A review of global outlook on fluoride contamination in groundwater with prominence on the Pakistan current situation

Several million people are exposed to fluoride (F^?) via drinking water in the world. Current review emphasized the elevated level of fluoride concentrations in the groundwater and associated potential health risk globally with a special focus on Pakistan. Millions of people are deeply dependent on groundwater from different countries of the world encompassing with an elevated level of fluoride. The latest estimates suggest that around 200 million people, from among 25 nations the world over, are under the dreadful fate of fluorosis. India and China, the two most populous countries of the world, are the worst affected. In Pakistan, fluoride data of 29 major cities are reviewed and 34% of the cities show fluoride levels with a mean value greater than 1.5 mg/L where Lahore, Quetta and Tehsil Mailsi are having the maximum values of 23.60, 24.48, > 5.5 mg/L, respectively. In recent years, however, other countries have minimized, even eliminated its use due to health issues. High concentration of fluoride for extended time period causes adverse effects of health such as skin lesions, discoloration, cardiovascular disorders, dental fluorosis and crippling skeletal fluorosis. This review deliberates comprehensive strategy of drinking water quality in the global scenario of fluoride contamination, especially in Pakistan with prominence on major pollutants, mitigation technologies, sources of pollution and ensuing health problems. Considering these verities, health authorities urgently need to establish alternative means of water decontamination in order to prevent associated health problems.     

Development of the “rare-earth” hypothesis to explain the reasons of geophagy in Teletskoye Lake are kudurs (Gorny Altai,Russia)

The mineral and chemical composition of the liquid and lithogenous substances, consumed by the wild ungulate animals, at the kudurs of the Teletskoye Lake, Gorny Altai, Russia, was studied. It was investigated that all examined kudurits are argillous-aleurolitic and get in the interval from 1 to 100 μm with the predominance of the fraction 10 μm. By the mineral composition, the lithogenous kudurits present the quartz-feldspathic-hydromicaceous-chloritic mineral formations with the large content of the quartz particles (20–43%) and sodium-containing plagioclases (albite, 15–32 wt%). The lithogenous kudurits are the products of the reconstitution of the metamorphic cleaving stones as a result of the glacier abrasive effect, subsequent its aqueous deposits and then eolation in the subaerial conditions. The fontinal waters consumed at the kudurs are subsaline chloride-hydrocarbonate-sodium and sulphated-hydrocarbonate-calcium types. It essentially differs by the increased content of rare-earth elements in reference to the lake water. The acid (HCl, pH-1) extracts from the kudurits more actively extract calcium (10–35% of the gross contents; sodium extracts at the level of 1–3%). The most fluent in the microelements composition are Cu, Be, Sr, Co, Cd, Pb, Sc, Y and rare-earth elements. The transit of all these elements into the dissoluted form fluctuates about 10% from the gross contents. The reason of geophagy is related to tendency of herbivores to absorb mineralized subsoils enriched by the biologically accessible forms of rare-earth elements, arisen as a result of vital activity of specific microflora.     

Hydrogeochemical and biomedical insights into germanium potential of curative waters: a case study of health resorts in the Sudetes Mountains (Poland)

Germanium is considered to be a non-essential element; however, little is still known about its significance for living organisms. It exerts prophylactic and therapeutic effects in the treatment of serious diseases such as cancer, HIV infection, and others. Germanium does not exhibit acute toxicity, but, as it tends to accumulate in various organs and tissues, undesirable and even dangerous side effects have been reported after prolonged and/or high dosage application. In general, inorganic compounds of germanium are more toxic than its organic compounds. Further studies should be performed to elucidate the exact molecular mechanism of germanium action, to determine the safe and effective dose of germanium via curative/mineral waters, and to understand the applications and benefits of using germanium-enriched waters in balneotherapy. The geochemistry of curative (cold CO₂-rich, thermal) waters from spas in the Sudetes (Poland) was clarified in terms of components and mineral phases which might govern germanium. Germanium and silicon in thermal (above 20 °C) waters presumably result from the solubility of silicates in crystalline (granites, gneisses) aquifer rocks and might be controlled by neo-formed quartz. The cold CO₂-rich waters revealed a significant diversity of aqueous chemistry and relationships of germanium with iron, silicon, or arsenic. Locally, both in sedimentary (sandstones) and metamorphic (gneisses) aquifer rocks, primary (silicates) and/or secondary (oxides) iron-containing minerals likely release germanium into solution. In the CO₂-rich waters of the western part of the K?odzko Region, germanium distinctly correlates with arsenic. It is hypothesized that both elements are co-sourced from crystalline basement and/or migration of substances of post-magmatic origin along deep-seated dislocations related to the seismically active Po?í?í-Hronov fault zone. This area was proposed as the most prospective one for finding waters rich in germanium in the Sudetes.     

Geochemical caper fingerprints as a tool for geographical origin identification

The identification of geographical origin of food products is important for both consumers and producers to ensure quality and avoid label falsifications. The caper plant (Capparis spinosa L., Brassicales Capparidaceae), a xerophytic shrub common in the Mediterranean area, produces buds and fruits that are commercialized in brine at high price. Those grown in Italy in the Aeolian Islands are renowned for their high quality. This study is aimed to establish a correlation between the geological and geochemical features of soil and the chemical composition of caper buds grown in two Aeolian Islands, Lipari and Salina. Major and trace elements were investigated by X-ray fluorescence and inductively coupled plasma-mass spectrometry in soil and caper samples from three localities in Lipari and Salina, and data from the three sites were compared by a nonparametric test, a correlation test and multivariate statistics (principal component analysis). The results allowed to discriminate soils according to geolithological characteristics of each area and detect a statistically significant correspondence between soil and caper samples for the elements Co, Fe, Mg and Rb, identifying thus possible geochemical caper fingerprints of origin. These results may also be useful to protect the high quality of Aeolian caper products by a suitable “Made in Italy” trademark and avoid falsifications and frauds.     

Geochemistry and quality of groundwater of the Yarmouk basin aquifer,north Jordan

Quality of groundwater in the Yarmouk basin, Jordan has been assessed through the study of hydrogeochemical characteristics and the water chemistry as it is considered the main source for drinking and agriculture activities in the region. The results of the relationship between Ca²⁺ + Mg²⁺ versus HCO₃^? + CO₃^2?, Ca²⁺ + Mg²⁺ versus total cations, Na⁺ + K⁺ versus total cations, Cl^? + SO₄^2? versus Na⁺ + K⁺, Na⁺ versus Cl^?, Na⁺ versus HCO₃^? + CO₃^2?, Na⁺ versus Ca²⁺, and Na⁺: Cl^? versus EC describe the mineral dissolution mechanism through the strong relationship between water with rocks in alkaline conditions with the release of Ca²⁺, Mg²⁺, Na⁺, K⁺, HCO₃^?, CO₃^2?, SO₄^2?, and F^? ions in the groundwater for enrichment. Furthermore, evaporation processes, groundwater depletion, and ion exchange contribute to the increased concentration of Na⁺ and Cl^? ions in groundwater. Anthropogenic sources are one of the main reasons for contamination of groundwater in the study area and for increasing the concentration of Mg²⁺, Na⁺, Cl^?, SO₄^2?, and NO₃^? ions. Results show the quality of groundwater in the study area is categorized as follows: HCO₃^? + CO₃^2? > Cl^? > SO₄^2? > NO₃^? > F^? and Na⁺ > Ca²⁺ > Mg²⁺ > K⁺. In conclusion, the results of TDS, TH, and chemical composition showed that 26% of the groundwater samples were unsuitable for drinking. About 28% of groundwater samples in the study area have a high concentration of Mg²⁺, Na⁺, and NO₃^? above the acceptable limit. Also, based on high SAR, 10% of the groundwater samples were not suitable for irrigation purposes.     

