Consuming lithium-contaminated tap water during pregnancy could be associated with an increased risk of newborn autism development, according to a new study from the University of California, Los Angeles.
By cross-checking lithium levels in Danish public waterworks with the country’s extensive civil data on pregnancy and psychiatric disorders, the researchers found that as lithium concentrations increased, so too did autism diagnosis.
Compared to the lowest quartile of recorded lithium concentrations — those in the 25th percentile — those in the second and third quartiles were linked to a 24 to 26 percent increase in autism risk, per the study published on Monday in JAMA Pediatrics.
For those levels in the highest quartile, that risk was 46 percent higher in comparison to the lowest quartile, the authors found.
“Any drinking water contaminants that may affect the developing human brain deserve intense scrutiny,” senior author Beate Ritz, a professor of neurology at UCLA’s David Geffen School of Medicine, said in a statement.
While lithium’s mood-stabilizing effects have made it a go-to treatment option for depression and bipolar disorders, scientists have long debated whether pregnant individuals can safely ingest the metal, Ritz and her colleagues explained.
Increasing evidence, they noted, has linked lithium to a higher risk of miscarriage, as well as cardiac anomalies and defects in newborns.
Ritz, who focuses on how environmental exposures influence neurodevelopment disorders, said she decided to explore a possible connection between lithium and autism risk after finding little research on the subject.
She said she had seen, however, some experimental studies indicating that lithium — a naturally occurring metal often found in water — could influence a key molecular pathway involved in neurodevelopment and autism.
Ritz and first author Zeyan Liew, an assistant professor of epidemiology at Yale University, worked with Danish researchers to comb through lithium levels in 151 public waterworks in Denmark — representing about half of the country’s population.
To ascertain which utilities supplied water to the homes of pregnant individuals, they turned to Denmark’s comprehensive civil registry system.
Probing a nationwide database of patients with psychiatric disorders, they identified 12,799 children born between 1997 and 2013 who had an autism diagnosis, compared with 63,681 children who did not.
They also said they controlled for other factors that could be linked to increased risk of autism, such as socioeconomics and air pollution exposures.
As lithium levels increased in the tap water consumed by pregnant individuals, so too did the risk of autism diagnosis in their newborns, according to the study.
The authors also observed that the association between lithium levels and autism risk was slightly stronger for those living in urban areas than those in rural regions or small towns.
Using data from Denmark gave the scientists access to high-quality medical registry information that had already linked the ingestion of chronic low-dose lithium to adult psychiatric disorders, Liew explained.
The country was also an ideal test case because its consumption of bottled water ranks among the lowest in Europe — meaning Danes predominantly rely on tap water, according to the authors.
Denmark, which tends to have low to moderate levels of lithium in comparison to others, has a robust system for tracing metals in its water supplies, Ritz added.
While emphasizing the high-quality nature of their data, Ritz recognized the importance of replicating the study in other populations around the world.
This is particularly important as the footprint of lithium batteries — key components in in electric vehicles, energy storage systems, toys and electronics — becomes ubiquitous.
“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,” Ritz said.
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