Lithium salts are used as a mood-stabilizing drug in treating bipolar disorder and depression. Lithium is commonly used in batteries, glass and ceramic glazes, air conditioning, grease and electric cars. It is also used as a sanitizing agent for swimming pools and hot tubs.

People also come in contact with lithium when working with glazes used with ceramics and glass. Lithium has become an important component of batteries and electrodes. It is also used in lubricating greases, continuous casting mould flux slags, welding, pyrotechnics and air purification.

Lithium is likely present in a variety of foods. The main sources are cereals, potatoes, tomatoes, and cabbage, as well as some spices such as nutmeg, coriander seeds, or cumin, though these contribute negligible amounts in many geographic regions. Tea, a common beverage throughout the world, contains varying levels of lithium.

There are differing perspectives on whether lithium is beneficial in small amounts (e.g., a micronutrient). The United States has no current recommended dietary allowance for lithium.

Lithium is not believed to pose a health risk when consumed appropriately. There are some who believe lithium offers mental health benefits.

Adverse human health effects based on exposure at therapeutic doses have been observed in several organs and body systems of treated patients. The types of health effects are consistent with the limited number of available toxicology studies.

• Renal (kidney-related) effects: Lithium pharmaceutical treatment can interfere with the kidney’s ability to concentrate urine, resulting in excessively dilute urine and feelings of thirst. Severe kidney disease may result from long-term treatment at higher doses.
• Neurologic (nervous system) and other effects: Lithium pharmaceutical treatment can cause lethargy, fatigue, weakness, tremor, and cognitive impairment, as well as impairment of endocrine gland function such as the thyroid and parathyroid. Other severe but rarer effects, including developmental effects, have also been associated with lithium therapy.

The U.S. Environmental Protection Agency (EPA) cites side effects from therapeutic doses, including gastrointestinal, neurological, psychiatric, renal and cardiovascular effects; decreased thyroid function; acneiform skin eruptions; benign leukocytosis.

In the EPA's first publicly-released UCMR 5 data, the most frequently observed analyte was lithium. It was detected in 30.5% of systems and above the EPA's health reference level in 22.1% of systems.

Lithium in drinking water is not regulated, but it is listed among the contaminants listed in the Fifth Unregulated Contaminants Monitoring Rule (UCMR 5).

Every five years, EPA uses the UCMR to monitor for the highest priority unregulated drinking water contaminants at public water systems across the United States. Occurrence data collected under the UCMR 5 will be used by EPA as basis for future regulatory determinations and may support additional actions to protect public health.

A 2021 report from the U.S. Geological Survey (USGS) reports lithium is present in private wells and often exceeds the human-health benchmark.

If you are concerned about lithium in your drinking water, you may consider purchasing a home treatment device. However, in order to make a well-informed and cost-effective decision, consider:

• Checking with your water system or consumer confidence report to learn about the amount of total lithium in your water
• Identifying a device that has been independently certified to remove lithium

NSF International, the Water quality Association, Underwriters Laboratories and CSA International all certify home treatment products for removal of contaminants. If you choose to use a home treatment device, it is very important to follow the manufacturer's operation and maintenance instructions carefully in order to make sure the device works properly.

NSF International standards do not currently include lithium, so manufacturers do not have a standard against which to certify.

Lithium has been found in several different brands of bottled water. In fact, bottled water may contain higher levels of lithium than tap water, as it is sometimes drawn from springs known for high mineral content. One American brand of bottled spring water claims that its water contains 500 μg/L of lithium.