Heavy metals in agricultural soils and crops and their health risks in Swat District,northern Pakistan

This study assessed the concentrations of heavy metals such as cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni) and zinc (Zn) in agricultural soils and crops (fruits, grains and vegetable) and their possible human health risk in Swat District, northern Pakistan. Cd concentration was found higher than the limit (0.05 mg/kg) set by world health organization in 95% fruit and 100% vegetable samples. Moreover, the concentrations of Cr, Cu, Mn, Ni and Zn in the soils were shown significant correlations with those in the crops. The metal transfer factor (MTF) was found highest for Cd followed by Cr > Ni > Zn > Cu > Mn, while the health risk assessment revealed that there was no health risk for most of the heavy metals except Cd, which showed a high level of health risk index (HRI ⩾ 10E-1) that would pose a potential health risk to the consumers.     

Cognitive performance among cohorts of children exposed to a waste disposal site containing heavy metals in Chile

Between 1984 and 1998, people living in Arica were involuntarily exposed to metal-containing waste stored in the urban area. The study aims to determine whether children who lived near the waste disposal site during early childhood experienced negative effects on their cognitive development. The cognitive performance was assessed using the Wechsler Intelligence Scale for Children. The exposure variable was defined by the year of birth in three categories: (1) Pre-remediation (born before 1999); (2) During-remediation (born between 1999 and 2003); and (3) Post-remediation (born after 2003). In the crude analysis, a difference of 10 points in the IQ average was observed between the group born in the pre- (81.9 points) and post-remediation period (91.1 points). The difference between both groups was five times higher as compared to children of similar age and socioeconomic status in other cities of Chile. This result could be related with a period of high potential for exposure to this contaminated site.     

The sensitivity of biomarkers for genotoxicity and acute cytotoxicity in nasal and buccal cells of welders

Welders are inhalatively exposed to fumes which contain genotoxic carcinogens and it was found in epidemiological studies that they have increased cancer rates which may be causally related to DNA damage. In order to assess their health risks and to find out which chemicals cause the adverse effects, bioassays can be performed which enable the detection of genetic damage. The aim of the present study was a comparative investigation with exfoliated buccal and nasal cells in regard to induction of chromosomal alterations and acute cytotoxicity in welders and unexposed controls (n = 22 per group). To elucidate the factors which account for genotoxic and cytotoxic effects, additional biochemical parameters were monitored reflecting the redox status as well as concentrations of different metals and 1-hydroxypyrene (1-OHP) in body fluids. We found in the nasal cells significant induction of alterations which are indicative for DNA damage, i.e. of micronuclei (MNi) and nuclear buds, while elevated rates of nuclear anomalies reflecting cytotoxic effects (condensed chromatin, karyorrhexis, karyolylsis) were detected in cells from both organs. The levels of certain metals (Cr, Cu, Mn, Mo, Ni), but not markers of oxidative damage were significantly higher in the body fluids of the welders. Multivariate Poisson regression analyses indicate that exposure to Mo (15% MNi increase by one standard deviation increase of Mo in serum), Ni (9% increase) and Mn (14% increase) are positively associated with the induction of MNi in nasal cells while Ni was associated with cytotoxic effects in both types of cells (12 and 16% increase). Taken together, our findings indicate that epithelial cells from the respiratory tract are suitable for the detection of DNA-damaging and cytotoxic effects in welders and can be used to assess health risks associated with genomic instability.     

Simulated downwind coal combustion emissions for laboratory inhalation exposure atmospheres

Exposure atmospheres for rodent inhalation toxicology studies were generated to enable the evaluation of biological responses to a simulated downwind coal combustion atmosphere. A composition representing a single test case of emissions components as they may exist tens to hundreds of miles from a coal-fired power plant was developed. The particulate matter (PM) was 99% sulfate (partially neutralized) and 1% ash. Sulfate was present in equimolar concentrations to sulfur dioxide (SO₂). Gaseous nitrogen species included nitrogen monoxide (NO), nitrogen dioxide (NO₂), and nitric acid (HNO₃). At the high-exposure level, the gaseous species target concentrations were 0.2?ppm SO₂, 0.6?ppm NO, 0.3?ppm NO₂, and 0.1?ppm HNO₃. The test atmosphere was produced by combining effluent from a laboratory coal combustor with sulfate generated through an evaporation–condensation generator. These atmospheres were used to conduct inhalation toxicology studies that have been previously reported.     

Perspectives on phytoremediation of zinc pollution in air,water and soil

In this article, we discuss the phytoremediation of Zn pollution in the environment and the mechanism of plant resistance focusing on the mycorrhiza and subcellular mechanisms affecting metal binding and efflux in plants. Phytoremediation is a green low-cost technology that use plants to remove heavy metals (HMs) from soil. As part of this, it is necessary to consider the plant's tolerance to for example zinc (Zn) together with the plant's ability to accumulate and adapt to the specific local environment. During the process of restoring ecosystem contaminations, pH, organic matter, root exudates and microbial biomass affect the efficiency of phytoremediation while considering chemical modification, biosynthesis, microbial assistance and gene technology. However, obstacles remain in terms of for example chemical modifications that may cause either new pollution or disrupt the plant-microorganism symbiosis while other applications such as genetic engineering to change plant traits and function thereby improving heavy metal tolerance and absorption. The selection of gene fragments is complicated and requiring careful considerations due to environmental and human health side effects. Furthermore, using biochar may help to reduce the costs and increase the efficiency of plant phytoremediation. At the same time, there is an urgent need to combine nanotechnology and use of artificial chelating agents and plant hormones to screen the microbiome conducive to plant Zn absorption in order to improve the efficiency of phytoremediation.     

