Bromate Causes Significant Cytotoxicity and Modulation of the Inflammatory Response

Abstract

Bromate is used as an additive in bread and also a disinfection by-product of hypochlorite treated and ozonated waters. The effect of bromate (as potassium bromate) on the proliferation of U937 cells and activation of U937-derived macrophages was investigated. First, U937 cells were incubated with bromate at different concentrations and later cell viability was assessed via the trypan blue dye staining and reduction of MTT. The production of reactive oxygen species (ROS) was also measured via the DCHF-DA assay. In further experiments, the U937 cells were transformed to the macrophage form via treatment with phorbol-12-myristate-13-acetate before incubated with different concentrations of bromate. Later the production of NO, TNF-a, and IL-6 was evaluated as indices for the activation of macrophages. The results revealed that bromate caused significant cell death when compared to control and was concentration-dependent (p < 0.05). Bromate also significantly produced reactive oxygen species in U937 cells, and also stimulated the production of NO, TNF-a, and IL-6 in U937-derived macrophages. This indicate that bromate causes significant cytotoxicity and also trigger cells to produce significant amount of intracellular reactive oxygen species. Bromate also activated macrophages thus indicating that the cytotoxicity of bromate could involve the modulation of the inflammatory response.