https://phys.org/news/2018-06-treatment-contaminants.html > According to the results of the project, the purification process was effective in removing pathogenic microbes, but small amounts of chemical substances were identified in the artificial groundwater. > "The observation raises questions about the health risks caused by chemical contaminants. However, based on a risk assessment, none of the individual chemical contaminants exceeded the tolerable daily intake limit," explained principal investigator Päivi Meriläinen of Finland's National Institute for Health and Welfare.