Importance of Infiltration Rates for Fate and Transport of Benzene in High-Tiered Risk-Based Assessment Considering Korean Site-Specific Factors at Contaminated Sites

Widely used conservative approaches for risk-based assessments of the subsurface transport processes have been calculated using simple analytical equations or general default values. Higher-tier risk assessment of contaminated sites requires the numerical models or additional site-specific values for input parameters. Previous studies have focused on the development of sophisticated models fit into risk-based frameworks. Our study mainly aims to explore the applicability of site-specific parameters and to modify the risk-based fate and transport model according to the types of the site-specific parameters. To apply the modified fate and transport equation and the site-specific default infiltration range, this study assessed the source depletion, leachate concentrations, and exposure concentration of benzene, which is a representative organic contaminant. The numerical models consist of two continuous processes, the fate and transport of contaminants from (1) the soil to the groundwater table in the vadose zone and subsequently (2) from the groundwater table to exposure wells in the saturated zone. Spatially varied Korean domestic recharge data were successfully incorporated into site-specific infiltration parameters in the models. The numerical simulation results were expressed as transient time series of concentrations over time. Results presented the narrow range of predicted concentrations at the groundwater table when site-specific infiltration was applied, and the dilution–attenuation factors for the unsaturated zone (DAFunsat) were derived based on the prediction. When a contaminant travels to the longest path length of 10 m with a source depth of 1 m in the vadoze zone, the simulated DAFunsat ranged from 3 to 4. The highest DAFunsat simulation results are close to 1 when contaminants travel to a source depth of 5 m and the shortest path length of 1 m. In the saturated aquifer below the contaminated sites, the variation in exposure concentration with time at monitoring wells is detected differently depending on the depth of the saturated zone.

Intercomparison of Radiosensitization Induced by Gold and Iron Oxide Nanoparticles in Human Glioblastoma Cells Irradiated by 6 MV Photons

In this work, an intercomparison of sensitization effects produced by gold (GNP) and dextran-coated iron oxide (SPION-DX) nanoparticles in M059J and U87 human glioblastoma cells was performed using 6MV-photons. Three variables were mapped: the nanoparticle material, treatment concentration, and cell radiosensitivity. For U87, GNP treatments resulted in high sensitization enhancement ratios (SER10% up to 2.04). More modest effects were induced by SPION-DX, but still significant reductions in survival were achieved (maximum SER10%=1.61). For the radiosensitive M059J, sensitization by both NPs was poor. SER10% increased with the degree of elemental uptake in the cells, but not necessarily with treatment concentration. For GNP, where exposure concentration and elemental uptake were found to be proportional, SER10% increased linearly with concentration in both cell lines. For SPION-DX, saturation of sensitization enhancement and metal uptake occurred at high exposures. Fold change in the α/β ratios extracted from survival curves are reduced by the presence of SPION-DX but strongly increased by GNPs, suggesting that sensitization by GNPs occurs mainly via promotion of lethal damage, while for SPION-DX repairable damage dominates. The NPs were more effective in eliminating the radioresistant glioblastoma cells, an interesting finding, as resistant cells are key targets to improve treatment outcome.

Accumulation and Release of Mercury in the Lichen Evernia prunastri (L.) Ach

This study investigated the dynamics of the accumulation and release of Hg2+ in lichens, using Evernia prunastri (L.) Ach. as a model species. Thalli were incubated with solutions containing 1, 10, and 100 µM Hg2+ and then exposed for 1, 2, 3, 6, 12, 18, and 24 months at the Botanical Garden of the University of Siena (a location free from local Hg sources). Lichen samples accumulated Hg proportionally to the exposure concentration, and after the exposure, reductions over time were evident, already starting from 1–2 months. After 24 months, samples released 72–74 (healthy thalli) to 94% (unhealthy thalli) of the accumulated Hg, but control values of untreated samples were never reached. Depending on the Hg content after the exposure, stable decreased concentrations were reached after 6–24 months. The results of this study highlight the ability of the lichen E. prunastri to reflect rapidly increasing environmental Hg concentrations, as well as to indicate an ameliorated situation (e.g., the closure of an Hg source). However, we have found evidence that an acute pollution episode can influence the content of Hg in lichens for several years.

