Study On Joint Toxicity Of A Mixture Of Eight Common Heavy Metal Pollutants In Ningbo

Objective: To prevent the adverse health effects of heavy metal pollution, an in vitro studyusing a mouse epithelial cell line (JB6cells) was conducted to study on the joint toxicity of amixture of eight common heavy metal pollutants in Ningbo.Methods: A mixture including eight common heavy metals was prepared according to theirpollution proportion in the water system in Ningbo area.10μM antioxidant polyphenols(Epigallocatechin gallate, EGCG) was tested to antagonize the toxicity effects of this mixture.MTT assay, flow cytometry and laser scanning confocal microscopy were used to detect cellviability, apoptosis and cell cycle, and oxidative stress, respectively. Luciferase assay wasemployed to analyze the cell transcription factor AP-1and NF-kB expression. Protein expressionlevels were detected by western blot.Results: After treatment for24h, cell viablity was decreased gradully as the mixtureconcentration increasing. Flow cytometry showed that cells were arrested at S phase, and the rateof apoptosis was induced. Intracellular ROS was increased with the increasing of concentration ofthe mixture after staining with H2DCFDA、DHA and Hoechst under the confocal microscopy.Lucifferase activity of AP-1and NF-kB showed a significant increase after12h treatment withdifferent concentrations of the mixture. Western blot showed the expression of C-jun and p65weregradually increased with the increasing of concentration of the mixture.Treatment with supplement of10μM EGCG showed significant inhibition on the toxic effectsinduced by the treatment with the heavy metal mixture alone.Conclusions: Mixtures of heavy metals can arrest the cell cycle at S phase and induced cellapoptosis and oxidative stress. Up-regulation of transcription factor AP-1and NF-kB luciferaseactivity as well as C-jun and p65protein levels indicate the carcinogenicity of the mixture.Antagonism of the EGCG on these toxicities implies a protection against the adverse health effectsinduced by a mixture of eight common heavy metal pollutants.