| As the well known environmental carcinogens and teratogens, Cd have been classified as the IA environmental carcinogens by International Agency for Research on Cancer(IARC), and World Health Organization (WHO) regard it as a priority food contaminants for research. Cadmium exposure is mainly due to inhalation, ingestion of food and water uptake. Cadmium is a toxic heavy metals what can be in the long-term accumulation in the human body and the environment, and the half-life in the human body is up to10-35years. As for the non-essential elements for the growth of the body, a small amount enter the body through the bioaccumulation can cause a series damage to kidney, lung, liver, testis, brain, blood system, eventually lead to death of the patient.As a new substance, nanomaterials are widely used in the fields such as new materials%new energy resources%environmental protection biological medicine. The mass production and widely use in the production and life, nanomaterials can be release into environment and diffusion. Although there is no direct result on nanotoxicity to human health, its potential environmental and health risks has been a growing concern. For environmental processes and environmental biological effection, some studies have been carried out and achieved some results, but the level of awareness has lagged far behind the pace of development of the production and application of nanomaterials.Nanomaterials released into environment will inteact inevitably with conventional pollutants. Due to the special characterization of the nanomaterial, leading to the migration of adsorbed contaminants. Heavy metal pollutants are adsorbed onto nanomaterials, their environmental behavior and possible biological effects may change, lead to the unknown environmental threats. At present, the amount of research about interaction between nanomaterials and pollutants is little, different biological effects resulting from its complexes are rarely reported. Previous study of this subject show that the toxicity of titanium dioxide nanomaterials is little. Based on these, TiO2-NPs was used to inteact with pollutants Cd in our subject, and study its impact on biological effects.Due to simple structure, transparent body, easy to observe, biological characteristics and short reproductive cycle, Caenorhabditis elegans were used as famous model organisms of incomparable advantages in the assessment of toxic substances in the environment. Though interactions between TiO2-NPs and Cd and expose to C.elegans, the biological affection was assessed. Experimental data may contribute to the use of nano-materials and environmental as sessment.Result show that TiO2-NPs adsorbed Cd rapidly(4h), its adsorption capacity for Cd constant qm=8.574μg/mg. By using the mutated strains that was deficient in DNA damage and repair, the lethality effects of cadmium exposure were studied by assaying the48h LC50. The result show that the mutated strain abl-1(okl71) and ced-3(n717) exhibited more sensitive to cadmium than that of N2, while the hus-1(op241) showed an intensified resistance to cadmium exposure. By comparing body length, survival and apoptosis of C.elegans, high concentrations of Cd have serious impact on the growth and development of C.elegans. TiO2-NPs play an important role of doing favor to the recovery of development of C.elegans.This study provided preliminary safety assessment of the use of nanomaterials, laid the foundation for further study of the biological effects of composites which contain nanomaterials and pollutants, and provided theoretical guidance of the use of TiO2-NPs as an adsorbent of pollutants. TiO2-NPs reduce the levels of apoptosis caused by Cd. So TiO2-NPs reduce the toxicity of Cd to C.elegans. |
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