apoptosis, and maintaining the integrity of the blood–testis barrier in mice. This study provides a theoretical basis for further research to protect male reproductive health from agricultural pesticides.
Toxics, Volume 11; https://doi.org/10.3390/toxics11020159
Cisplatin (Cis) is a potent chemotherapeutic agent; however, it is linked with oxidative stress, inflammation, and apoptosis, which may harmfully affect the brain. Hypericum perforatum L. (HP L.) is a strong medicinal plant, but its hydrophobic polyphenolic compounds limit its activity. Therefore, our study aimed to investigate the neuroprotective action of HP L. and its nanoemulsion (NE) against Cis-induced neurotoxicity. The prepared HP.NE was subjected to characterization. The droplet size distribution, surface charge, and morphology were evaluated. In addition, an in vitro dissolution study was conducted. Compared to Cis-intoxicated rats, HP L. and HP.NE-treated rats displayed improved motor activity and spatial working memory. They also showed an increase in their antioxidant defense system and a reduction in the levels of pro-inflammatory cytokines in the brain. Moreover, they showed an increase in the expression levels of the PON-3 and GPX genes, which are associated with a reduction in the brain levels of COX-2 and TP-53. These findings were confirmed by reducing the immunohistochemical expression of nuclear factor kappa (NF-ƘB) and enhanced Ki-67 levels. In conclusion, HP L. is a promising herb and could be used as an adjuvant candidate to ameliorate chemotherapeutic-induced neurotoxicity. Moreover, HP.NE has superior activity in lessening Cis-induced oxidative stress, inflammation, and apoptosis in brain tissue.
Toxics, Volume 11; https://doi.org/10.3390/toxics11020157
Most transcripts from human genomes are non-coding RNAs (ncRNAs) that are not translated into proteins. ncRNAs are divided into long (lncRNAs) and small non-coding RNAs (sncRNAs). LncRNAs regulate their target genes both transcriptionally and post-transcriptionally through interactions with proteins, RNAs, and DNAs. Maternally expressed gene 3 (MEG3), a lncRNA, functions as a tumor suppressor. MEG3 regulates cell proliferation, cell cycle, apoptosis, hypoxia, autophagy, and many other processes involved in tumor development. MEG3 is downregulated in various cancer cell lines and primary human cancers. Heavy metals, such as hexavalent chromium (Cr(VI)), arsenic, nickel, and cadmium, are confirmed human carcinogens. The exposure of cells to these metals causes a variety of cancers. Among them, lung cancer is the one that can be induced by exposure to all of these metals. In vitro studies have demonstrated that the chronic exposure of normal human bronchial epithelial cells (BEAS-2B) to these metals can cause malignant cell transformation. Metal-transformed cells have the capability to cause an increase in cell proliferation, resistance to apoptosis, elevated migration and invasion, and properties of cancer stem-like cells. Studies have revealed that MEG is downregulated in Cr(VI)-transformed cells, nickel-transformed cells, and cadmium (Cd)-transformed cells. The forced expression of MEG3 reduces the migration and invasion of Cr(VI)-transformed cells through the downregulation of the neuronal precursor of developmentally downregulated protein 9 (NEDD9). MEG3 suppresses the malignant cell transformation of nickel-transformed cells. The overexpression of MEG3 decreases Bcl-xL, causing reduced apoptosis resistance in Cd-transformed cells. This paper reviews the current knowledge of lncRNA MEG3 in metal carcinogenesis.
Toxics, Volume 11; https://doi.org/10.3390/toxics11020158
Heavy metal pollution creates environmental health concerns. Among these, iron (Fe), copper (Cu) and manganese (Mn) are commonly found in aquatic environments due to the release of wastewaters. Phytoremediation in hydroponics uses macrophytes to treat contaminated environments, and this is influenced by environmental factors. However, the relationship between these factors and the removal of Fe, Cu and Mn by macrophytes is not known. Therefore, a meta-analysis serves to determine the correlations between environmental factors and the removal of these metals in real wastewater by macrophytes, as well as to identify the role of different aquatic forms of macrophytes in phytoremediation. Emergent macrophytes had higher concentrations of manganese in their tissues, and higher bioconcentrations factor of iron and manganese than floating plants. Regardless of the biotope, higher concentrations of Fe and Cu decreased the ability of plants to bioconcentrate them. The correlations among exposure time, pH, dissolved oxygen, nitrogen, phosphorus, photoperiod and metal phytoremediation by plants were also found. It can be concluded that the emergent macrophytes showed better performance in terms of the removal of Fe, Cu and Mn, and that the significant correlations between environmental factors and removal vary with the type of metal and the environmental factor analyzed.
Toxics, Volume 11; https://doi.org/10.3390/toxics11020156
According to European regulations, migration from food packaging must be safe. However, currently, there is no consensus on how to evaluate its safety, especially for non-intentionally added substances (NIAS). The intensive and laborious approach, involving identification and then quantification of all migrating substances followed by a toxicological evaluation, is not practical or feasible. In alignment with the International Life Sciences Institute (ILSI) and the European Union (EU) guidelines on packaging materials, efforts are focused on combining data from analytics, bioassays and in silico toxicology approaches for the risk assessment of packaging materials. Advancement of non-targeted screening approaches using both analytical methods and in vitro bioassays is key. A protocol was developed for the chemical and biological screening of migrants from coated metal packaging materials. This protocol includes guidance on sample preparation, migrant simulation, chemical analysis using liquid chromatography (LC-MS) and validated bioassays covering endocrine activity, genotoxicity and metabolism-related targets. An inter-laboratory study was set-up to evaluate the consistency in biological activity and analytical results generated between three independent laboratories applying the developed protocol and guidance. Coated packaging metal panels were used in this case study. In general, the inter-laboratory chemical analysis and bioassay results displayed acceptable consistency between laboratories, but technical differences led to different data interpretations (e.g., cytotoxicity, cell passages, chemical analysis). The study observations with the greatest impact on the quality of the data and ultimately resulting in discrepancies in the results are given and suggestions for improvement of the protocol are made (e.g., sample preparation, chemical analysis approaches). Finally, there was agreement on the need for an aligned protocol to be utilized by qualified laboratories for chemical and biological analyses, following best practices and guidance for packaging safety assessment of intentionally added substances (IAS) and NIAS to avoid inconsistency in data and the final interpretation.