Potentially toxic elements (PTEs) pollution is the fastest growing concern around the entire globe especially in developing countries. Rapid industrialization and urbanization are the dominant sources of anthropogenic soil-food chain contamination with PTEs. The intent of current study was to investigate the interactive levels of Cu, Fe, Mn, Ni, Pb, and Zn in soil and their accumulation in wheat (Triticum aestivum L.) samples collected from 96 sites including industrial, urban, and peri-urban areas of a leading multi-industrialized center (Faisalabad) of Pakistan. According to results obtained from present study, non-carcinogenic (HQ) and life-time carcinogenic risks (CR) of the PTEs to the local inhabitants were estimated following the risk assessment modals proposed by the US-EPA. With respect to estimated HQ for chronic non-carcinogenic risk of Mn, Ni, and Pb, higher potential hazards were observed as compared to Cu, Fe, and Zn. Meanwhile, the carcinogenic risk of Ni marginally exceeded the limit described by US-EPA for adults. Overall, the health risks of PTEs with the consumption of wheat were lower than the limits described by US-EPA except for Ni. However, continuous consumption of this PTEs contaminated food may result the potential buildup of poisonousness and various disorders in humans. Therefore, long-term monitoring and gastrointestinal bio-accessibility studies are requisite for the safety of humans under such conditions.

Nanoscale zero-valent iron particles (NZVIs) confined in the mesochannels of SBA-15 have superabilities in the remediation of contaminated groundwater. As a new kind of remediation nanomaterials, it is necessary to investigate the ecotoxicity of NZVIs/SBA-15 composites during their applications. In this study, we evaluated the toxicity of NZVIs/SBA-15 on Escherichia coli and proposed a possible mechanism. Compared with the bare NZVIs and SBA-15 surface-supported NZVIs at the same equivalent concentration of NZVIs (0.42 or 0.84 g/L), NZVIs/SBA-15 composites had a minimal cytotoxicity on E. coli, though they had the smallest iron nanoparticle size, the largest zeta potential, and the best stability in water. The mechanism may be attributed to the protection of the mesochannels and the electrostatic hindrance resulting from the silica host that could keep NZVIs from directly contacting with the cell. Thus, NZVIs confined in the mesostructures can be safely used in the remediation of contaminated natural water.

PTFE is used as an inner coating material in non-stick cookware. This unique polymer coating prevents food from sticking in the pans during the cooking process. Such cookware is also easy to wash. At normal cooking temperatures, PTFE-coated cookware releases various gases and chemicals that present mild to severe toxicity. Only few studies describe the toxicity of PTFE but without solid conclusions. The toxicity and fate of ingested PTFE coatings are also not understood. Moreover, the emerging, persistent, and well-known toxic environmental pollutant PFOA is also used in the synthesis of PTFA. There are some reports where PFOA was detected in the gas phase released from the cooking utensils under normal cooking temperatures. Due to toxicity concerns, PFOA has been replaced with other chemicals such as GenX, but these new alternatives are also suspected to have similar toxicity. Therefore, more extensive and systematic research efforts are required to respond the prevailing dogma about human exposure and toxic effects to PTFE, PFOA, and GenX and other alternatives.

Plant–microbe interactions are considered to be important processes determining the efficiency of phytoremediation of heavy metal-contaminated soils. However, relatively little is known about how these interactions are influenced by chromium (Cr) contamination. The effect of Cr stress on metal uptake, root organic acid composition, and rhizosphere bacterial communities was studied using two genotypes of the metallophyte Silene vulgaris, which have shown different tolerance to Cr(VI). The results indicated that root biomass and shoot biomass were not significantly influenced by Cr treatment, but metal uptake in shoots and roots was significantly impacted by the genotype. Principal component analyses (PCA) showed that variation in organic acids oxalic, citric, malic, formic, lactic, acetic, and succinic differed between genotypes. Changes in root organic acid contents in response to Cr revealed a significant increase of oxalic acid in genotype SV-21. The denaturing gradient gel electrophoresis (DGGE) cluster analysis showed that the community structure (determined by PCR-DGGE) was affected by plant genotype and, to a lesser extent, by Cr contamination, the first being the most influential factor shaping the rhizosphere microbiome. Under Cr pollution, a shift in the relative abundance of specific taxa was found and dominant phylotypes were identified as Variovorax in SV-21 and Chitinophaga niastensis, Pontibacter sp., and Ramlibacter sp. in SV-38. These results provided the basis for further studies aimed at the combined use of plants and soil microorganisms in the remediation of Cr-polluted soils.

Sediment tends to accumulate inorganic and persistent hydrophobic organic contaminants representing one of the main sinks and sources of pollution. Generally, contaminated sediment poses medium- and long-term risks to humans and ecosystem health; dredging activities or natural resuspension phenomena (i.e., strongly adverse weather conditions) can remobilize pollution releasing it into the water column. Thus, ex situ traditional remediation activities (i.e., dredging) can be hazardous compared to in situ techniques that try to keep to a minimum sediment mobilization, unless dredging is compulsory to reach a desired bathymetric level. We reviewed in situ physico-chemical (i.e., active mixing and thin capping, solidification/stabilization, chemical oxidation, dechlorination, electrokinetic separation, and sediment flushing) and bio-assisted treatments, including hybrid solutions (i.e., nanocomposite reactive capping, bioreactive capping, microbial electrochemical technologies). We found that significant gaps still remain into the knowledge about the application of in situ contaminated sediment remediation techniques from the technical and the practical viewpoint. Only activated carbon-based technologies are well developed and currently applied with several available case studies. The environmental implication of in situ remediation technologies was only shortly investigated on a long-term basis after its application, so it is not clear how they can really perform.

