Cnn
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A new study has revealed a moderately higher risk of autism spectrum disorders in children born of pregnant people exposed to tap water with higher levels of lithium, but experts warn that this association does not show a direct link between the two.
In the United States, around 1 in 36 children is diagnosed each year with an autism spectrum disorder (TSA), according to data from the Centers for Disease Control and Prevention American.
Scientists still do not know the exact cause of autism, a development disorder. Genetics can be a factor, but some have also examined potential environmental causes.
Cases can be increasing, but this is not clear. A study published this year on cases in the New York-New Jersey region has revealed that autism diagnostic rates tripled among certain age groups between 2000 and 2016. A 2021 report revealed similar increases in cases, but the CDC affirms that the increase in cases is most likely linked to more detection of doctors for the disease.
Lithium is an alkaline metal that can be found naturally in certain foods and groundwater. It is used in batteries, fat and air conditioners, as well as in the treatment of bipolar disorder and certain blood disorders. Its levels in American drinking water are not regulated, according to the US Geological Survey.
A new study, published Monday in the journal Jama Pediatrics, revealed a small association between lithium and the diagnosis of autism in Denmark, where researchers say that the level of lithium in drinking water is similar to that of American water systems.
The researchers checked a database of people with psychiatric disorders for children born between 2000 and 2013 to find information on 8,842 cases of ASD and 43,864 participants who did not have ASD. They then measured the concentration of lithium in 151 public waterworks which served more than half of the Danish population and cartographed where the borders lived in relation.
As the lithium levels in water increased, there was an increased modest risk of a TSA diagnosis. More specifically, compared to people at the lowest level of exposure, those who had the second and third highest exposure during pregnancy had a risk of 24% to 26% higher of TSA diagnosed in children. The group with the highest exposure presented a 46% higher risk than those at the lowest exposure level.
The researchers could not say how much water the speakers were drinking, but they chose Denmark in part because the residents consume some of the lowest quantities of bottled water in Europe.
Experts say that it is important to note that research cannot show that exposure to lithium leads directly to a diagnosis of autism.
A more in-depth study is necessary, said the co-author of the study, Dr. Beate Ritz, professor of neurology at the David Geffen School of Medicine of the UCLA, and professor of epidemiology and environmental health at the UCLA Fielding School of Public Health.
“All drinking water contaminants that can affect the human brain in development deserve a meticulous examination,” Ritz said in a press release. She added that research should be reproduced in other countries to seek a similar connection.
The implications of the results are complex with regard to public health policy, according to an editorial published alongside the study. The levels of lithium in water, at concentrations that the study associated with a potential risk of TSA, were also linked to health benefits such as lower hospitalization rates for psychiatric disorders and suicide.
“If all these associations are valid, Solomon’s wisdom will be necessary to develop directives for lithium in drinking water which protects the entire population as much as possible,” wrote Dr. David C. Bellinger, professor of neurology and psychology at the Harvard Medical School. “Until the basic biology of TSA is better understood, it will be difficult to distinguish causal associations from parasites.”
Dr. Max Wiznitzer, director of the Rainbow Autism Center of the University Hospitals Rainbow Babies and Children’s Hospital of Cleveland, underlines other research on the effects of lithium on pregnant people who take it for mental health disorders. These studies – who look at people exposed to much higher levels than in drinking water – do not show a link with autism spectrum disorder.
“It is an interesting association, but causality is certainly not proven,” said Wiznitzer, which was not involved in the new research. “We must see if there is a viable and biologically plausible mechanism by which a small amount of lithium in the water supply can somehow do it, but it has not been reported that the pharmacological risk of lithium in women with bipolar disorder has not caused an increased risk of TSA.”
Other studies have also suggested links between ASD and environmental exhibitions to things such as pesticides, air pollution and phthalates. But none of them report to any of these factors as a direct cause of the disorder.
A link between environmental exposure and TSA is difficult to prove, Wiznitzer said. Research showing that an increased exposure to air pollution increases the risk of giving birth to a child with TSA, for example, it often wonders if pollution is the determining factor or if it is only populations that live in more polluted areas.
“There is a lot of speculation on environmental factors, but how many of them are really associated because of causality?” Wiznitzer said. “We are bombed with a variety of environmental stressors in our daily life. We must understand how to navigate them essentially in complete safety, and it is probably not the one that is high on our list. ”