Oral exposure to cadmium and mercury alone and in combination causes damage to the lung tissue of Sprague-Dawley rats

Environmental presence and human exposure to heavy metals in air and cigarette smoke has led to a worldwide increase in respiratory disease. The effects of oral exposure to heavy metals in liver and kidney structure and function have been widely investigated and the respiratory system as a target is often overlooked. The aim of the study was to investigate the possible structural changes in the lung tissue of Sprague-Dawley rats after oral exposure for 28 days to cadmium (Cd) and mercury (Hg), alone and in combination at 1000 times the World Health Organization’s limit for each metal in drinking water. Following exposure, the general morphology of the bronchiole and lungs as well as collagen and elastin distribution was evaluated using histological techniques and transmission electron microscopy. In the lungs, structural changes to the alveoli included collapsed alveolar spaces, presence of inflammatory cells and thickening of the alveolar walls. In addition, exposure to Cd and Hg caused degeneration of the alveolar structures resulting in confluent alveoli. Changes in bronchiole morphology included an increase in smooth muscle mass with luminal epithelium degeneration, detachment and aggregation. Prominent bronchiole-associated lymphoid tissue was present in the group exposed to Cd and Hg. Ultrastructural examination confirmed the presence of fibrosis where in the Cd exposed group, collagen fibrils arrangement was dense, while in the Hg exposed group, additional prominent elastin was present. This study identified the lungs as target of heavy metals toxicity following oral exposure resulting in cellular damage, inflammation and fibrosis and increased risk of respiratory disease where Hg showed the greatest fibrotic effect, which was further, aggravated in combination with Cd.     

Characterization of Printed Circuit Boards for Metal and Energy Recovery after Milling and Mechanical Separation

The proper disposal of electrical and electronic waste is currently a concern of researchers and environmental managers not only because of the large volume of such waste generated, but also because of the heavy metals and toxic substances it contains. This study analyzed printed circuit boards (PCBs) from discarded computers to determine their metal content and characterized them as solid waste and fuel. The analysis showed that PCBs consist of approximately 26% metal, made up mainly of copper, lead, aluminum, iron and tin, as well as other heavy metals such as cadmium and nickel. Comparison with the results of other studies indicated that the concentration of precious metals (gold and silver) has declined over time. Analysis of the leachate revealed high concentrations of cadmium and lead, giving the residue the characteristics of hazardous waste. After milling the PCBs, we found that larger amounts of metal were concentrated in smaller fractions, while the lightest fraction, obtained by density separation, had a gross calorific value of approximately 11 MJ/kg, although with a high ash content. Milling followed by density separation proved potentially useful for recovery of metals and energy-rich fractions.     

The alternate iron transport pathway: mobilferrin and integrin in reticulocytes

Iron transport in reticulocytes is known to occur via the well-described transferrin-receptor–endosome pathway. An alternative pathway for iron transport independent of transferrin has been postulated in reticulocytes and other cells. Transport of iron into reticulocytes from ferric citrate solutions was shown to be saturable and independent of transferrin. During transport of iron from ferric citrate, both cell surface integrins, and a soluble protein, mobilferrin, were labelled. This demonstrated that the reticulocyte transferrin independent pathway for iron transport involved integrins and mobilferrin similar to intestinal absorptive cells. This pathway would be expected to transport iron into cells under conditions of iron overload and was capable of providing iron for haemoglobin synthesis. Mobilferrin was also radiolabelled when radioiron labelled transferrin was incubated with reticulocytes and this occurred with a different time course than was observed following reticulocyte exposure to radiolabelled ferric citrate. This suggested that mobilferrin may serve as an intermediary in both pathways.     

不同产地冻干地黄中5种重金属及有害元素的含量测定

摘 要 目的： 用火焰原子吸收分光光度计和原子双道荧光光度计分别对不同产地冻干地黄中的Pb、Cd、Cu、As和Hg 5种重金属和有害元素进行检测。方法: 采用硝酸-高氯酸对样品进行消化后,采用原子吸收分光光度法测定Pb、Cd和Cu含量,采用原子荧光光度法测定As和Hg的含量。 结果: 各元素线性关系良好,相关系数均大于0.997 4,平均回收率为97.88%～100.90%,RSD为0.019%～4.20%（n=6）,同时发现10批样品中的4批样品部分重金属和有害元素超过《中国药典》限量标准。 结论:该方法准确度高,操作简便,快捷,适用于冻干地黄中重金属和有害元素的测定。