In this study, data collected from an urban air quality monitoring network are being used for the purpose of evaluating various methodologies used for spatial interpolation in the context of proposing an effective yet simple to apply scheme for PM spatial point estimations. The examined methods are the Inverse Distance Weighting, two linear regression models, the Multiple Linear Regression and the Linear Mixed Model, along with a Feed Forward Neural Network (FFNN) model. These schemes utilize daily PM₁₀ and PM₂.₅ concentrations collected from five and three air quality monitoring sites respectively. In order to obtain the resulted estimations, the leave-one-out cross-validation methodology is used for all methods. The evaluation of their predictive ability is performed by using a combination of difference and correlation statistical measures, scatter plots and statistical tests. The results indicate the usefulness of FFNNs as they are found to be statistically significantly superior for modelling the particulate matter spatial variability. The model performance statistics show that in most cases the error values are considerably lower for the FFNN model. Additionally, the rank and Wilcoxon rank tests reveal that the null hypothesis for equal predictive accuracy is rejected for the majority of monitoring sites and schemes (values lower than the critical t-value). According to the comparison results, the FFNN model is selected for forecasting air quality limit exceedances set by the European Union and World Health Organization air quality standards. For two monitoring sites in which the largest number of exceedances occurred, the probability of detection is high while the probability of false detection is very low, further establishing the neural networks’ predictive ability.

Black carbon (BC) can combine with organic matter and form secondary pollutants known as aged BC. BC and aged BC can cause respiratory system inflammation and induce lesions at relevant sites, but the underlying mechanism has remained unknown. To gain insight into the potential mechanisms, we focused on macrophages and transforming growth factor β-activated kinase 1 (TAK1) which are a crucial factor in inflammation. Our research aims to determine the role of TAK1 in macrophages in pulmonary inflammation induced by particulate matter. In this study, BC and 1,4-naphthoquinone were mixed to model aged BC (1,4NQ-BC) in atmosphere. BC induced mice lung inflammation model, lung macrophage knock-down TAK1 animal model and primary macrophage knock-down TAK1 model were used to explore whether TAK1 in macrophage is a critical role in the process of inflammation. The results showed that the expressions of inflammatory cytokines (IL-1β, IL-6, IL-33) mRNA were significantly increased and the phosphorylation of MAPK and NF-κB signaling pathway related proteins were enhanced in RAW 264.7 cell lines. In vivo studies revealed that the indicators of pulmonary inflammation (pathology, inflammatory cell numbers) and related cytokines (IL-1β, IL-6, IL-33) mRNA expressions in CD11c-Map3k7⁻/⁻ animals were significantly lower than wild-type animals after mice were instilled particles. In mice primary macrophages, the expressions of IL-6, IL-33 mRNA were inhibited after TAK1 gene was knock-down. These results unequivocally demonstrated that TAK1 plays a crucial role in BC induced lung inflammation in mice, and we can infer that BC and 1,4NQ-BC cause these inflammatory responses by stimulating pulmonary macrophages.

Crude oil and its constituents can have adverse effects on ecological and human health when released into the environment. The Canadian Council of Ministers of the Environment (CCME) has developed remedial guidelines and a risk assessment framework for both ecological and human exposure to PHC. One of the assumptions used in the derivation of these guidelines is that plants are unable to take up PHC from contaminated soil and therefore subsequent exposure at higher trophic levels is not a concern. However, various studies suggest that plants are indeed able to take up PHC into their tissues. Consumption of plants is a potential exposure pathway in both ecological (e.g., herbivorous and omnivorous birds, and mammals) and human health risk assessments. If plants can uptake PHC, then the current approach for risk assessment of PHC may underestimate exposures to ecological and human receptors. The present review aims to assess whether or not plants are capable of PHC uptake and accumulation. Twenty-one articles were deemed relevant to the study objective and form the basis of this review. Of the 21 primary research articles, 19 reported detectable PHC and/or its constituents in plant tissues. All but five of the 21 articles were published after the publication of the CCME Canada-Wide Standards. Overall, the present literature review provides some evidence of uptake of PHC and its constituents into plant tissues. Various plant species, including some edible plants, were shown to take up PHC from contaminated soil and aqueous media in both laboratory and field studies. Based on the findings of this review, it is recommended that the soil-plant-wildlife/human pathway should be considered in risk assessments to avoid underestimating exposure and subsequent toxicological risks to humans and wildlife.

