Genotoxicity and Health Risk of Seawater Desalination Based on Reverse Osmosis: A Case Study of Two Seawater Desalination Plants in Zhoushan, China

Typically, the shortage of freshwater will limit the social and economic development of island regions. As a non-conventional, high-quality water source, desalinated seawater can be incorporated into the urban water supply system. The genotoxicity of disinfection by-products in drinking water was always viewed as a concern for human health. However, only a few studies were conducted based on this issue of desalinated seawater. In this study, the comet assay was conducted to investigate the genotoxicity caused by organic extracts in the specific drinking water produced in two full-scale desalinated seawater purification plants from the Zhoushan Islands in eastern China. The water samples were collected from four different locations along the treatment train in the plants. The quality of desalinated seawater conformed to the national standards for drinking water in China, except for the higher boron content. The results of the comet assay showed that all the organic extracts from the water samples were able to induce different levels of DNA damage on HL-60 cells (K finished water = 6.635 and 7.698, respectively). Compared with that from the water plants with fresh source water, the genotoxicity of the finished water of the seawater desalination plant was determined to be the lowest. The correlations between desalinated seawater consumption and two important chronic diseases, namely hypertension and coronary heart disease, could not be supported by the current data of epidemiological investigation. These results demonstrate the genotoxicity of the desalinated seawater was, in fact, much lower than the conventional drinking water with fresh source water.