Researchers found no link between fluoride exposure and adverse health effects in a study published in Neurotoxicity Research, the National Toxicology Program, or NTP, announced in April.

The study, sponsored by the NTP, headquartered at the National Institute of Environmental Health Sciences of the National Institutes of Health, reported no observed fluoride exposure-related differences in motor, sensory or learning and memory performance in rats. Researchers also found no exposure-related pathology in the heart, liver, kidney, testes, seminal vesicles or epididymides.

The study comes after a 2016 NTP systematic review that found a “low to moderate level of evidence” that supported adverse effects on learning and memory in animals exposed to fluoride in food and water. However, many of the studies examined as part of the review included exposure to fluoride at levels higher than 0.7 parts per million, the recommended level for community water fluoridation in the U.S.

The study published earlier this year, which is available to view online, “was designed to address issues identified” in the 2016 systematic review, researchers said. For the study, rats were exposed to fluoride in their diets and drinking water designed to simulate human fluoride exposure.  Fluoride in drinking water was examined at three levels with the highest being equal to human consumption of 4 mg/L (ppm) which is the U.S. EPA’s maximum level for naturally occurring fluoride in water and more than five times the amount recommended for community water fluoridation (0.7 mg/L).

“The ADA supports ongoing research on the safety and effectiveness of community water fluoridation,” said Dr. Bonita Neighbors, chair of the ADA National Fluoridation Advisory Committee. “This study by respected researchers at NTP strengthens the scientific base demonstrating the safety of water fluoridation.”

In addition to the NTP study, two new major reports have been recently published highlighting the safety of fluoridation as a public health measure.

Public Health England, on behalf of the country’s secretary of state for health and social care, released a report in March that concluded, “Water fluoridation is an effective and safe public health measure to reduce the prevalence and severity of dental caries, and reduce dental health inequalities.”

In April, the Food Safety Authority of Ireland released a report from its Scientific Committee, which evaluated the consumption of fluoride from food and drink intake, including tap water. The report concluded that “based on scientific evidence, there is no safety concern for children and adults living in Ireland from exposure to fluoride through intake of foods and beverages.”

The ADA endorses community water fluoridation as a safe, beneficial, cost-effective and socially equitable public health measure for preventing dental caries in children and adults. For more information, visit

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