We have developed a virtual screening procedure to identify potential ligands to the aryl hydrocarbon receptor (AhR) among a set of industrial chemicals. AhR is a key target for dioxin-like compounds, which is related to these compounds’ potential to induce cancer and a wide range of endocrine and immune system-related effects. The virtual screening procedure included an initial filtration aiming at identifying chemicals with structural similarities to 66 known AhR binders, followed by 3 enrichment methods run in parallel. These include two ligand-based methods (structural fingerprints and nearest neighbor analysis) and one structure-based method using an AhR homology model. A set of 6445 commonly used industrial chemicals was processed, and each step identified unique potential ligands. Seven compounds were identified by all three enrichment methods, and these compounds included known activators and suppressors of AhR. Only approximately 0.7% (41 compounds) of the studied industrial compounds was identified as potential AhR ligands and among these, 28 compounds have to our knowledge not been tested for AhR-mediated effects or have been screened with low purity. We suggest assessment of AhR-related activities of these compounds and in particular 2-chlorotrityl chloride, 3-p-hydroxyanilino-carbazole, and 3-(2-chloro-4-nitrophenyl)-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2(3H)-one.

Few studies regarding the health effects of long-term exposure to particulate matter with an aerodynamic diameter of 2.5 μm or less (PM₂.₅) have been carried out in Asia or the Middle East. The objective of our study was to assess total, lung cancer and chronic obstructive pulmonary disease (COPD) mortality attributed to long-term exposure to PM₂.₅ among adults aged over 30 years in Tehran from March 2013 to March 2016 using AirQ⁺ software. AirQ⁺ modeling software was used to estimate the number of deaths attributed to PM₂.₅ concentrations higher than 10 μg m⁻³. Air quality data were obtained from the Department of Environment (DOE) and Tehran Air Quality Control Company (TAQCC). Only valid stations with data completeness of 75% in all 3 years were selected for entry into the model. The 3-year average of the 24-h concentrations was 39.17 μg m⁻³. The results showed that the annual average concentration of PM₂.₅ in 2015–2016 was reduced by 13% compared to that in 2013–2014. The annual average number of all natural, COPD, and lung cancer deaths attributable to long-term exposure to PM₂.₅ in adults aged more than 30 years was 5073, 158, and 142 cases, respectively. The results of all three health endpoints indicate that the mortality attributable to PM₂.₅ decreased yearly from 2013 to 2016 and that the reduced mortality was related to a corresponding reduction in the PM₂.₅ concentration. Considering these first positive results, the steps that have been currently taken for reducing air pollution in Tehran should be continued to further improve the already positive effects of these measures on reducing health outcomes.

In this study, the effect of Fe³⁺, Fe²⁺, and Mn²⁺ dose, solution pH, reaction temperature, background water matrix (i.e., inorganic anions, cations, and natural organic matters (NOM)), and the kinetics and mechanism for the reaction system of Fe(VI)/Fe³⁺, Fe(VI)/Fe²⁺, and Fe(VI)/Mn²⁺ were investigated systematically. Traces of Fe³⁺, Fe²⁺, and Mn²⁺ promoted the DCF removal by Fe(VI) significantly. The pseudo-first-order rate constant (kₒbₛ) of DCF increased with decreasing pH (9–6) and increasing temperature (10–30 °C) due to the gradually reduced stability and enhanced reactivity of Fe(VI). Cu²⁺ and Zn²⁺ ions evidently improved the DCF removal, while CO₃²⁻ restrained it. Besides, SO₄²⁻, Cl⁻, NO₃⁻, Mg²⁺, and Ca²⁺ almost had no influence on the degradation of DCF by Fe(VI)/Fe³⁺, Fe(VI)/Fe²⁺, and Fe(VI)/Mn²⁺ within the tested concentration. The addition of 5 or 20 mg L⁻¹ NOM decreased the removal efficiency of DCF. Moreover, Fe₂O₃ and Fe(OH)₃, the by-products of Fe(VI), slightly inhibited the DCF removal, while α-FeOOH, another by-product of Fe(VI), showed no influence at pH 7. In addition, MnO₂ and MnO₄⁻, the by-products of Mn²⁺, enhanced the DCF degradation due to catalysis and superposition of oxidation capacity, respectively. This study indicates that Fe³⁺ and Fe²⁺ promoted the DCF removal mainly via the self-catalysis for Fe(VI), and meanwhile, the catalysis of Mn²⁺ and the effect of its by-products (i.e., MnO₂ and MnO₄⁻) contributed synchronously for DCF degradation. Graphical abstract ᅟ