Evaluation of acidity in late Permian outcrop coals and its association with endemic fluorosis in the border area of Yunnan,Guizhou, and Sichuan in China

The junction area of Yunnan, Guizhou, and Sichuan provinces is the heaviest coal-burning endemic fluorosis zones in China. To better understand the pathogenicity of endemic fluorosis in this area, 87 coal samples from the late Permian outcrop or semi-outcrop coal seams were collected in eight counties of the junction area of Yunnan, Guizhou, and Sichuan provinces. The total fluorine and sulfate content, etc. in the coal was determined using combustion-hydrolysis/fluoride-ion-selective electrode method and ion chromatography, respectively. The results show that the total fluorine concentrations in the samples ranged from 44 to 382 µg g^?1, with an average of 127 µg g^?1. The average pH of the coals is 5.03 (1.86–8.62), and the sulfate content varied from 249 to 64,706 µg g^?1 (average 7127 µg g^?1). In addition, the coals were medium- and high-sulfur coals, with sulfur mass fraction ranging from 0.08 to 13.41%. By heating the outcrop coals, HF release from the coal was verified quantitatively without exception, while simulated combustion directly confirmed the release of sulfuric acid (H₂SO₄). The acid in coal may be in the form of acidic sulfate (\({\text{HSO}}_{4}^{ - }\)/H₂SO₄) because of a positive relationship between pH and \(p\left( {{\text{SO}}_{4}^{2 - } } \right)\) in the acidic coal. The possible reaction mechanism would be that a chemical reaction between the acid (H₂SO₄ or \({\text{HSO}}_{4}^{ - }\)) and fluorine in the coal occurred, thereby producing hydrogen fluoride (HF), which would be the chemical form of fluorine released from coal under relatively mild conditions. The unique chemical and physical property of HF may bring new insight into the pathogenic mechanism of coal-burning endemic fluorosis. The phenomenon of coal-burning fluorosis is not limited to the study area, but is common in southwest China and elsewhere. Further investigation is needed to determine whether other endemic fluorosis areas are affected by this phenomenon.     

Indoor and outdoor radon measurements at lung cancer patients’ homes in the dwellings of Rize Province in Turkey

In this study, indoor and outdoor radon (²²²Rn) surveys were carried out in the summer and winter seasons in homes of one hundred lung cancer patients in the year 2013–2014. The aim was to investigate the relationship between radon and cancer patients. Lung cancer patients completed a questionnaire concerning their living environment, various physical parameters and living habits. Pearson correlation and t tests revealed no meaningful results between radon concentrations, on one hand, and environmental and personal living habits, on the other hand. Consequently, the BEIR VI model was adapted and ²²²Rn exposure was estimated to be responsible for about 12% of the lung cancer incidences in the winter season and around 5% in the summer season in the Rize Province. However, due to the limited number of data and numerous parameters that could lead to lung cancer, the estimations done with the model should be taken very lightly. The annual effective doses due to inhalation of indoor and outdoor ²²²Rn were estimated to be, respectively, 1.43 and 0.94 mSv y^?1. The indoor and outdoor annual effective doses were, respectively, close and below the world annual effective dose (1.3 mSv y^?1). At the district level, the indoor annual effective dose equivalent in the ?yidere district was 4.52 mSv y^?1, which was 3.5 times greater than the world average. The number of patients in the majority of the houses in this district was more than one.     

Blood concentrations of lead,cadmium, mercury and their association with biomarkers of DNA oxidative damage in preschool children living in an e-waste recycling area

