Claim

“Harvard Study Confirms: Fluoride Lowers Children’s IQ”

detail

Factually inaccurate: A Harvard University study did not confirm that fluoride lowers a child’s IQ. Although this study established a correlation between fluoride levels and children’s IQ, it did not prove that fluoride caused the observed differences in IQ scores.
inadequate support: There is currently no evidence that the levels of fluoride used in community water programs cause cognitive or other serious health problems.

key take away

Fluoride is an element that has been shown to strengthen tooth enamel. Fluoride occurs naturally in water, but is generally too low in amounts to provide any health benefits. Fluoride is added to tap water. Very high levels of fluoride can be toxic to humans, but the concentrations used in fluoridating tap water are much lower and have not been associated with adverse health effects.

Full claim: “Harvard Study Confirms: Fluoride Lowers Children’s IQ”

Tooth decay is the most common preventable childhood disease. According to a 2018 report from the US National Center for Health Statistics, in 2015 and 2016, 45.8% of the US population, including 21.4% of children ages 2-5 and 50.5% of children ages 6-11 are estimated to suffer from tooth decay.

Fluoride has been shown to prevent tooth decay by strengthening tooth enamel. Although this element occurs naturally in food and water, its amounts are generally too low to provide any health benefits. Fluoride is added to community drinking water as a public health measure. In 2013, the US Centers for Disease Control and Prevention (CDC) recognized community water fluoridation as one of his 10 greatest public health achievements of the 20th century.

Late September 2022 Facebook post and multiple tweets by outlet Herbs, Health, and Happiness (see example) here When here) claimed that a study from Harvard University confirmed that fluoride in water lowers children’s intelligence quotient (IQ). This claim is inaccurate, as explained below. This is because the cited studies do not prove that fluoride is responsible for the observed differences in IQ scores. This review also analyzes current scientific evidence regarding the safety and efficacy of water fluoridation.

What did the “Harvard study” show?

Posts claiming that water fluoridation lowers children’s IQs often cite a meta-analysis published in 2012. Environmental health perspective It was co-authored by four researchers, the first to be affiliated with the Harvard School of Public Health.^[1]The authors analyzed 27 epidemiological studies that correlated fluoride levels in different areas with the IQ of children living in those areas and found that “children in high-fluoride areas lived in low-fluoride areas. They have significantly lower IQ scores than their children.”

But contrary to what the post claimed, the analysis only showed that fluoride levels correlated with lower IQ scores. As Health Feedback explained in his 2019 review, it was not proven that the observed differences were caused by fluoride. The authors of the analysis also explained that: [we] Reviews are flawed, and in some cases quite severely flawed, limiting the conclusions that can be drawn. ”

Brittany Seymour, assistant professor of oral health policy and epidemiology at Harvard Dental School, pointed out some of these limitations in a short video released by Harvard Dental School in 2015. NHMRC) cited the same limitation for the effects of water fluoridation on human health in its 2016 evidence review.

First, most of the studies analyzed were from China. As the authors of the analysis acknowledged, many areas of China naturally have “high fluoride concentrations well above 1 mg/L.” This means that the results of these studies cannot be generalized to the United States. In the United States, the Public Health Service recommends a fluoride concentration of 0.7 mg/L (milligrams per liter) in community drinking water.

Second, the NHMRC noted that many of these studies were “potential factors such as exposure to lead and arsenic, iodine deficiency, socioeconomic status, parental education, and nutritional status” that may also affect IQ. did not measure significant confounding factors.” Confounders are variables outside the study that also influence the measured outcome. Such factors can mask relationships between variables and outcomes, or falsely imply relationships between the two when in fact they are not. Failure to account for confounding factors that may affect a child’s her IQ may therefore lead to erroneous conclusions about the potential role of fluoride in the observed differences in IQ scores.

Based on these limitations, the NHMRC concluded, “Overall, this is not convincing and robust evidence for an association between fluoride in drinking water and lower IQ in children.”

