The U.S. Geological Survey reported on February 11 a new study that shows approximately 45% of U.S. public-supply wells and about 37% of domestic-supply wells have concentrations of lithium that could present a potential human-health risk.
Lithium is an alkali metal that occurs naturally in some groundwater where that groundwater interacts with lithium-containing minerals or saline water.
Certain amounts of lithium can cause adverse health effects, primarily impaired thyroid and kidney function. Presently lithium is not regulated in drinking water in the United States.
The USGS, in collaboration with the U.S. Environmental Protection Agency, calculated a nonregulatory health-based screening level (HBSL) for drinking water of 10 micrograms per liter (µg/L) or parts per billion (ppb) to provide context for evaluating lithium concentrations.
Elevated levels were found primarily in samples of untreated groundwater from drinking-water wells in arid regions and in “old” groundwater—that is, groundwater that recharged the aquifer before 1953. The most elevated lithium concentrations were measured in wells that tap unconsolidated clastic aquifers (aquifers composed of sand or similar materials) in the western United States.
The USGS compiled data for lithium measured in untreated groundwater from 1464 public-supply wells and 1676 domestic-supply wells during 1991-2018. The study was designed to collect data representative of groundwater used as a source of drinking water at the national- and regional-aquifer scale. Groundwater in the aquifers sampled represents 80% of groundwater used for public supply in the country and as a source of drinking water for about 100 million people.
Lithium was just added to the EPA’s proposed Unregulated Contaminant Monitoring Rule in January. The rule is used by the EPA to collect data for contaminants that are suspected to be present in drinking water and that do not have health-based standards set under the Safe Drinking Water Act.