The United States Geological Survey (USGS) released on March 5, 2019 a first-of-its-kind study on the prevalence of pharmaceuticals and hormones within the country’s groundwater aquifers. Previous, smaller research studies looked at this issue on a more limited basis, but the USGS study included raw water samples from over 1000 sites in 46 states, representing 60% of the groundwater used for drinking by an estimated 80 million Americans. For this study, researchers tested for 103 pharmaceuticals and 21 hormones.
Of the 844 sites representing public water supplies, only 5.9% of samples detected at least one of these compounds. Of the 247 domestic water supply sites tested, only 11.3% tested positive for at least one compound. When these pharmaceuticals and hormones were detected, they were at levels below human health benchmarks. Human-health benchmarks were taken from the Minnesota Department of Health or from Australian guidelines where available. Only one sample of one pharmaceutical – hydrocortisone – exceeded those guidelines. Notably, detections were most common in shallow wells and the pharmaceuticals and hormones most frequently detected were not necessarily the compounds most heavily used, but instead those compounds that are most soluble and therefore move through the groundwater more easily.