A recent prospective study conducted by McPherson and others. New Zealand found no difference in IQ among children living in areas with and without fluoridated tap water^[2]The design of this study makes its results much more reliable than those from a meta-analysis. Assessing IQ scores, McPherson and others. A consistent IQ test was used for all individuals participating in the study, and IQ was measured multiple times during 38 years of follow-up. The study also took into account several potential confounders, including gender, socioeconomic status, breastfeeding, birth weight and education.

Is water fluoridation associated with adverse health effects?

Misinformation persists linking fluoridation of water and dental products with multiple health problems, including hormonal problems, neurological damage and even cancer.^[3]Most of these claims are based on misrepresented studies, flawed evidence, and experimental results that cannot be extrapolated to humans.

For example, laboratory and animal studies have shown that fluoride can be potentially toxic at high levels.^[4-6]However, the concentrations used in these experiments ranged from 7-fold to over 170-fold higher than those in fluoridated drinking water and are therefore independent of tap water fluoridation.

It is important to remember that any substance, even water, can be toxic in too much quantity. However, as described in Health Feedback (here, here, here) and elsewhere (here, here), current evidence suggests that the amount of fluoride in water and dental products such as toothpaste and mouthwash is toxic. The American Cancer Society and National Cancer Institute evidence summaries also show no clear link between fluoride levels and cancer risk.

Health authorities, including the World Health Organization, excess Fluoride levels can have negative health effects. However, these risks are generally associated with much higher fluoride levels than those added to water. (above) It is prevalent in regions of the world.^[7]The condition is caused by fluoride build-up in bones and major joints, causing severe pain and stiffness. However, as the U.S. Human Health Service explained in a 2004 response to a request regarding this condition, skeletal fluorosis is extremely rare in the United States.

One of the risks associated with excess fluoride in the United States is the development of dental fluorosis, which affects the appearance of tooth enamel. According to the American Dental Association, fluorosis only occurs when teeth are forming under the gums, generally under the age of eight, and only if children consume too much fluoride over a long period of time. According to the 2011-2016 US National Health and Nutrition Survey, the majority of cases of fluorosis are very mild or mild and do not affect dental health.

What is the scientific consensus on water fluoridation?

Studies have shown that community water fluoridation programs are safe and effective in preventing tooth decay^[2,8-10]However, much of the evidence is old and of poor quality, and new, high-quality studies are needed to better assess the benefits and risks of fluoridation of water and dental products over time.^[11].

Fluoride in tap water has not been shown to lower children’s IQ scores or cause the health problems perceived by opponents of fluoridation, despite the need for better-quality research. The fact remains. Based on the lack of evidence showing observed benefits and harmful effects, the International Dental Research Association, the American Dental Association, the American Public Health Association, and the American Academy of Pediatrics recommend fluoridating community water as a safe and effective method. I support additions. Prevention of tooth decay.

Current recommendations for fluoride levels in tap water are intended to ensure oral health benefits while minimizing the risk of dental fluorosis. In 2015, the U.S. Public Health Service lowered the recommended level of fluoride from the 0.7-1.2 mg/L range to a concentration of 0.7 mg/L, given the increased use of .[11]This recommendation is non-binding and local governments can decide whether or not to fluoridate their water supplies.

Additionally, the Safe Drinking Water Act of 1974 authorized the US Environmental Protection Agency (EPA) to establish minimum standards for fluoride in drinking water. The EPA recommends that fluoride levels not exceed 2.0 mg/L, and has set an enforceable maximum of 4.0 mg/L.

Conclusion

The claim that a Harvard study showed that water fluoridation lowers a child’s IQ is inaccurate. The cited study only established a correlation between fluoride levels and a child’s IQ score, which alone is insufficient to prove that fluoride lowers IQ. Similarly, other claims that link water fluoridation to various cognitive, neurological, and hormonal problems lack scientific evidence to support them. Although long-term, high-quality studies are needed, current evidence indicates that water fluoridation is a safe and effective means of improving oral health.

References