Combination Toxicity Of Cadmium Chloride And Nanometer Titania, EDTA And Health Risk Evaluation Of Soil Pollution Of Cadmium In Typical Areas

The International Agency for Research on Cancer (IARC) defines cadmium to be IA carcinogen in 1993, which means that cadmium is a definite carcinogen.Cadmium can cause lung cancer, prostate cancer and testis cancer and has germ cell mutation and development toxicity, too. Animal experiments and censuses of population show that there is also reproduction toxicity. Cadmium also has organs and tissues toxicities, including respiratory system, alimentary system, kidney, ossature, nervous system, cardiovascular system and other system. Kidney is the target organ of cadmium chronic toxicity, the major damage position is proximal convoluted tubule. The most important health effect of cadmium is ossature damage. The world famous ita ita disease which first happened in Fu San county in Japan was caused by cadmium pollution, and the character symptoms were osteomalacia and osteoporosis.Cadmium, a non-essential element, is rare in natural environment and the concentration is low. There is cadmium in crust, rocks and waters. Natural environment influence the concentration in foods. The average concentration is 0.1×10 -4 mg/ kg in crust, 5×10 - 8 mg/ kg inglacier and 4.5×10 - 6 mg/ kg in organic matter particle of marine facies. Cadmium compounds coexist with many other metal ore, such as zinc and lead, so the polluted water that produced by smelting other metals include cadmium. Zinc ores generally contain 0.1-0.5% cadmium, some can reach up to 2-5%.There are many typical cadmium pollution areas in China according to the dates from National Environmental Protection and Health Key Laboratories, such as Dayu Jiangxi, Wenzhou Zhejiang. The causes of cadmium pollutions are excess exploits or inorganization volleies. Owing to harmful healthy damage and serious cadmium pollution, much attention has to been paid to its effect.Part 1 Cello-oxidative Damage of HEK293t Cells Induced by Combination of CdCl₂ and nano-TiO₂, CdCl₂ and EDTAIn this part it was invested that cello-oxidative damage of Human Embryo Kidney 293t (HEK293t) cells induced by CdCl₂ and nano-TiO₂, CdCl₂ and EDTA. The cyto-toxicity was studied using the Toxic Unit approach. In order to design concentrations, first the median lethal concentrations (LC50) of CdCl₂, nano-TiO₂ and EDTA were determined, and then different toxic units(0TU,0.25TU,0.5TU,0.75TU,1TU,1.25TU) of CdCl₂ and nano-TiO₂, CdCl₂ and EDTA were mixed so that the total toxic units are 0.75TU,1TU,1.25TU. RT-PCR technique was used to detected the expressions of gene HO-1 and OGG1. Activities of antioxidases and concentrations of ROS were also detected to evaluate the conjoined oxidative damage of CdCl₂ and nano-TiO₂, CdCl₂ and EDTA on HEK293t cells.The results showed that the interaction between CdCl₂ and nano-TiO₂ was synergism, and that between CdCl₂ and EDTA was antagonism. Influences of concentration and ratio to these indexes were different meant that sensitivities of all these indexes were various. The ROS content was most sensitive among all these indexes, so it was recommended to indication index of oxidative damage. The oxidative damage mechanism of CdCl₂ was not clear, the mechanisms of synergism between CdCl₂ and nano-TiO₂ and antagonism between CdCl₂ and EDTA needed to be studied in future.Part 2 Health Risk Evaluation of Soil Pollution of Cadmium in a Typical Area in ChinaThe cadmium pollution becomes more and more severely day after day. There are 12000 square kilometers cadmium polluted farmlands of 11 irrigation districts. The concentration of heavy polluted soil in Zhangshi irrigation district in Shenyang even reaches up to 5-7mg/kg, content in rice achieves 0.1-0.2mg/kg. Cadmium can't be biodegraded, and concentrations in water and soil grow every year. Cadmium can be accumulated in plants and animals (such as rice in polluted areas, shells, livers and kidneys), then finally accumulated in human body.The research chooses 3 villages: A, B and C.A is 2 kilometers away southeast from the smeltery. B is 4 kilometers away southeast from the smeltery. C is 30 kilometers away northwest from the smeltery. A and B is the contaminated Plot. C is the Control plot. The natural environments, social environments, living habits and economic statues are similar. Then the researchers detected the concentration of cadmium in human body, soil, drinking water and crops. Those basal dates could support environmental management, environmental construction of cadmium.The investigation showed that there was health risk in all the three villages, and had paid extremely bad effect on inhabitants'health. Cadmium in waters and airs finally transported into soil by many channels, so soil was one of the most important pathways to environment pollution. Though measures had been taken to the contaminated zone, the cadmium concentration in soil exceeded national standard. It cued that cadmium soil pollution was larvaceous, hysteretic, cumulative and nonreversible, so it was hard to govern. Rice and vegetables enriched cadmium through food chain, the concentration were much higher than standard. Concentration in human bodies grew by eating cadmium polluted foods, and then the kidney damage rates rose up. It suggested that human health had been damaged by cadmium pollution. In addition, concentrations in soil, rice and vegetables of control plot excelled national standard. It suggested there was new pollution resource in control plot.