NEW YORK, Oct 2, (AP): A federal judge has ordered the US Environmental Protection Agency to regulate fluoride in drinking water further because high levels could pose a risk to the intellectual development of children. US District Judge Edward Chen cautioned that it’s not certain that the amount of fluoride typically added to water is causing lower IQ in kids, but he concluded that mounting research points to an unreasonable risk that it could be. He ordered the EPA to take steps to lower that risk but didn’t say what those measures should be.

It’s the first time a federal judge has decided about the neurodevelopmental risks to children of the recommended US water fluoride level, said Ashley Malin, a University of Florida researcher who has studied the effect of higher fluoride levels in pregnant women. She called it “the most historic ruling in the US fluoridation debate that we’ve ever seen.” The judge’s ruling is another striking dissent to a practice that has been hailed as one of the greatest public health achievements of the last century. Fluoride strengthens teeth and reduces cavities by replacing minerals lost during normal wear and tear, according to the US Centers for Disease Control and Prevention. Last month, a federal agency determined “with moderate confidence” that there is a link between higher levels of fluoride exposure and lower IQ in kids. The National Toxicology Program based its conclusion on studies involving fluoride levels at about twice the recommended limit for drinking water.

The EPA - a defendant in the lawsuit - argued that it wasn’t clear what impact fluoride exposure might have at lower levels. However the agency is required to make sure there is a margin between the hazard level and exposure level. And “if there is an insufficient margin, then the chemical poses a risk,” Chen wrote in his 80-page ruling Tuesday. “Simply put, the risk to health at exposure levels in United States drinking water is sufficiently high to trigger a regulatory response by the EPA” under federal law, he wrote. An EPA spokesperson, Jeff Landis, said the agency was reviewing the decision but offered no further comment. In 1950, federal officials endorsed water fluoridation to prevent tooth decay, and they continued to promote it even after fluoride toothpaste brands hit the market several years later. Fluoride can come from several sources, but drinking water is the main source for Americans, researchers say. Nearly two-thirds of the U.S. population currently gets fluoridated drinking water, according to CDC data.