Reactive oxygen species (ROS)-induced DNA damage occurs in heavy metal exposure, but the simultaneous effect on DNA repair is unknown. We investigated the influence of co-exposure of lead (Pb), cadmium (Cd), and mercury (Hg) on 8-hydroxydeoxyguanosine (8-OHdG) and human repair enzyme 8-oxoguanine DNA glycosylase (hOGG1) mRNA levels in exposed children to evaluate the imbalance of DNA damage and repair. Children within the age range of 3–6 years from a primitive electronic waste (e-waste) recycling town were chosen as participants to represent a heavy metal-exposed population. 8-OHdG in the children’s urine was assessed for heavy metal-induced oxidative effects, and the hOGG1 mRNA level in their blood represented the DNA repair ability of the children. Among the children surveyed, 88.14% (104/118) had a blood Pb level >5 μg/dL, 22.03% (26/118) had a blood Cd level >1 μg/dL, and 62.11% (59/95) had a blood Hg level >10 μg/dL. Having an e-waste workshop near the house was a risk factor contributing to high blood Pb (r _s  = 0.273, p < 0.01), while Cd and Hg exposure could have come from other contaminant sources. Preschool children of fathers who had a college or university education had significantly lower 8-OHdG levels (median 242.76 ng/g creatinine, range 154.62–407.79 ng/g creatinine) than did children of fathers who had less education (p = 0.035). However, we did not observe a significant difference in the mRNA expression levels of hOGG1 between the different variables. Compared with children having low lead exposure (quartile 1), the children with high Pb exposure (quartiles 2, 3, and 4) had significantly higher 8-OHdG levels (β _Q2 = 0.362, 95% CI 0.111–0.542; β _Q3 = 0.347, 95% CI 0.103–0.531; β _Q4 = 0.314, 95% CI 0.087–0.557). Associations between blood Hg levels and 8-OHdG were less apparent. Compared with low levels of blood Hg (quartile 1), elevated blood Hg levels (quartile 2) were associated with higher 8-OHdG levels (β _Q2 = 0.236, 95% CI 0.039–0.406). Compared with children having low lead exposure (quartile 1), the children with high Pb exposure (quartiles 2, 3, and 4) had significantly higher 8-OHdG levels.     

Toxicity of the pyrethroid bifenthrin insecticide

Bifenthrin is a chiral synthetic pyrethroid insecticide that has been commonly used for agricultural and domestic pest control over the past decades. Due to its widespread application, residues of bifenthrin has been frequently detected in environmental media, residential areas and biota, thus posing potential risks to the health of wildlife and humans. In particular, bifenthrin exhibits high acute lethal toxicity to aquatic species, and it is the primary contributor to the toxicity of insecticides in waters. Additionally, bifenthrin can also cause sublethal toxic effects on various non-target organisms, including developmental toxicity, neurobehavioral toxicity, oxidative damage, immune toxicity and endocrine disrupting effects. Here we review recent studies about the fate of bifenthrin in the environment and biological systems, the toxicity of the chiral parent compound bifenthrin and the toxic effects of main metabolites. The adverse effects of bifenthrin, identified from both in vitro and in vivo studies, and the potential underlying mechanisms are presented. We discuss the enantiomeric difference in the toxicological effects of bifenthrin, since enantiomers of chiral compounds show different interactions with biological systems. Pyrethroid insecticides metabolites are not acutely toxic, but they have sublethal toxicity, such as endocrine disrupting effects and immunotoxicity. We provide emerging evidence for toxic effects of several main metabolites.     

Cyclodextrin-based supramolecular assemblies: a versatile toolbox for the preparation of functional porous materials

The discovery of ordered mesoporous materials in 1992 by Mobil Oil Corporation scientists has opened great opportunities for new applications in many emerging fields such as heterogeneous catalysis, biocatalysis, energy conversion, biosensors, photocatalytic devices and environmental technologies. Porous materials are grouped by the International Union of Pure and Applied Chemistry (IUPAC) into three classes according to their pore diameter: microporous (<?2 nm), mesoporous (2–50 nm) and macroporous (>?50 nm). One of the most versatile methods for the preparation of those materials is the soft template approach which combines the sol–gel process with molecular self-assembly. While the micelles formed by ionic or nonionic surfactants, as well as amphiphilic polymers, have been extensively used as templates, the supramolecular assemblies formed between cyclodextrins and block copolymers have been less investigated, despite their large chemical and structural diversity. This review article focuses mainly on nanostructured porous inorganic materials derived from cyclodextrins or cyclodextrin-based assemblies. More than 100 references are described and discussed, in which we look both at their synthesis and characterization, as well as their applications in the emerging fields of heterogeneous catalysis and photocatalysis. A special attention is paid to the evaluation of the critical parameters that need to be controlled for improving their (photo) catalytic performances.