A new study has found that children born to mothers who were exposed to higher levels of lithium in tap water showed a moderately increased risk of developing autism spectrum disorder. Experts caution, however, that there is no direct correlation.
According to the US Centers for Disease Control and Prevention, approximately 1 in 36 children are diagnosed with autism spectrum disorder (ASD) annually.
Scientists are still unsure of the exact cause for autism, a developmental disorder. While genetics are a possibility, some scientists have also looked at environmental factors.
Although cases may be increasing, the truth is that they are not on the increase. A study on autism cases in New York-New Jersey found that the prevalence of diagnosis among certain age groups tripled between 2000 and 2016. Similar increases were found in 2021's caseloads, however the CDC believes that more doctors are screening for autism.
Rare earth element Lithium can be found in food and water. It is used in air conditioners, batteries, grease, and in the treatment of some blood disorders and bipolar disorder. According to the US Geological Survey, its levels in drinking water are not controlled.
A new study published in JAMA Pediatrics Monday found that there is a slight association between lithium and autism diagnosis. The researchers believe the levels of lithium in Danish drinking water are similar to those in American water systems.
Researchers compared data from a database of children with psychiatric disorders to determine if there were any ASD cases. They also found information about 43,864 people who didn't have ASD. The researchers measured lithium concentrations in 151 public waterworks serving more than half the Danish population. They also mapped the locations of pregnant women.
A slight increase in ASD diagnosis was seen as lithium levels increased in water. The risk of having ASD diagnosed in children was 24% to 26% higher for those with the highest levels of exposure than people who had the lowest level. The highest level of exposure was associated with a 46% greater risk than the lowest.
Researchers could not determine how much water pregnant women drank. However, they chose Denmark because it has the lowest consumption of bottled water in Europe.
Experts agree that it is important to remember that there has not been any evidence that lithium exposure can cause autism.
Additional research is needed, according to Dr. Beate Ritz (study co-author), who is a professor of neurology at UCLA's David Geffen School of Medical and a professor of epidemiology at UCLA Fielding School of Public Health.
Ritz stated in a press release that any drinking water contaminants could affect the brain's development. To find a similar connection, Ritz stated that additional research in other countries would be needed.
An editorial published with the study explains that the implications of these findings have complex implications for public health policy. The study found that lithium levels in water at concentrations associated with ASD risk have been associated with benefits, such as lower hospitalizations for psychiatric disorders or suicide rates.
Dr. David C. Bellinger is a Harvard Medical School professor of neurology and psychology. He stated that if all of these associations are valid, Solomon's wisdom will be needed to create guidelines for lithium in drinking waters that are maximumly protective for the entire population. It will be difficult to tell causal and spurious associations until the biology of ASD is better understood.
Max Wiznitzer is the director of the Rainbow Autism Center at University Hospitals Rainbow Babies and Children's Hospital Cleveland. He points out other research that has looked into the effects of lithium on pregnant women who are taking it for mental disorders. These studies, which examine people who are exposed to higher levels of lithium than is found in drinking water, do not prove that there is an association with autism spectrum disorder.
Wiznitzer, who wasn't involved in the research, said that although it was an intriguing association, causation has not been proven. "We need to find a plausible and biologically plausible mechanism that small amounts of lithium in water can cause this. However, pharmacologic dosing lithium in women with bipolar disorder is not reported to increase the risk of ASD.
Another study has also shown a connection between ASD, environmental exposures to pesticides, pollution, and phthalates. However, none of them point to these environmental factors as the direct cause of ASD.
Wiznitzer stated that it is difficult to prove a link between environmental exposures and ASD. Wiznitzer said that research has shown that ASD is more common in children who have been exposed to high levels of air pollution.
Wiznitzer said, "We are constantly bombarded by a variety of environment stressors in every day life. These stressors are all around us and we have to learn how to safely navigate them. This is not a high priority.