Fluoride in drinking water: Study finds no negative associations for children

Childhood exposure to fluoride through public tap water isn’t associated with any emotional or behavioural issues, nor any negative executive functioning in adolescent years, according to a new study from Australia.

Researchers looked at more than 2,600 children in a longitudinal study that compared children who had spent their lives drinking fluoridated tap water with those who hadn’t, in order to see if exposure to fluoride in drinking water had any negative impacts.

What they found was that fluoridated water wasn’t associated with any decline, and that children who hadn’t been exposed to fluoridated water actually tended to score lower on emotional and executive functioning tests.

Fluoride is a substance that we’re familiar with in our toothpastes or at the dentist’s office, where it is used to help prevent tooth decay and make teeth stronger.

This mineral is also naturally occurring in water to varying levels. To create a standard for water quality, many municipalities and regions in the U.S., U.K. and Canada, among others, add fluoride to their water to achieve an optimal level for oral health.

However, enduring misinformation around fluoride has led to fears that fluoridated water could be a health risk of some kind.

This new study, published Sunday in the Journal of Dental Research, joins ample evidence suggesting those fears are unfounded.

“Water fluoridation is unquestionably effective in preventing dental (problems), and this study is an important addition to the body of literature documenting the safety of water fluoridation,” Brian O’Connell, president of the International Association for Dental Research (IADR) and dean of the faculty of health sciences at Trinity College in Ireland, said in a press release. “The IADR recently reaffirmed its support for water fluoridation as this public health measure has a high benefit/cost ratio and benefits deprived communities the most, thus reducing health inequalities.”

In this new study, researchers looked at data from Australia’s National Child Oral Health Study, which was originally run from 2012 to 2014. This study took a cross-sectional look at the child population aged 5-14 in Australia to examine how oral health varied by social characteristics.

Researchers looked primarily at two groups: children who had been exposed to fluoridated water for all or most of their lives, and those who had little or no exposure to fluoridated water across the study period.

Fluoride exposure levels from birth to the age of five were estimated based on participants’ postal codes and known tap water levels in those areas. This was put together with information gathered at the start of the study period to create a rough “percentage lifetime exposed to fluoridated water”.

When researchers followed up with participants seven to eight years later, they used questionnaires and tests to assess the children’s emotional and behavioural status, as well as their executive functioning.

They then compared the results of those who had spent their lives drinking fluoridated water to those who had not.

Those who had a lower percentage of lifetime exposure to fluoridated water tended to score lower on emotional, behavioural and executive functioning questionnaires, while there was no association found between high percentages of lifetime exposure to fluoridated water and poorer scores on the questionnaires.

Researchers noted that social factors had an impact as well, with low household income among other attributes associated with lower emotional, behavioural and executive functioning scores.

Overall, they concluded that there was no sign that exposure to fluoridated water in the early years of childhood contributed to problems in childhood development.

Australia recommends a fluoridation range of 0.6-1.1 milligrams per litre, with the Australian Drinking Water Guidelines allowing for a maximum of up to 1.5 mg/L.

In Canada, the optimal level of fluoride in our water is 0.7 mg/L, or 0.7 parts per million. These type of calculations assume that residents are also getting fluoride through their toothpaste or mouthwashes.

Like many substances we ingest daily, including salt and oxygen, fluoride can be toxic in large enough doses, but despite studies and careful guidelines, some are still concerned about its presence in water supplies.

This misinformation can have real consequences: a small community in the U.S. was recently shocked to learn that an official in the water department had lowered the fluoride levels without notice, a change that was discovered only after parents began noticing more cavities among their children.

The water and wastewater superintendent of Richmond, Vt., claimed he made the decision because he believed the levels were too high, adding that he doesn’t trust fluoride additives sourced from China, an opinion experts say is not based in fact.

The community has since voted to return the water to full fluoridation.