In January 2024, Prestonsburg City’s Utilities Commission’s customers received a public notice within their billing that provided information about PFAS (per- and polyfluoroalkyl substances) and lithium which was tested in the drinking water throughout the year of 2023. These compounds were part of what the EPA calls UCMR 5 (the Fifth Unregulated Contaminant Monitoring Rule) which consisted of 30 different compounds. The UCMR 5 is part of the Safe Drinking Water Act that requires all public water systems to sample the drinking water once every five years for the 30 unregulated contaminants that are specified by the EPA. In 2023, EPA specified 29 compounds that make up PFAS and the 30th contaminant was lithium.
The public notice that the customers received provided information explaining what UCMR 5 is, what are PFAS, EPA’s proposal on PFAS, Prestonsburg’s sample results on the six PFAS compounds that the EPA is proposing to provide enforceable levels and Prestonsburg’s only detectable sample result from UCMR 5: lithium. The Method Detection Limit (MDL) that the EPA purposed for lithium was 7,500 ppt (parts per trillion). The MDL procedure is designed to be straightforward technique for estimation of the detection limit for a broad variety of physical and chemical methods. According to the EPA: “The method detection limit (MDL) is defined as the minimum concentration of substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero and is determined from analysis of a sample in a given matrix containing the analyte.” (Method Detection Limit – Frequent Questions | US EPA)
Although Prestonsburg did detect lithium in the range of 12,000 ppt to 33,600 ppt, which is above EPA’s MDL of 7,500 ppt, EPA has not established a non-regulatory drinking water Health Advisory or any regulatory standard for lithium in public drinking water supplies. Neither has the FDA established a standard for lithium in bottled water at this time. The MDL for lithium and Prestonsburg’s sample results does look like a large number, but as stated before, the MDL is an estimate of the minimum concentration that the laboratory can measure that is above zero. To put into perspective, as it was in the public notice, parts per trillion (ppt) is comparable to adding 10 drops inside of the Rose Bowl. This is how small the compound can be detected, but the method used by laboratories to detect this small amount of lithium is taken into account a concentration of total lithium, accounting for lithium from all compounds present in the water.
Lithium is a naturally occurring element and may be found at higher concentrations in certain parts of the country, particularly in groundwater sources in arid locations in the Western U.S. where geologic formations contain lithium salts. In various formulations, lithium has numerous commercial uses including as a pharmaceutical drug, an industrial chemical catalyst, a sanitizing agent for swimming pools and hot tubs, and increasingly, as a component of lithium-ion batteries for electronics and electric vehicles. It is also likely present in a variety of foods (such as cereal grains, leafy vegetables, and root crops), but it is not clear which foods may be significant sources of dietary lithium.
If you have any questions concerning the results of the UCMR 5 presented in the public notice, please contact Prestonsburg City’s Utilities Commission Main Office at 606-886-6871.
EPA’s Technical Fact Sheet on Lithium: