Fluoride is in the news again. And not for very good reasons. In reviewing information published this month Scientists found evidence that higher levels of fluoride exposure are associated with lower IQ in infants and young children.
Historically, fluoride has been added to water to strengthen our tooth enamel. which helps prevent tooth decay It is well known that better childhood dental health reduces sick days from school. As a result, dental procedures are less expensive. and may even reduce the risk of heart disease and stroke later in life.
But this new research , conducted by scientists from the NIH's National Toxicology Program, suggests that fluoride exposure and the amplification of fluoride in water may be more risky than previously thought. They found that children who were exposed to higher levels of fluoride in the early years of life had significantly lower IQ scores. Specifically, between 1 and 2 points more than children who received low levels of fluoride.
review published in JAMA PediatricsIt's not the only recent study that shades fluoride. A study last May, for example. meet A link between higher fluoride exposure in pregnant women and a greater risk of their children being diagnosed with neurological problems by age 3 has been linked by some scientists. together that has been asked recently Is it necessary to have fluoride in the water to further benefit from fluoride? This is because people in many parts of the world can get fluoride from their toothpaste products.
However, the scientific debate about the pros and cons of fluoride is not one-sided. some scientists have criticize The methodology and interpretation of the latest review, etc., and the study itself were not found. Conclusive evidence Linking lower IQ to low fluoride intake Including the recommended level for US drinking water (0.7 milligrams per liter). Other reviews include: similarly failed To find a link between relatively low fluoride intake and loss of IQ or impaired development (including After introducing the fluoride program–
Some fluoride critics also try to blame fluoride for other health problems. There is much less evidence to support a possible link. Robert F. Kennedy Jr. is in line to head the U.S. Department of Health and Human Services. Under the Trump administration, dispute For example, fluoride is linked to bone cancer. Although most studies do not find it. Important cancer links–
For this Giz Ask, we reached out to experts to share their thoughts on the latest study. The science about fluoride and the potential impacts of this research The following answer has been edited and condensed slightly for clarity.
Jay Kumar
Retired epidemiologist who specialized in dental health and co-author of a Meta-analysis in 2023 regarding the potential effects of fluoride on children.
The finding that high fluoride levels in drinking water in rural areas of China, India, Pakistan and Iran are associated with IQ deficits is not new. The authors cannot assume that the IQ deficit is caused by fluoride in the water. Due to the low quality of education These studies simultaneously measure fluoride in drinking water and children's IQs. For example, it may be that parents with higher IQs have moved out of the region to avoid fluoridated water. tall Because it is known to be more vulnerable to teeth and bones, the absence of higher IQ groups may drive the relationship rather than reverse it. This potential bias is sometimes referred to as “The cart-before-the-horse bias” Additionally, animal and human studies cannot explain how fluoride affects the brain.
We published a study on “Relationship between low fluoride exposure and child intelligence: A meta-analysis related to community water fluoride” In this article, we answer the research question: Fluoride exposure. Do recommended dental practices for preventing tooth decay reduce children's cognitive abilities and IQ scores? A fluoride limit of 0.7 mg/L is recommended for municipal water supplies in the United States.
Our study concludes that fluoride exposure at approximately twice the concentration used to fluoridate community water (less than 1.5 mg/L) is not associated with IQ scores. that is lower in children. However, we emphasize the need for further research to determine whether naturally occurring fluoride in drinking water in excess of 1.5 mg/L causes IQ deficits.
g A recent Australian study Do and colleagues confirm again findings from Canada, New Zealand, and Spain that IQ scores are similar in fluoridated and non-fluoridated areas.
Bruce Lanhere
Epidemiologist from Simon Fraser University, who has study How might fluoride exposure in pregnancy affect the later development of the child?
Fluoride is a reactive chemical that binds strongly to calcium and metals. In 1944, the Journal of the American Dental Association described fluoride as: “Very attractive” for preventing tooth decay But warn of the risks of doping. Today, more than 70% of Americans drink tap water with about 0.7 parts per million (ppm) of fluoride, which is considered “optimal.” Fluoride also contains It's in toothpaste (1,000–1,500 ppm), black tea (1–6 ppm), foods such as sardines and anchovies (2–4 mg/100 grams), some medications (such as Prozac, Lipitor), and insecticide Process the produce like raisins. Over the past 50 years, fluoride consumption has increased. This results in increased tooth fluorosis, which is discoloration or staining of the teeth due to exposure to too much fluoride during development.
What did the study find?
