A new study from the University of Kent has found that Britons who live in areas with higher water fluoride levels are significantly more likely to develop thyroid problems.
The debate has long raged on about whether adding fluoride to drinking water is a boost or a bane. The US Centers for Disease Control has dubbed water fluoridation one of the ten greatest public health achievements of the 20th century, due to its cavity-reducing properties and measurable improvement of the nation's dental health. (Numerous 15-year studies have shown that drinking fluoridated water reduces tooth decay in children by an average of about 60 percent.)
“...found that patients in areas with high levels of fluoride in the water (equal to or greater than 0.3 milligrams per liter) are 30 percent more likely to have underactive thyroids...”
But countless groups have spoken out in opposition to the practice since fluoridation became common practice in the 1940s. Citizens and advocacy groups alike have questioned not only whether fluoride is effective and safe (fluoride poisoning can result in weakened bones, and adverse reactions such as nausea, vomiting, and diarrhea), but also whether it's ethical to medicate the water supply of entire nations. Though water fluoridation continues in many countries such as the US, the United Kingdom, Ireland, Canada, and Australia, many others—including Germany, Sweden, Japan, the Netherlands, and Finland—have discontinued it.
A new study will add fuel to the ongoing fire of controversy surrounding the practice. Researchers at the University of Kent analyzed data from nearly 8,000 general practitioners' offices in the UK—accounting for 98 percent of practices. They found that patients in areas with high levels of fluoride in the water (equal to or greater than 0.3 milligrams per liter) are 30 percent more likely to have underactive thyroids. According to the research team, up to 15,000 British citizens could be experiencing hypothyroidism due to fluoride exposure. Common symptoms of an underactive thyroid include weight gain, depression, low body temperature, and fatigue.
The key to a healthy thyroid is iodine, which is generally absorbed through the blood and stored and regulated by the body in the thyroid gland. (Iodine-rich food sources include seafood, dairy products, eggs, seaweed, and iodized salt.) But because fluoride is more electronegative than iodine, it displaces it in the body, disrupting thyroid function and subsequently impacting hormone levels that keep metabolism in check. Numerous studies (including one from just last year) have previously confirmed fluoride's ability to promote and exacerbate iodine deficiency, but the University of Kent study is one of the first to identify causation.