Effects of Dimethoate Insecticide on Serum Biochemistry of African Catfish (Clarias gariepinus) Juveniles

The present study was designed to investigate acute toxicity of dimethoate on juvenile Clarias gariepinus. Catfish with mean weight and length of 24.01 ± 11.60 g and 13.98 ± 5.66 cm respectively were exposed to sub-lethal levels of dimethoate in static bioassay system for 28 days and mortality data was statistically evaluated using Finney’s Probit analysis. The 96-hour LC50 value for C. gariepinus was estimated as 29.05 mg/l. The value for the LC50 was used in deducing the sub-lethal concentrations (0.01, 0.15and 0.29 mg/l). Biochemical changes in the serum such as glycogen, total protein, cholesterol, urea and creatinine were analyzed after the exposure period (28 days). The glycogenlevel decreased in all sublethal exposures. An increase in cholesterol at lower exposure concentration, followed by slight increase in urea and creatinine among treated groups was recorded. Behavioural changes which includes changes in skin colour, jerking, restlessness, erratic swimming, among others were observed. Based on the result of this study, it was concluded that C. gariepinus juveniles are very sensitive to low concentration of dimethoate. Dimethoate is highly toxic to juvenile catfishes and as such measures must be taken to avoid its run-off into our aquatic environment thus jeopardizing the recruitment of juvenile catfishes into the fishery.

Mechanisms of Silver Nanoparticle Uptake by Embryonic Zebrafish Cells

Evaluation of the uptake pathways in cells during exposure to nanoparticles (NPs) is key for risk assessment and the development of safer nanomaterials, as the internalisation and fate of NPs is linked to their toxicity and mode of action. Here, we determined the uptake mechanisms activated during the internalisation of 10, 30, and 100 nm AgNPs by embryonic zebrafish cells (ZF4). The uptake results demonstrated an NP size- and time-dependent uptake, showing the highest total silver uptake for the smallest AgNP (10 nm) at the lowest exposure concentration (2.5 μg/mL) after 2 h, while after 24 h, the highest exposure concentration (10 μg/mL) of the 10 nm AgNPs revealed the highest cellular load at 8 pg/cell. Inhibition of the caveolae, clathrin, and macropinocytosis endocytic pathways by pharmaceutical inhibitors (genistein, chlorpromazine, and wortmannin respectively) revealed that uptake was mainly via macropinocytosis for the 10 nm AgNPs and via the caveolae-mediated pathway for the 30 and 100 nm AgNPs. The induction of autophagy was also strongly related to the NP size, showing the highest percentage of induction for the 10 nm (around 3%) compared to naive cells, suggesting that autophagy can be activated along with endocytosis to deal with exposure to NPs. TEM imaging revealed the distribution of NPs across the cytoplasm inside intracellular vesicles. An increase in Early Endosome formation (EE) was observed for the 30 and 100 nm sizes, whereas the 10 nm AgNPs disrupted the activity of EE. The data supports the establishment of adverse outcome pathways by increasing knowledge on the link between a molecular initiating event such as receptor-mediated endocytosis and an adverse outcome, as well as supporting the reduction of animal testing by using alternative testing models, such as fish cell lines.

Air Pollutant Particles, PM2.5, Exposure and Glaucoma in Patients with Diabetes: A National Population-Based Nested Case–Control Study

The global prevalence of diabetes mellitus (DM) has reached 20%. Air pollutants with a particle size of less than 2.5 μm (PM2.5) are a globally recognized risk factor for diabetes and glaucoma. We examined whether the risk of glaucoma would decrease or increase when patients with DM were exposed to different PM2.5 concentrations. Data were obtained from the National Health Insurance Research Database (NHIRD) of Taiwan and the Air Quality Monitoring Network between 2008 and 2013. This nested case–control study involved 197 DM patients with glaucoma and 788 DM patients without glaucoma. Cases and controls were matched (1:4) by gender, age (±5 years), and index date (±6 months), and their data were entered in a logistic regression model adjusted for gender, age, urbanization level, income level, and comorbidities. The odds ratio (OR) of glaucoma at PM2.5 exposure concentration in the fourth quartile (Q4) compared with in the first quartile (Q1) was 1.7 (95% CI: 1.084–2.764). For glaucoma risk, the OR was 1.013 (95% CI: 1.006–1.020) at a PM2.5 exposure concentration in Q1, 1.004 (95% CI: 1.001–1.007) in the third quartile (Q3), and 1.003 (95% CI: 1.001–1.004) in Q4. In the subgroup analysis of patients living in non-emerging towns and non-agricultural towns, the OR for glaucoma in Q4 compared with in Q1 was 2.1 (95% CI: 1.229–3.406) and 1.8 (95% CI: 1.091–2.803), respectively (p trend = 0.001 and 0.011). For patients without migraine, the OR for glaucoma was 1.7 (95% CI: 1.074–2.782; p = 0.006). These results demonstrate that, for patients with DM, PM2.5 increased the risk of glaucoma and PM2.5 was an independent risk factor for glaucoma in patients with DM.

