Last summer's droughts in France heightened worries about access to drinking water. While groundwater levels remain critically low, another concern is the quality of the water. A recent report by the ANSES (The French Agency for Food, Environmental and Occupational Health & Safety) highlighted the presence of 54 explosive residues, a solvent called 1,4-dioxane, and 157 pesticides and pesticide metabolites in French drinking water. One particularly troubling finding is the frequent occurrence of the chlorothalonil metabolite R471811, found in over half of the samples and exceeding water quality limits in one-third of cases. It's important to note that the European Union banned chlorothalonil in 2019 due to its potential carcinogenic properties.

A recent study conducted by UCLA Health highlights concern for pregnant women regarding the quality of the water they consume during pregnancy and its potential impact on their unborn children. The study examined samples from 151 public water distribution networks in Denmark and collected data from 50,000 children. The researchers found a statistical correlation suggesting that pregnant women who consumed tap water with higher concentrations of lithium had an increased risk of their children being diagnosed with autism spectrum disorder. The children of mothers with the highest exposure to lithium through drinking water had up to a 46% higher risk of autism spectrum disorder. These findings raise questions about the potential extent of a similar phenomenon in France and call for further investigation.

While lithium is not considered essential for living organisms, it has been suggested to have beneficial effects on the brain and aging in humans. Various studies have found a reverse correlation between lithium concentrations in drinking water and the risk of suicide. Which means that long-term exposure to low levels of lithium in drinking water may have anti-suicidal effects. However, there are controversial reports on the impact of lithium concentrations on humans, and more research is needed to understand its effects

Despite its potential benefits, high levels of lithium can be toxic to the human body. Even therapeutic doses of lithium can cause adverse side effects, including reduced urinary concentrating ability, because of nephrotoxicity, hypothyroidism, hyperparathyroidism, and weight gain. Overdoses of lithium can also lead to neurological, psychiatric, cardiovascular, and gastrointestinal side effects. High lithium levels in water due to pollution from lithium batteries have been found to be toxic to cardiomyocytes, affecting cell capability, proliferation, and promoting cell apoptosis. These effects are believed to be mediated by the regulation of glycogen synthase kinase 3 beta (GSK3β), an enzyme associated with mood disorders, bipolar disorder, depression, and schizophrenia

The median concentrations of lithium in the Danish water samples ranged from 0.6 μg/L to 30.7 μg/L depending on the region. In France, lithium concentrations of tap water range from 0.1 μg/L to 171 μg/L (average 4,6 µg(Li)/L) depending on the region, according to The French National Institute for Industrial Environment and Risks (INERIS). The increasing pollution of water worldwide is attributed to factors such as improper disposal of disposable batteries and the extraction of underground lithium. Pesticides and lithium join the already extensive list of pollutants in global and French waters, including nitrates, various endocrine disruptors, and pharmaceutical releases.

There is no regulation for lithium in tap wate in the EU. Also, the World Health Organization (WHO) and other health governing bodies have not provided any guidelines or recommendations regarding the acceptable maximum amount of lithium (Li) in drinking water for safe consumption.