The extensive use of plasticizers containing di-n-butyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP) results in high residual concentrations in agricultural soils and poses potential risks to human health through the food chain. Here, two rice cultivars with low (Fengyousimiao) and high (Peizataifeng) phthalic acid ester (PAE) accumulation were grown in leaching columns packed with DBP- and DEHP-contaminated soils to investigate their transport, fraction distribution, and accumulation in soil-rice-water system. Significant differences in soil vertical distribution of DBP and DEHP were observed among the two cultivars, sterilization and non-sterilization treatments. Both DBP and DEHP could leach to the bottom layer even though their concentrations in both soil and pore water decreased along with soil depth. DBP and DEHP concentrations in pore water were significantly correlated with those in corresponding soil layer at ripening stage. The available fractions including desorbing and non-desorbing fractions were predominant in the total concentrations of DBP and DEHP of soils. DBP and DEHP storages in coarse soil fractions (i.e., coarse and fine sands) with higher bioavailability displayed higher bioconcentration factors compared to finer soil fractions (i.e., silt and clay), and bioconcentration factors of Peizataifeng were higher than those of Fengyousimiao. The variations in vertical migration and accumulation of DBP and DEHP by the two cultivars implied different adverse effects on the security of groundwater and food.

Phthalates are a group of chemical compounds used as plasticizers in the manufacture of plastic materials. They can be present in many commonly used products. There seems to be a relationship between exposure to phthalates and the occurrence of metabolic dysfunctions, such as a decrease in glucose tolerance, oxidative stress, loss of beta cells, and a decrease in insulin synthesis. As beta cells play a key role in the onset of type 1 diabetes mellitus (T1DM), we sought to investigate the relationship between exposure to phthalates and the diagnosis of T1DM in prepubertal children. Design concentrations of phthalate metabolites were compared in the urine of a population of prepubertal children with new-onset diabetes, patients with T1DM diagnosed more than 6 months previously, and healthy control children. Although the concentrations of DBP and DiBP metabolites were statistically identical in the new-onset diabetes, diabetes, and control groups, there was a clear trend for higher levels of DiBP metabolites in the children with new-onset diabetes. In our sample, there was a trend for higher levels of DiBP metabolites in children with new-onset diabetes.

Natural areas are quickly degraded by opening new settlement and industrial areas in order to meet the increasing demand of the growing population. Concreting, modification of land surfaces, complex urban structures, and depressed urban environments contribute to the formation of an Urban Heat Island (UHI). In this study, the outdoor measurements, meteorological parameters related to the thermal indices such as humidity, temperature, wind velocity, and direction for 24 h measurements, were evaluated. The ENVI-met micro-scale model was performed for evaluating alternative scenarios for winter and summer on thermal comfort for better urban environments. Meteorological parameters together with vegetation characteristics were analyzed for making possible scenarios in botanical garden, auto industrial area, city center, and rural open area. The average of the vegetated simulations of the botanical garden was about 2.2 °C cooler than this of the mean of current situation in the city center. Based upon the average of all stations, it was determined that the temperature increased 1.4 °C with the simulation of both wooded areas in winter. However, the mean temperature of all stations with coniferous plants was 1.2 °C cooler, in summer. It was concluded that deciduous plants in city center produced more positive results than coniferous plants in winter. In general, it can be said that afforestation in cold climatic regions provides great advantages for both summer and winter and positively affects outdoor thermal comfort. However, it needs further measurement and further research in this regard.

Column leaching studies have been suggested as a reference for site-specific prediction of the long-term leaching characteristics of trace constituents in granular materials used as construction materials. In this study, the concept of the long-term leaching prediction using column studies is applied for dredged marine sediment impacted by heavy metals. The column studies show tailing of the liquid to solid ratio-dependent heavy metal leaching for sediment after heavy metal treatment by acid washing. A dual-mode first-order decay model, applied for the first time in this study for column leaching studies, is able to reproduce the leaching characteristics observed. A procedure for long-term leaching prediction using the dual-mode model is developed and applied to a virtual field scenario for which the sediment is beneficially used as a construction material. The prediction results show that by more accurately reproducing the column study results, the dual-mode model generally predicts greater long-term heavy metal loading to the underlying soil layer and longer duration of leaching than the single-mode model. The heavy metal leaching observed in the columns does not show any correlation with the sequential extraction procedure and toxicity characteristic leaching procedure (TCLP) results, suggesting that the column leaching test should be considered to be independent of such batch test procedures.

Spirulina platensis (SP) is a traditionally used microalga for a wide range of pharmacological activities, including amelioration of heavy metals and pesticides toxicity. This study evaluated the antioxidant and organoprotective effects of SP against diazinon (DZN)-induced subacute toxicity on the blood, heart, liver, and kidneys of male Wistar albino rats. Diazinon (20 mg/kg, subcutaneous) was administered to animals either alone or along with an oral pure SP powder at doses of 500 and 1000 mg/kg. Alterations in hematological and serum biochemical parameters, as well as oxidative stress markers in the hepatic, renal, and cardiac tissues were evaluated, using colorimetric spectrophotometric techniques. The obtained results revealed that in comparison to the control group, DZN-treated rats exhibited significantly lower (p < 0.05) red blood cells and platelets counts, hemoglobin and hematocrit values, and activities of serum acetylcholinesterase and tissue antioxidant enzymes (glutathione peroxidase, superoxide dismutase, and catalase). Meanwhile, biochemical analysis showed significantly higher (p < 0.05) white blood cells count, serum concentrations of tumor necrosis factor-α and cardiac [creatine kinase (CK) and CK-muscle/brain fraction], hepatic [transaminases and alkaline phosphatase], and renal [uric acid, urea and creatinine] injury markers, and tissue levels of malondialdehyde (a marker of lipid peroxidation) in the DZN-intoxicated group, compared to normal controls. Interestingly, the administration of SP significantly ameliorated the previous hemato-biochemical alterations and mitigated DZN-induced organ injuries and oxidative stress. In conclusion, the natural antioxidant microalga (SP) effectively alleviated the DZN-induced hematologic alterations and organ injuries, probably through its antioxidant and anti-inflammatory activities.

Silicon is widely available in soil and is known to mitigate both biotic and abiotic stress in plants. Very low doses of silicon are becoming increasingly essential in rice for biofortification and preventing water loss. Soil salinity is a matter of grave concern in various parts of the world, and silicon is a suitable candidate to mitigate salinity-induced stress of important plants in affected areas. The present study investigates the protective capability of exogenously applied silicon in ameliorating NaCl-induced toxicity in two rice (Oryza sativa L.) cultivars, the salt-sensitive MTU 1010, and salt-tolerant Nonabokra. Rice seedlings were treated with three doses of NaCl (25, 50, and 100 mM), initially alone and subsequently in combination with 2 mM sodium silicate (Na₂SiO₃, 9H₂O). After 21 days, these plants were examined to determine levels of reduced glutathione, ascorbic acid, cysteine, and activities of different enzymes involved in the ascorbate-glutathione cycle, viz., glutathione reductase (GR), ascorbate peroxidase (APX), glutathione peroxidase (GPx), and glutathione S-transferase (GST). Though ROS levels increased in both the cultivars with increasing NaCl concentrations, cv. MTU 1010 accumulated comparatively higher amounts. A differential response of NaCl-induced toxicity on the two cultivars was observed with respect to the various enzymatic and non-enzymatic antioxidants. APX and GST activities, as well as, cysteine contents, increased concomitantly with salt concentrations, whereas GR activity declined at increasing salt concentrations, in both cultivars. Activity of GPx increased in cv. Nonabokra but declined in cv. MTU 1010, under similar NaCl concentrations. Reduced glutathione (GSH) contents decreased in both cultivars, whereas ascorbate contents declined in only the sensitive cultivar. Application of silicon, along with NaCl, in the test seedlings of both the cultivars, reduced ROS accumulation and boosted antioxidant defense mechanism, through enhancing ascorbate and GSH levels, and activities of ascorbate-glutathione cycle enzymes as well. However, amelioration of salt-induced damages in the sensitive cv. MTU 1010 was more pronounced upon silicon administration, than the tolerant cv. Nonabokra. Thus, cv. MTU 1010 was found to be more responsive to applied silicon. Hence, this study was instrumental in realizing a successful strategy in silicon-mediated amelioration of salinity stress in plants.

It is well known that alkaline amendments could effectively decrease the bioavailability of heavy metals in soils. However, the vertical distribution of heavy metals and the nutrients enriching in amendments are little concerned during long-term field remediation. Thus, the objective of the present study was to investigate the vertical distribution and availability of Cu, Cd, Ca, and P after a 7-year field experiment. In this study, a single application of lime and apatite was conducted with the rates of 1.71–6.84 and 6.84–19.8 tons/ha, respectively. Soil pH and immobilization efficiency of Cu and Cd were both increased with increasing dosages of lime and apatite (0–50 cm). Applications of lime and apatite decreased the mobility of Cu and Cd although soil Cu and Cd in the surface soil were increased due to the input by atmospheric dry and wet deposition. Moreover, concentrations of Cu and Cd in lime- and apatite-amended soils (0–13 cm) were higher than those in the control group. However, applications of lime and apatite decreased the downward eluviations of heavy metals in soils (13–50 cm). For soil nutrients, the Ca concentrations at 0–13 and 13–30 cm were both enhanced with increasing amendment dosages, while only soil P concentration at 0–13 cm was increased in apatite-treated soils and majority of them presented in stable-P. In addition, resin-P was increased with increasing dosages of the apatite, which suggested that high eutrophication risk was induced by excessive P loss. Thus, more attention should be paid to the nutrients (phosphorus) and pollutants enriching in the amendments during in-situ remediation of heavy metal-contaminated soils.