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Link Between Lithium Levels in Drinking Water and Autism Risk Identified

A person filling a green glass with water from a tap.
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A new study in Denmark has reported that pregnant women with high levels of lithium in household tap water may have a moderately higher risk of their children being diagnosed with autism. The research is published in JAMA Pediatrics.

Questioning lithium’s safety in pregnancy

Lithium is a metal element that, among several others, is found naturally occurring in water. Chemical compounds containing lithium have been used for decades as a mood stabilizer, helping to treat psychiatric conditions such as bipolar disorder and depression. Lithium’s safety for use during pregnancy has been subject to debate however, with increasing evidence suggesting it may be associated with increased risk of miscarriage or birth defects including cardiac anomalies.

Little research has been conducted in terms of the possible effects of lithium on brain growth and development. This inspired Dr. Beate Ritz, senior author of the current study and professor of epidemiology and environmental health and neurology at the University of California Los Angeles (UCLA), to shift her research focus from studying environmental factors in neurodevelopmental and neurodegenerative conditions to investigating how lithium may be associated with autism risk.

Previous research using Danish medical registry data has indicated a link between chronic and low-dose lithium ingestion from drinking water and neuropsychiatric disorders in adulthood. However, the current study is believed to be the first to identify naturally occurring lithium in tap water as a possible environmental risk factor for autism.

High lithium levels may increase autism risk

Ritz and colleagues analyzed data extracted from Denmark, where lithium levels were measured in 151 public waterworks, and determined which waterworks supplied the homes of pregnant women using a comprehensive civil registry system. Additionally, the researchers used a national database to identify children born between 1997–2013 – comparing 12,799 autistic children and 63,681 non-autistic children. These data were controlled for factors that have been linked to increased risk of autism, such as particular maternal characteristics, socioeconomic factors and air pollution exposure.

The findings revealed that as lithium levels in household tap water increased, the risk of autism diagnosis also increased. There was a 24–26% higher risk of autism diagnosis in the second and third quartiles of lithium levels in tap water compared to the first (lowest) quartile. This rose to a 46% higher risk in the highest quartile compared to the lowest.

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Furthermore, the researchers found that this association between lithium levels and autism was somewhat stronger in urban areas compared to rural areas and small towns.

Additional investigation required

“The results of our study are based on high-quality Danish data but need to be replicated in other populations and areas of the world,” added Ritz. Together, Denmark’s relatively low consumption of bottled water, comprehensive civil databases and comprehensive monitoring of metals and contaminants in the water supply make it a good source of information for these types of studies. However, additional research worldwide is required to see if these findings are translatable to other areas and populations.

“Any drinking water contaminants that may affect the developing human brain deserve intense scrutiny,” said Ritz. “In the future, anthropogenic sources of lithium in water may become more widespread because of lithium battery use and disposal in landfills with the potential for groundwater contamination.”

Reference: Liew Z, Meng Q, Yan Q, et al. Association between estimated geocoded residential maternal exposure to lithium in drinking water and risk for autism spectrum disorder in offspring in Denmark. JAMA Pediatrics. 2023. doi: 10.1001/jamapediatrics.2023.0346

This article is a rework of a press release issued by UCLA Fielding School of Public Health. Material has been edited for length and content.

Meet the Author
Sarah Whelan, PhD
Sarah Whelan, PhD
Science Writer