Cancer and Non-Cancer Health Risk from Eating Cassava Grown in Some Mining Communities in Ghana

Food crops such as cassava, cocoyam and other tuber crops grown in mining communities uptake toxic or hazardous chemicals such as arsenic, and cadmium, from the soil. Cassava is a stable food for Ghanaians. This study evaluated human health risk from eating cassava grown in some mining communities in Ghana such as Bogoso, Prestea, Tarkwa and Tamso, which are important mining towns in the Western Region of Ghana. The study evaluated cancer and non-cancer health effects from eating cassava grown in the study areas in accordance with US Environmental Protection Agency’s Risk Assessment guidelines. The results of the study revealed the following: cancer health risk for Tamso, 0.098 (RME – Reasonable Maximum Exposure) and 0.082 (CTE – Central Tendency Exposure). This means that approximately 10 and 8 out of 100 resident adults are likely to suffer from cancer related cases by RME and CTE parameters respectively. For Prestea, we have 0.010 and 0.12, which also means that approximately 1 out of 100 and 10 resident adults out of 100 are also likely to suffer from cancer related diseases by RME and CTE parameters. The results of the study obtained were found to be above the acceptable cancer risk range of 1× 10⁻⁶ to 1× 10⁻⁴, i.e., 1 case of cancer out of 1 million or 100,000 people respectively.     

Biomonitoring in the Boulder River Watershed, Montana, USA: Metal Concentrations in Biofilm and Macroinvertebrates, and Relations with Macroinvertebrate Assemblage

Portions of the Boulder River watershed contain elevated concentrations of arsenic, cadmium, copper, lead, and zinc in water, sediment, and biota. We measured concentrations of As, Cd, Cu, Pb, and Zn in biofilm and macroinvertebrates, and assessed macroinvertebrate assemblage and aquatic habitat with the objective of monitoring planned remediation efforts. Concentrations of metals were generally higher in downstream sites compared with upstream or reference sites, and two sites contained metal concentrations in macroinvertebrates greater than values reported to reduce health and survival of resident trout. Macroinvertebrate assemblage was correlated with metal concentrations in biofilm and macroinvertebrates. However, macroinvertebrate metrics were significantly correlated with a greater number of biofilm metals (8) than metals in invertebrates (4). Lead concentrations in biofilm appeared to have the most significant impact on macroinvertebrate assemblage. Metal concentrations in macroinvertebrates were directly proportional to concentrations in biofilm, indicating biofilm as a potential surrogate for monitoring metal impacts in aquatic systems.     

LB复合膜选择性检测水中痕量镉离子的方法研究

开发了一种利用LB复合膜选择性地检测水中痕量镉离子的技术方法,研究了最佳LB复合膜检测器的制作条件.用表面活性剂十二烷基-(2-噻唑偶氮)间苯二酚(DTAR)作显色剂,对乙烯基硬脂酸盐(PVS)、十八烷基异丁烯酸盐(PMOA)、乙烯基-N-氨基甲酸十八烷基酯(PVOC)和顺丁烯二酸酐-1-十八烯(PMO)4种聚合物进行了强度实验,得出稳定的检测器结构,即偶数层DTAR上附着单层PVOC的LB复合膜.经过灵敏度实验,制作出最佳LB复合膜检测器DTAR6-PVOC1,在pH为7.5,温度40℃且搅拌的反应条件下,该检测器可以在10 min之内检出10-7mol/L镉,并可目视定性及半定量检测出水中痕量镉离子.水中可能共存的离子中只有CU2+和Zn2+会干扰镉离子的检测,需要抑制.      

利用隆线溞趋光行为检测水体中五氯酚钠和镉的研究

采用自主选育的隆线溞单克隆体作为试验生物,研究了五氯酚钠(PCP-Na)和镉对隆线溞趋光指数的影响,并与急性毒性试验方法进行了比较.结果表明,在试验浓度范围内,水溞的趋光指数分别随五氯酚钠和镉浓度的升高而降低,呈极显著线性关系,说明隆线溞趋光指数的变化可以指示水体中这2种毒物的生物有效浓度.PCP-Na使隆线溞趋光指数(3h)发生显著改变的下限浓度为0.18 mg·L～,远低于LC50(96 h)(0.59 mg·L-1),上限浓度大于3.20 mg·L-1,也远高于LC50(24h)(0.73 mg·L-1),表明隆线溞趋光指数法比急性毒性试验法的灵敏度高,检测范围大,耗时短.在试验溶液范围内,五氯酚钠和镉之间不存在明确的相互作用关系.     