Nearshore environments are a critical transitional zone that connects the marine and terrestrial/freshwater ecosystems. The release of anthropogenic chemicals into nearshore ecosystems pose a human and environmental health risk. We investigated the microbial diversity, abundance and function in metal-contaminated sediments collected from the Rongjiang, Hanjiang and Lianjiang River estuaries and adjacent coastal areas using high throughput sequencing. The concentration of nutrients (NO3-N, NO2-N, NH4-N, PO4-P) and metal (Cu, Zn, Cd, Pb, As, Hg) contaminants were higher at the mouth of the rivers compared to the coastal lines, and this was confirmed using cluster analysis. Estimates obtained using geoaccumulation index showed that about 38.9% of the sites were contaminated with Pb and the pollution load index showed that sediment from the mouth of Hanjiang River Estuary was moderately polluted with metals. In the nearshore sediment samples collected, Proteobacteria, Bacteroidetes, Planctomycetes, Chloroflexi, Acidobacteria were the dominant phylum with relative abundances of 46.6%, 8.05%, 6.47%, 5.26%, and 4.59%, respectively. There was no significant correlation between environmental variables and microbial abundance and diversity except for total organic carbon (TOC) (diversity; r = 0.569, p < 0.05) and Cr (diversity; r = 0.581, p < 0.05). At phyla level, Nitrospirae had a significant negative correlation with all metals except Cr, while OD1 had a significant positive correlation with all the metals. Overall, changes in nearshore sediment microbial communities by environmental factors were observed, and these may affect biogeochemical cycling.

Adenosine triphosphate-binding cassette (ABC) transporters, including P-glycoprotein (Pgp) and multi-resistance associated proteins (Mrps), have been considered important participants in the self-protection of zebrafish embryos against environmental pollutants, but their possible involvement in the efflux and detoxification of quantum dots (QDs), as well as their regulation mechanism are currently unclear. In this work, gene expression alterations of ABC transporters, nuclear receptors, and oxidative stress signaling in zebrafish embryos after the treatment of mercaptopropionic acid (MPA)CdTe QDs and MPA-CdSCdTe QDs were investigated. It was observed that both QDs caused concentration-dependent delayed hatching effects and the subsequent induction of transporters like mrp1&2 in zebrafish embryos, indicating the protective role of corresponding proteins against CdTe QDs. Accompanying these alterations, expressions of nuclear receptors including the pregnane X receptor (pxr), aryl hydrocarbon receptor (ahr) 1b, and peroxisome proliferator-activated receptor (ppar)-β were induced by QDs in a concentration- and time-dependent manner. Moreover, elevated oxidative stress, reflected by the reduction of glutathione (GSH) level and superoxide dismutase (SOD) activities, as well as the dramatic induction of nuclear factor E2 related factor (nrf) 2, was also found. More importantly, alterations of pxr and nrf2 were more pronounced than that of mrps, and these receptors exhibited an excellent correlation with delayed hatching rate in the same embryos (R² > 0.8). Results from this analysis demonstrated that the induction of mrp1 and mrp2 could be important components for the detoxification of QDs in zebrafish embryos. These transporters could be modulated by nuclear receptors and oxidative stress signaling. In addition, up-regulation of pxr and nrf2 could be developed as toxic biomarkers of CdTe QDs.

Fluoride is a well-known compound for its usefulness in healing dental caries. Similarly, fluoride is also known for its toxicity to various tissues in animals and humans. It causes skeletal fluorosis leading to osteoporosis of the bones. We hypothesized that when bones are affected by fluoride, the skeletal muscles are also likely to be affected by underlying molecular events involving myogenic differentiation. Murine myoblasts C2C12 were cultured in differentiation media with or without NaF (1 ppm-5 ppm) for four days. The effects of NaF on myoblasts and myotubes when exposed to low (1.5 ppm) and high concentration (5 ppm) were assessed based on the proliferation, alteration in gene expression, ROS production, and production of inflammatory cytokines. Changes based on morphology, multinucleated myotube formation, expression of MyHC1 and signaling pathways were also investigated. Concentrations of NaF tested had no effects on cell viability. NaF at low concentration (1.5 ppm) caused myoblast proliferation and when subjected to myogenic differentiation it induced hypertrophy of the myotubes by activating the IGF-1/AKT pathway. NaF at higher concentration (5 ppm), significantly inhibited myotube formation, increased skeletal muscle catabolism, generated reactive oxygen species (ROS) and inflammatory cytokines (TNF-α and IL-6) in C2C12 cells. NaF also enhanced the production of muscle atrophy-related genes, myostatin, and atrogin-1. The data suggest that NaF at low concentration can be used as muscle enhancing factor (hypertrophy), and at higher concentration, it accelerates skeletal muscle atrophy by activating the ubiquitin-proteosome pathway.