JAK2/STAT3 in role of arsenic-induced cell proliferation: a systematic review and meta-analysis

Objectives Malignant cell proliferation is one of the important mechanisms of arsenic poisoning. A large number of studies have shown that STAT3 plays an important role in cell malignant proliferation, but there are still many contradictions in the effect of arsenic on JAK2/STAT3. This study aims to explore the role of JAK2/STAT3 in arsenic-induced cell proliferation. Methods By taking normal cells as the research object and using Standard Mean Difference (SMD) as the effect size, meta-analysis was used to explore the effect of arsenic on JAK2/STAT3. Then, the dose-effect Meta was used to further clarify the dose-effect relationship of arsenic on JAK2/STAT3. Results Through meta-analysis, this study found that arsenic could promote the phosphorylation of STAT3 (SMD=4.21, 95%CI [1.05, 7.37]), and increase IL-6 and p-JAK2, Vimentin, VEGF expression levels, thereby inducing malignant cell proliferation. In addition, this study also found that arsenic exposure dose (<5 μmol m−3), time(<24 h) and cell type were important sources of heterogeneity in the process of exploring the effects of arsenic on p-STAT3, IL-6 and p-JAK2. Dose-effect relationship meta-analysis results showed that arsenic exposure significantly increased the expression level of IL-6. When the arsenic exposure concentration was less than 7 μmol m−3, the expression level of p-JAK2 upregulated significantly as the arsenic exposure concentration gradually increasing. Moreover, the expression level of p-STAT3 elevated significantly with the gradual increase of the arsenic concentration under 5 μmol m−3 of arsenic exposure, but the expression level of p-STAT3 gradually decreases when the concentration is greater than 5 μmol m−3. Conclusions Exposure to low dose of arsenic could promote the expression of JAK2/STAT3 and induce the malignant proliferation of cells through upregulating IL-6, and there was dose-effect relationship among them.

Short Duration Exposure of 3 µm Polystyrene Microplastics Affected Morphology and Physiology of Watermilfoil (sp. Roraima)

Microplastics are one of the most widely discussed environmental issues worldwide. Several studies have shown the effect of microplastic exposure on the marine environment; however, studies on freshwater systems are lacking. This study was conducted to investigate the effect of microplastics on hydroponically growing emergent freshwater macrophytes, Watermilfoil (sp. Roraima) under controlled environmental conditions. Plants were exposed to 0 mg L− 1 (control), 0.05 mg L− 1, 0.25 mg L− 1, 1.25 mg L− 1, and 6 mg L− 1 of 3 µm polystyrene microspheres for seven days. The oxidative stress, antioxidant response, pigmentations, Fv/Fm, and growth parameters in above-water and below-water parts were analyzed separately. Microscopic observations were performed to confirm the tissue absorbance of the microplastics. Exposure to microplastics altered some parameters; however, growth was not affected. The effect of microplastics was not linear with the exposure concentration for most of the parameters and between 1.25 mg L− 1 and 6 mg L− 1 concentrations. The response trends mostly followed the second-order polynomial distributions. Under the 1.25 mg L− 1 exposure, there were significant changes in root length, H2O2 content, catalase activity, anthocyanin content, and Fv/Fm. There were differences in parameters between the above-water and below-water parts, and the responses of the microplastics followed different trends. Microscopic observations confirmed the attachment of microplastic particles onto newly formed roots, except for older roots or shoot tissues.

Health risk assessment and countermeasure analysis of the elderly population exposed to PM2.5 microenvironment

BACKGROUND: China’s atmospheric PM2.5 pollution is serious, and PM2.5 exerts a negative impact on the human respiratory system, cardiovascular, and mental health, and even more serious health risk for the elderly with weak immunity. OBJECTIVE: This work aims to analyse the impacts of PM2.5 microenvironment exposure on the health of the elderly and provide corresponding countermeasures. METHODS: The survey subjects are 118 retired elderly people in the community. PM2.5 exposure concentrations are monitored in summer (June 10 ∼ July 10, 2019) and winter (November 25 ∼ December 25, 2019). RESULTS: The exposure concentration in winter is higher than that in summer, with statistical difference (P < 0.05). Under the impact of PM2.5 microenvironment exposure, smoking in the elderly can increase the concentration of PM2.5, and long-term exposure to PM2.5 in the elderly can cause mental health problems. CONCLUSION: Long-term exposure of the elderly to the PM2.5 microenvironment leads to physical diseases and even psychological problems, which requires attention.