Fluoride added to drinking water is poisonous to the brains of growing children and the greater the exposure, the lower the IQ, concludes the first major review of all available evidence.
The study, jointly carried out by the Harvard School of Public Health and China Medical University in Senyang, China, discovered that children in high-fluoride areas have significantly lower IQ scores than those living in areas with low levels of fluoride (http://dx.doi.org/10.1289/3hp/1104912).
The Chinese-Harvard team studied and number-crunched the combined data from 27 studies, including research on Chinese populations, examining the effects of fluoride exposure from water and coal-burning on the brain development of children, as determined through a number of intelligence-quotient tests.
In studies looking at exposure to fluoride from drinking water only, the Harvard review showed that the greater the exposure, the lower the IQ test scores.
Although the average difference in IQ between children exposed and those not exposed was small-just 0.45 lower in total IQ score-this tiny decrease may have huge effects on two types of children: those with high intelligence; and those who are borderline for educational challenges such as learning difficulties, attention-deficit/hyperactivity disorder (ADHD) and autism.
Chinese children are potentially exposed to far higher levels than the majority of UK or US children. In 2008, the Chinese Ministry of Health reported that 'fluorosis', or fluoride overdose causing mottled teeth, is wide-spread in 28 provinces of the country among its 92 million residents.
Nevertheless, as this latest research demonstrates, subtle effects on the brain are seen with far lower levels. The Harvard researchers noted that other 'neurotoxins' like lead and mercury can cause harm when they reach blood levels in children of just 10 nmol/L. Yet, current allowable levels of fluoride in water in the US and UK lead to blood levels that are 1000 times higher than that.
In the Chinese studies, even low levels of exposure to fluoride in the water (0.24 to 2.84 mg/ L)-the amount of exposure deemed safe in the US and UK-had significant negative effects on a child's intelligence (J Haz Mat, 2011; 186: 1942-6).
Fluoride appears to target the hippocampus-the part of the brain involved with learning and memory. A US National Research Council (NRC) study showed that when neurons from the hippocampus of laboratory rats were placed in a test tube and exposed to various concentrations of sodium fluoride, the animals developed evidence of toxicity.
Fluoride can also alter the layout of the brain; rats allowed to consume up to half the acceptable levels of fluoride in water for a year showed actual changes in the shape of the brain as well as increased amounts of aluminium in brain tissue (Brain Res, 1998; 784: 284-98).
These latest results show that exposure to fluoride can harm early brain development at levels far lower than those that cause harm in adults (Am J Ind Med, 1982; 3: 227-36).
Most of the Chinese studies were made possible because of a natural geological phenomenon in many rural parts of China, making fluoride a natural contaminant in drinking water in some areas, but not in others despite their close proximity. This offers researchers a ready-made opportunity to study the different IQs of populations that are similar in every way except for the water they drink.
Furthermore, unlike most industrialized countries where fluoride levels are usually no higher than 1 mg/L of water, fluoride levels in these rural Chinese communities can be substantially higher-as much as 11 mg/L.
This kind of extremely high exposure enables problems to show up in high relief.
The Harvard study's revelations coincide with recent announcements by the US Department of Health and Human Services (DHHS) to lower levels of permitted fluoride in the water by nearly half following a major 2006 review of the potential effects on intelligence by the NRC (www.nap.edu/openbook.php?record_id=11571&page=205). The DHHS revealed that it intends to lower levels of fluoride in drinking water to a maximum amount of 0.7 mg/L, which is down from the current recommendations for a ceiling of 1.2 mg/L. The Environmental Protection Agency (EPA) is also reviewing the current maximum levels of fluoride allowed, which currently stand at 4 mg/L.
This represents a major volte-face for these departments, which have consistently maintained that fluoride in water at the recommended levels is not only safe, but highly beneficial for preventing tooth decay.
Although this is the most thorough study of the effect of fluoride on IQ to date, it's already well known that fluoride can cross the placenta during pregnancy and be ingested by the fetus. Since the developing brain is far more susceptible to injury than a brain that is fully mature, the concern is that fluoride exposure at early ages could cause permanent damage.
The Harvard study is all the more damning because it follows in the wake of the NRC's report warning that even the beneficial effects of fluoride in preventing tooth decay are incompletely documented. This latest research urges organizations like the World Health Organization and other national agencies, which have long focused on the so-called benefits of fluoride, to start considering that it can be harmful too.
Fluoridation: coming soon to you
The UK has a more modest maximum permitted level of fluoride in drinking water-1.5 mg/L-than the US, according to the Drinking Water Inspectorate (DWI). Nevertheless, at this time the following water authorities have approved mandatory fluoridation:
.Severn Trent Water
.South Staffordshire Water.
However, under the Health and Social Care Act of 2012, the Department of Health will be transferring all responsibility for fluoridation schemes to local authorities on 1 April 2013.
Currently, the DOH is consulting with the public and interested parties on what process local authorities should use for consultations on whether or not to fluoridate water. This process will be open until 27 November 2012.
Bear in mind that this consultation is not debating the pros or cons of fluoridation, but just the way in which the local authorities will decide whether or not to go ahead with it. But you can help to create a more democratic process so that any issues, such as the Harvard research, are factored into the decision.
If you'd like to have your voice heard concerning the process by which fluoridation
will be permitted or banned in your area, let the government know your views by filling out the online questionnaire at http://consultations.dh.gov.uk/fluoridation/fluoridation/ consult_view.
Beware of hidden fluoride
Fluoride isn't just in the water. Virtually every major brand of toothpaste sold in the
UK contains fluoride at approximately 1,000-1,500 parts per million (ppm). Then there's mouthwash, dental floss, vitamins and, in the US, fluoride tablets. Combined with naturally occurring fluoride (in tea, fruits and vegetables) and the fluoride added to water, a child's level of exposure can quickly rocket up to levels more than nine times higher than even the American safe upper limits.
How your children can avoid excess exposure
.Buy non-fluoridated toothpaste like Kingfisher's and Tom's of Maine and those by Boiron and Sarakan. But read labels carefully, as many brands sold in healthfood shops still contain fluoride.
.Buy non-fluoridated dental floss and other products like mouthwash.
.If you do use fluoridated toothpaste, monitor the size of the blob your child uses-keep it pea-sized.
.Ensure that your child spits out all the toothpaste and encourage not swallowing it.
.Ask your dentist to avoid using any products that are fluoridated whenever possible.
.Install a water-filter system, such as a reverse osmosis system, that filters out fluoride.
.Avoid canned foods made in countries with high fluoride levels (like the US).
.Avoid certain drugs that contain fluoride (including Prozac and flucloxacillin).
.Contact your local water authority and ask it to provide you with an analysis of the fluoride content of your water.
October 2012 vol. 23.7