This study investigated the chemical components of fine urban road dust from seven sampling sites, based on which we could predict potential human health effects. The elemental compositions, including the contents of metals and volatile or semivolatile organic compounds, were determined to establish comprehensive chemical profiles of solid road dust. The chemical profiles, consisting of C: H ratio, metal contents, and relative abundances of organic compounds, provided a chemical signature for road dust. To overall cytotoxicity values ranging between 7 and 58%, water extracts contributed less than 15%, and cell death mainly occurred via direct contact with solid-phase components, which possibly indicates that the selected chemical profile of solid-phase road dust components could serve as a strong predictor for BJ and WI-38 cytotoxicity. Pure metal oxides (Cr₂O₃, CuO, Fe₂O₃, MnO₂, NiO, or ZnO) exhibited a positive dose-response, and the corresponding metal contents in solid road dust were well correlated with cell viability. The principal component analysis (PCA) results suggested that the metal contents were stronger predictors of cytotoxicity than the benzene derivative or hydrocarbon contents. The chemical profiles established in this study could be further utilized to identify candidate health hazard factors in road dust.

Low-cost particulate matter (PM) air quality sensors are becoming widely available and are being increasingly deployed in ambient and home/workplace environments due to their low cost, compactness, and ability to provide more highly resolved spatiotemporal PM concentrations. However, the PM data from these sensors are often of questionable quality, and the sensors need to be characterized individually for the environmental conditions under which they will be making measurements. In this study, we designed and assessed a cost-effective (∼$700) calibration chamber capable of continuously providing a uniform PM concentration simultaneously to multiple low-cost PM sensors and robust calibration relationships that are independent of sensor position. The chamber was designed and evaluated with a Computational Fluid Dynamics (CFD) model and a rigorous experimental protocol. We then used this new chamber to calibrate 242 Plantower PMS 3003 sensors from two production lots (Batches I and II) with two aerosol types: ammonium nitrate (for Batches I and II) and alumina oxide (for Batch I). Our CFD models and experiments demonstrated that the chamber is capable of providing uniform PM concentration to 8 PM sensors at once within 6% error and with excellent reliability (intraclass correlation coefficient > 0.771). The study identified two malfunctioning sensors and showed that the remaining sensors had high linear correlations with a DustTrak monitor that was calibrated for each aerosol type (R2 > 0.978). Finally, the results revealed statistically significant differences between the responses of Batches I and II sensors to the same aerosol (P-value<0.001) and the Batch I sensors to the two different aerosol types (P-value<0.001). This chamber design and evaluation protocol can provide a useful tool for those interested in systematic laboratory characterization of low-cost PM sensors.

Toxicity of hazard materials to organism is different between larvae and adult zebrafish. However, this different effect was seldom considered in toxicological modeling. Here, we measured Cd and Pb toxicity for larvae and adult zebrafish (Danio rerio) and assessed whether metal toxicity can be better simulated by the one-compartment or two-compartment toxicokinetic (TK) and toxicodynamic (TD) models with assumption of stochastic death (SD) and individual tolerance (IT), respectively. Results showed that, for larvae, the one-compartment model generally fitted the observed accumulation and survival better than two-compartment model. In contrast, for adult, the two-compartment model simulation satisfied the observed accumulation and survival better than one-compartment model. In addition, both the SD and the IT models generally described the Cd or Pb toxicity well, although the IT model predictions were slightly better than the SD model in adult fish, the opposite phenomenon was observed in larvae. Our results suggested that variations in both TK and TD parameters might be needed to quantify the toxicity sensitivity in larvae and adult zebrafish, and accounting these variations in mechanistic toxicological effect models (e.g. TK-TD) will allow more accurate predictions of hazard materials effects to organisms.

Arsenic (As) present in water is a nonignorable environmental issue, even at low concentrations (≤150 μg L⁻¹). To evaluate the toxic effect of low concentrations of As, zebrafish at early life stage were exposed to 0, 25, 50, 75, or 150 μg L⁻¹ AsIII for 120 h. Our results indicated that low concentration of AsIII decreased zebrafish larvae’s survival rate to 85%, 89% and 86% at 50, 75 and 150 μg L⁻¹. Furthermore, low concentrations of AsIII exposure caused oxidative stress (elevated superoxide dismutase (SOD) activity and influenced the mRNA transcriptional levels of Cu/ZnSOD and MnSOD) and damage (increased malondialdehyde levels). Meanwhile, zebrafish larvae regulated the mRNA transcription of metallothionein and heat shock protein 70 to alleviate toxicity caused by AsIII. These results revealed lower concentrations (≤150 μg L⁻¹) of AsIII had a detriment effect on the survival of fish at early life stage, moreover, oxidative stress caused by AsIII posed potential risk for the zebrafish. This study provides novel insight into low concentration AsIII-induced toxicity in zebrafish.