Studying On The Biological Toxic Effects Of Multiple Typical Pollutants Based On The In Vitro Exposure Mode

The existence of a large number of pollutants gave a high stress on the healthy development of organism and ecosystem. When were absorbed by organism, these pollutants could result in some degree of toxic effects. The current base of environmental pollutants was quite huge, and what is worse, there were thousands of new pollutants being released to the environment every year. It is very essential to monitor their toxicities and to evaluate their biological impacts. In our experiment, we studied the biological effects of multiple pollutants by in vitro exposure mode. In this first part, we conducted a study on the effects of heavy metals and brominated flame retardants on antioxidant system in Mossambica tilapia liver. Besides, we explored the potential of the parameters in Mossambica tilapia liver antioxidant system to serve as biomarkers to evaluate the adverse effects of heavy metal and BFRs pollution. In this second part, we investigated the single and joint genetic toxicity of multiple pollutants incluing heavy metals, synthetic dyes, and bromate et al. on THP-1cell line by comet assay. The main research contains:(1) Determination methods for the three indicators under laboratory conditions were optimized, and applied to the microplate reader. The modified methods are easy, rapid and sensitive. It is worth mentioning that the improved methods could assay multiple samples simultaneously. The modified methods were used to study the effects of four heavy metals and typical brominated flame retardants on hepatic antioxidant system of Mossambica tilapia in vitro. The results indicated that GSH increased firstly and then decreased with the increase of heavy mental dose and it was very sensitive. GST had no obvious change in low concentrations whereas it was inhabited significantly at high concentrations. There was obvious dose-response relationship between GST activity and doses of heavy mentals. The GSH and GST were potential to be biomarkers of heavy mentals. After the exposed to four kinds of BFRs, compounds with low bromine content (BDE-47and TBBPA) could induced the GST and SOD activity more, which means that compounds with low bromine content might result in higher adverse bio-effects level. Moreover, the GST and SOD were sensitive to the BFRs. The GST could respond obviously to all the tested BFRs except for TBBPA at concentration less than1ng/L, and the SOD was induced significantly by all tested BFRs at dose less than10ng/L. Moreover, a good dose-response relationship between GST, SOD activity and doses of more than one BFRs was obtained in certain concentrations. Therefore, the GST and SOD were very potential candidates to serve as BFRs biomarkers.(2) Comet assay was optimized, and applied to detect the DNA damage induced by multiple chemicals. Results of single tests indicated that heavy mentals were most toxic, and the second most toxic is synthetic colors, then the the third most toxic is acrylamide. Bromate showed the weakest genetic toxicity on THP-1cells in vitro among all tested compounds.(3) The results of comet assay in joint exposure showed that the co-existance of chrysoidine G and other compounds could increase the DNA damage toxicity significantly at most concentrations. The co-existance of acrylamide and other chemicals increased the genetic toxicity slightly but there were no obviously difference at most doses. It revealed that combined exposure is a complicated process and it is easily affected by many factors. Therefore, It is necessary to take mixtures effects into consideration when set the relevant standards of pollutants.(4) Both the single and joint exposure results obtained by comet assay showed a dose-response relationship between DNA damage effects and concentrations, which suggested that comet assay was a suitable method to detect the DNA damage induced by multiple pollutants in vitro.(5) In this experiment, we studied the genetic toxicity on THP-1cells and effects on hepatic antioxidant system of Mossambica tilapia by in vitro mode. As compared to in vivo exposure, the in vitro exposures are very sensitive; and it is easy to control experimental condition in the in vitro exposure to decrease the individual difference effect to the lowest, which increased reproducibility. The in vitro exposure allows to choose different target organ or cells as objects, which generate good specificity and flexibility. Moreover, the in vitro exposure allows the simultaneous analysis of multiple chemical biological effects within a single experiment, which is very important for the preliminary toxicity screening of thousands of pollutants that existed in environment. These in vitro results in the present study was similar with that obtained from in vivo tests to some extent, which indicated that the in vitro exposure mode is a potential method which could be used in environmental toxicology combined with in vivo methods.