尿素基纤维的制备及对水中Cu2+和Cd2+的吸附

以棉纤维为原料,经氯化和取代反应,制得尿素基纤维并用于水中Cu^2＋和Cd^2＋的吸附,考察了各种因素对吸附效果的影响。尿素基纤维对Cu^2＋和Cd^2＋的吸附可用Langmuir等温吸附方程描述,吸附过程可看成单层吸附。较佳吸附条件：重金属离子溶液pH为5,流量为7mL／min。用过的尿素基纤维经2mol／L的盐酸洗脱再生后,对Cu^2＋的吸附、解吸、再吸附的性能良好,可重复使用。     

Oxidative stress and DNA damages induced by cadmium accumulation

Experimental evidence shows that cadmium （Cd） could induce oxidative stress and then causes DNA damage in animal cells, however, whether such effect exists in plants is still unclear. In the present study, Vicia faba plants was exposed to 5 and 10 mg/L Cd for 4 d to investigate the distribution of Cd in plant, the metal effects on the cell lipids, antioxidative enzymes and DNA damages in leaves. Cd induced an increase in Cd concentrations in plants. An enhanced level of lipid peroxidation in leaves and an enhanced concentration of H2O2 in root tissues suggested that Cd caused oxidative stress in Vicia faba. Compared with control, Cd-induced enhancement in superoxide dismutase activity was significant at 5 mg/L than at 10 mg/kg in leaves, by contrast, catalase and peroxidaseactivities were significantly suppressed by Cd addition. DNA damage was detected by neutral/neutral, alkaline/neutral and alkaline/alkaline Comet assay. Increased levels of DNA damages induced by Cd occurred with reference to oxidative stress in leaves, therefore, oxidative stress induced by Cd accumulation in plants contributed to DNA damages and was possibly an important mechanism of Cd-phytotoxicity in Vicia faba plants.     

Thermodynamics and kinetics of cadmium adsorption onto oxidized granular activated carbon

Cadmium sorption behavior of granular activated carbon oxidized with nitric acid was systematically studied by sets of the equilibrium and time-based experiments under various conditions.The cadmium adsorption capacity of oxidized granular activated carbon enlarged with an increase in pH,and reduced with an increase in ionic strength.Experimental data were evaluated to find out kinetic characteristics.Adsorption processes were found to follow pseudo-second order rate equation.Adsorption isotherms correlate well with the Langmuir isotherm model and the maximum sorption capacity of cadmium evaluated is 51.02μmol/g.Thermodynamic parameters were calculated based on Van't Hoff equation.Equilibrium constant Kd was evaluated from Freundlich isotherm model constants,Langmnir isotherm model constants,and isotherms,respectively.The average change of standard adsorption heatΔH~0 was -25.29 kJ/mol.NegativeΔH~0 andΔG~0 values indicate the adsorption process for cadmium onto the studied activated carbon is exothermic and spontaneous.The standard entropyΔS~0 was also negative,which suggests a decrease in the freedom of the system.     

Metal contents of marine turtle eggs (Chelonia mydas; Lepidochelys olivacea) from the tropical eastern pacific and the implications for human health

Concentrations of eight elements were measured in Chelonia mydas and Lepidochelys olivacea eggs collected along the Pacific coast of Panama. Manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), and mercury (Hg) concentrations were similar to previous reports of these species from around the world, while lead (Pb) was lower than previous reports. Cd posed the highest health risk to people who regularly eat the eggs, with average consumption rates leading to target hazard quotients (THQ) of up to 0.35 ± 0.15. Our conclusions indicate that current turtle egg consumption in isolated, coastal Pacific communities may pose a health concern for young children, and that youth and young adults should limit their consumption of turtle eggs to reduce their total intake of nonessential metals.     

聚(丙烯酸-co-丙烯酰胺)/膨润土/腐植酸钠三维网络凝胶吸附剂对Cd2+吸附性能研究

制备了一种聚(丙烯酸-co-丙烯酰胺)/膨润土/腐植酸钠三维网络凝胶吸附剂,重点考察了吸附剂对Cd2+吸附的pH依赖性、吸附动力学和吸附等温线.结果表明,Cd2+溶液pH值对吸附容量有较大影响.在pH=8、吸附时间30 min、Cd2+溶液初始浓度0.02 mol/L和吸附剂用量0.10 g的条件下,吸附剂对Cd2+的饱和吸附量可达294.7 mg/g.与膨润土相比,三维网络凝胶吸附剂具有更高的吸附容量和更快的吸附速率.     

碳酸镁与镉离子的吸附和沉淀作用研究

以碳酸镁为吸附剂,在镉离子初始浓度为0~6 mmol/L,初始pH值为4和7的条件下,研究了碳酸镁与镉离子的吸附与沉淀作用。结果表明,由于碳酸镁的溶解及与体系中氢离子的中和,碳酸镁—镉体系的最终pH值为10.4左右;体系的平衡pH值随着镉离子初始浓度的增加而减小;体系中镉的平衡浓度随着初始镉离子浓度的增加缓慢上升;碳酸镁对镉的吸附等温线为折线型,不符合Freundlich和Langmuir模型,符合伪二阶吸附动力学模型。结合碳酸镁吸附镉前后固相表征的结果,说明碳酸镁与镉离子的作用机制随着镉离子浓度的增加,从离子交换发展为离子交换和表面配位反应并存,最后表现为表面沉淀。