Toxic chemicals entered into human body would undergo a series of metabolism, transport and excretion, and the key roles played in there processes were metabolizing enzymes, which was regulated by the pregnane X receptor (PXR). However, some chemicals in environment could activate or antagonize human pregnane X receptor, thereby leading to a disturbance of normal physiological systems. In this study, based on a larger number of 2724 structurally diverse chemicals, we developed qualitative classification models by the k-nearest neighbor method. Moreover, the logarithm of 20 and 50% effective concentrations (log EC ₂₀ and log EC ₅₀) was used to establish quantitative structure-activity relationship (QSAR) models. With the classification model, two descriptors were enough to establish acceptable models, with the sensitivity, specificity, and accuracy being larger than 0.7, highlighting a high classification performance of the models. With two QSAR models, the statistics parameters with the correlation coefficient (R ²) of 0.702–0.749 and the cross-validation and external validation coefficient (Q ²) of 0.643–0.712, this indicated that the models complied with the criteria proposed in previous studies, i.e., R ² > 0.6, Q ² > 0.5. The small root mean square error (RMSE) of 0.254–0.414 and the good consistency between observed and predicted values proved satisfactory goodness of fit, robustness, and predictive ability of the developed QSAR models. Additionally, the applicability domains were characterized by the Euclidean distance-based approach and Williams plot, and results indicated that the current models had a wide applicability domain, which especially included a few classes of environmental contaminant, those that were not included in the previous models.

Polyhalogenated N-methylpyrroles (PMPs) are halogenated natural products (HNPs) recently detected in seagrass, blue mussels, and other marine organisms. In this study, we synthesized 2,3,4,5-tetrachloro-N-methylpyrrole (Cl₄-MP), 2,3,4,5-tetrabrominated-N-methylpyrrole (Br₄-MP, aka TBMP), and mixed tetrahalogenated (Cl and Br) N-methylpyrrole congeners. Use of one- and two-dimensional ¹H and ¹³C NMR verified the structures of isolated/enriched 3,4-dibromo-2,5-dichloro-N-methylpyrrole (3,4-Br₂-2,5-Cl₂-MP), 2,3,4-tribromo-5-chloro-N-methylpyrrole (2,3,4-Br₃-5-Cl-MP), and 3-bromo-2,4,5-trichloro-N-methylpyrrole (3-Br-2,4,5-Cl₃-MP). GC/EI-MS and GC/ECNI-MS mass spectra of the five PMPs were studied with regard to fragmentation pattern and individual responses which were strongly affected by the presence (or absence) of Br in α-position(s). Quantitative solutions of the synthesized standards were used to determine the elution order of isomers and to quantify PMPs in selected blue mussel samples (Mytilus sp.) from the European Atlantic coast (Spain, France), the North Sea (the Netherlands, Germany) and Baltic Sea (Germany). PMPs were detected in all samples and the concentrations ranged between 0.6 and 52 μg/kg lipids with Br₄-MP being the most abundant representative of this substance class.

Sulfate contamination is an increasingly serious environmental problem related to microbial reduction processes in anoxic paddy soil. This study revealed the changes and interrelations of ferric iron [Fe(III)] reduction, ferrous iron [Fe(II)] oxidation, and oxygenic photosynthesis in an anoxic paddy soil (Fe-accumuli-Stagnic Anthrosols) amended with a range of high sulfate concentrations. Soil slurries mixed with 0 (control), 50, 100, 200, and 400 mmol kg⁻¹ Na₂SO₄ were incubated anaerobically under dark and light conditions. The changes in chlorophyll a (Chl a), Fe(II), pH levels, and the chlorophyll absorption spectrum were determined over a 42-day period. Fe(II) concentrations increased with the addition of sulfate under dark conditions, while Fe(III) reduction potential was enhanced by increasing sulfate addition. The effect of light on Fe(II) concentration was observed after 16 days of incubation, when Fe(II) started to decrease markedly in the control. The decrease in Fe(II) slowed with increasing sulfate addition. The concentrations of Chl a increased in all treatments after 16 days of incubation under light conditions. There was a reduction in Chl a accumulation with increasing sulfate at the same incubation time. The absorption peaks of chlorophyll remained shorter than the 700-nm wavelength throughout the incubation period. The pH of all treatments decreased in the first week and then increased thereafter. The pH increased with sulfate addition and light conditions. In conclusion, contamination with high concentrations of sulfate could accelerate Fe(III) reduction while inhibiting oxygenic photosynthesis, which correspondingly slows chemical Fe(II) oxidation in an anoxic paddy soil.

Arsenic and chromium are widespread environmental contaminants that affect global health due to their toxicity and carcinogenicity. To date, few studies have investigated exposure to arsenic and chromium in a population residing in a high-risk environmental area. The aim of this study is to evaluate the exposure to arsenic and chromium in the general population with no occupational exposure to these metals, resident in the industrial area of Taranto, Southern Italy, through biological monitoring techniques. We measured the levels of chromium, inorganic arsenic, and methylated metabolites, in the urine samples of 279 subjects residing in Taranto and neighboring areas. Qualified health staff administered a standardized structured questionnaire investigating lifestyle habits and controlling for confounding factors. The biological monitoring data showed high urinary concentrations of both the heavy metals investigated, particularly Cr. On this basis, it will be necessary to carry out an organized environmental monitoring program, taking into consideration all exposure routes so as to correlate the environmental concentrations of these metals with the biomonitoring results.