Taylor's team reviewed 74 studies from 10 countries linking fluoride exposure to IQ scores. Although early studies Many are of lower quality. A meta-analysis of high quality research found that A 1 ppm increase in urinary fluoride is associated with a 1.2 point decrease in children's IQ, even at levels below 1.5 ppm. But it has a huge impact on the population. This is especially true for children who are exposed to other toxic chemicals such as lead or air pollution.
Are these findings relevant to fluoridated communities?
Critics argue that no IQ deficits have been found at water fluoride levels less than 1.5 mg/L, but this is misleading. First, no clear threshold has been specified. Second, fluoride in Water is the only source of exposure. And the total amount of fluoride must be considered to assess risk. Urine fluoride, which is a snapshot of overall fluoride content Children's IQ has been shown to decrease significantly at concentrations typically found in fluoridated communities.
For example, a Canadian study found that 25% of pregnant women in areas that received adequate fluoride had urinary fluoride levels above 1 ppm and 5% above 1.5 ppm, although some placed Questions about the reliability of urine fluoride measurement But it's also widely used by epidemiologists to assess exposure to short-lived chemicals like fluoride and arsenic.
Can fluoride prevent tooth decay?
It's time to take a critical look at the benefits of fluoride. 2024 Update of Cochrane Review Little or no benefit from water fluoridation was found in studies conducted after 1975, when fluoride toothpaste became widely available. The protective effect of fluoride on tooth decay is primarily local. It is not a general effect and is not useful until teeth emerge.
Should you be worried?
Public health agencies must reevaluate fluoride guidelines based on new evidence. In the meantime, consider these precautions:
- Pregnant women and young children: Avoid fluoridated water and other sources of fluoride such as black tea.
- Infant formula: Use non-fluoridated water when mixing formula. Breast milk has the least amount of fluoride.
- Children's toothpaste: Use only a rice-sized amount of fluoride toothpaste. and make sure that children won't swallow toothpaste
When following these steps You can minimize your exposure to fluoride during this important developmental period.
Sarah Evans
Assistant Professor of Environmental Medicine and Climate Sciences at the Icahn School of Medicine at Mount Sinai, who studies how people's early life exposures affect behavior and cognition.
It's important to note that no studies have been conducted. Included in the meta-analysis (NTP) conducted in the United States The recommended fluoride concentration in drinking water is 0.7 mg/L, which is more than 50% lower than measured fluoride exposure in most of the communities studied, although by 2023 it will be required. Further studies to examine the effects of low levels of fluoride exposure. Meta-analysis No link was found between fluoride and children's IQ in communities with drinking water levels similar to those in the United States.
until now There have been no studies indicating a risk of harm from the 0.7 mg/L fluoride most commonly found in U.S. drinking water. But an estimated 2.9 million Americans and 180 million people worldwide may be exposed to fluoride levels above WHO guidelines because of high levels of natural fluoride in some areas. Individuals living in these areas may be at greater risk of exposure to levels associated with lower IQs in children in this study. Additionally, the inclusion of fluoride in dental products and treatments. karma Including their natural presence in certain foods and beverages. May lead to exposure higher than daily recommendations. Comprehensive studies that measure individual exposure levels in the U.S. population from all fluoride sources are needed.
Although approximately three-quarters of U.S. tap water contains fluoride, But this practice is not federally mandated and is subject to state or local regulation. Therefore, fluoridation practices vary across the country. For example, 99.9% of Kentuckians get fluoride in their drinking water. That compares to just 16% of New Jersey residents. Individuals interested in knowing the level of fluoride in drinking water should contact their water supplier. If you live in an area with high levels of natural fluoride, and are pregnant or have young children You can reduce your exposure to fluoride through reverse osmosis filtration. Bottled water is not regulated to contain fluoride or other contaminants. and is generally not recommended. If you use water from a public or private well that does not contain fluoride, It is important to practice good dental hygiene by using fluoride toothpaste and mouthwash. and visiting the dentist regularly
The findings from this study are likely to lead to an increase in communities questioning whether to phase out water fluoridation. This is despite some evidence showing that the increase in fluoridated products and improved access to dental care has reduced the demand for fluoridated water. But several studies show a dramatic increase in childhood tooth decay and the need for dental treatments in communities that remove fluoride from drinking water. This suggests that water fluoridation remains an effective and necessary public health intervention.
Meanwhile, a recent meta-analysis by Taylor et al points to negative effects of high levels of fluoride exposure on brain development. It also emphasizes the need for well-designed, long-term studies. It measures individual exposure to fluoride over time. To ascertain whether there is a relationship with IQ or other neurodevelopmental outcomes. remains at the low level experienced by Most Americans The document also emphasizes the need to research practices that reduce the risk of exposure to fluoride above recommended levels in areas with high fluoride levels. Naturally at a high level and re-examining guidelines to increase access to routine dental care.