According to a recent study by a UCLA health researcher, pregnant women whose household tap water had high levels of lithium had a slightly increased chance of their children being diagnosed with an autism spectrum disorder.
The study, published April 3 in JAMA Pediatrics, is believed to be the first to identify naturally occurring lithium in drinking water as a potential environmental risk factor for autism.
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“Any drinking water contaminant that can affect the developing human brain deserves close scrutiny,” said study lead author Beat Ritz, MD, PhD, professor of neurology at the David Geffen School of Medicine at UCLA and professor of epidemiology and environmental health at UCLA. Fielding School of Public Health. “In the future, anthropogenic sources of lithium in water may become more widespread because of lithium battery use and disposal in landfills for potential groundwater pollution. The results of our study are based on high-quality Danish data but need to be replicated in other populations and regions of the world.”
Because of lithium’s mood-stabilizing effects, some lithium compounds have long been used as treatments for depression and bipolar disorders. However, there is debate about whether mothers can safely take lithium during pregnancy because it is associated with a higher risk of miscarriage and heart anomalies or defects in newborns.
Ritz, whose research focuses on how environmental exposures affect neurodevelopmental disorders and neurodegenerative diseases, said she decided to examine the potential link between lithium and autism risk after discovering that there was little research in humans on how lithium affects brain growth and development. Still, he found that some experimental research indicated that lithium, which is one of many naturally occurring metals often found in water, may affect important molecular pathways involved in neurodevelopment and autism.
Zeyan Liew, PhD, MPH, the study’s first author and assistant professor of epidemiology at the Yale University School of Public Health, added that the study was important because previous research findings using high-quality medical registry data from Denmark have shown. Chronic and low-dose lithium intake from alcoholism may affect the incidence of adult-onset neuropsychiatric disorders. However, no studies have been conducted to assess whether lithium from drinking water by pregnant women affects the neurodevelopment of their babies.
Ritz and Liu worked with Danish researchers who analyzed lithium levels in 151 public waterworks in Denmark, which represent the water supply for half the country’s population. To identify which waterworks supplied the mother’s home during pregnancy, the researchers used address information from Denmark’s comprehensive civil registry system. Using a nationwide database of patients with psychiatric disorders, researchers identified children born 1997-2013, and found 12,799 children with autism compared to 63,681 children without an autism diagnosis. The researchers also controlled for maternal characteristics, some socioeconomic factors and air pollution exposure, all of which have been linked to an increased risk of autism in children.
As lithium levels increased, the risk of an autism diagnosis increased, the researchers reported. Compared to the lowest quartile of recorded lithium levels – in other words, those in the 25th percentile – lithium levels in the second and third quartiles were associated with a 24-26% higher risk of autism. In the highest quartile, the risk was 46% higher than in the lowest quartile.
The researchers found a similar association between increased levels of lithium and a higher risk of autism diagnosis when the data were broken down by subtype of the disorder. They also found that the association between lithium levels and autism risk was slightly stronger for those living in urban areas than in small towns and rural areas.
In addition to Denmark’s extensive citizen databases that have proven to be valuable resources for public health researchers, several other factors made Denmark ideal for this study. Denmark’s bottled water consumption is among the lowest in Europe, meaning that Danes are largely dependent on tap water. The country also has a robust system for measuring trace metals and other pollutants in their water supply. Ritz said lithium levels in Denmark’s water, compared to other countries, are likely in the low to medium range.
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