A research study conducted by the Canadian research program Maternal-Infant Research on Environmental Chemicals (MIREC) and recently published in the Journal of the American Medical society has raised concerns about the effect of fluoride on the developing brain.
The researchers examined data from 512 mother-child pairs, with children born between 2008 and 2012, recruited from 6 sights in Canada. The researchers compared maternal urinary fluoride levels as well as self-reported maternal daily fluoride intake to the children’s IQ, assessed at ages 3 to 4 years. They found significant interactions between maternal urinary fluoride levels and IQ, but only in male children. A 1-mg/L increase in maternal urinary fluoride levels was associated with a 4.49-point lower IQ score (95% CI, −8.38 to −0.60) in boys, but there was no statistically significant association with IQ scores in girls (95% CI, −2.53 to 7.33). The average increase in urinary fluoride concentration for pregnant women living in a fluoridated vs a non-fluoridated community, was associated with a 1.5-point IQ decrement among boys. For the self-reported data, a 1-mg higher daily intake of fluoride among pregnant women was associated with a 3.66 lower IQ score (95% CI, −7.16 to −0.14) in boys and girls. These results remain significant after controlling for other key exposures such as lead, arsenic, and mercury. The authors concluded that maternal exposure to higher levels of fluoride during pregnancy was associated with lower IQ scores in children aged 3 to 4 years.
The finding that fluoride exposure during brain development is detrimental to IQ is further supported by the results of other studies that examined the relationship between childhood IQ and maternal fluoride exposure. Taken together, the data provide strong evidence for the need to reduce fluoride intake during pregnancy and perhaps in childhood as well. The results also raise the question of whether boys are more vulnerable to the effects of fluoride, especially given boys have higher incidence of developmental brain disorders including ADHD, learning disabilities, and intellectual disabilities. The effects of fluoride exposure throughout infancy, childhood, and adolescence also need to be further examined.
Taking a step back: Why was fluoride added to our water in the first place?
Water fluoridation was introduced in the 1950s to prevent dental caries. Fluoride displaces calcium in the mineral matrix that makes up our tooth enamel which makes it more resistant to damage caused by bacteria and acids that cause tooth decay. Prior to the age of modern dentistry, tooth decay was a major public health crisis. In fact, about three in ten Americans aged 45 or older had none of their natural teeth remaining and the most common cause of WWII draft rejection was due to tooth decay. Given this, it is easy to see why officials were so eager to take steps to improve the dental health of society. In the 1950s, most Americans did not brush their teeth on a daily basis or use fluoridated toothpaste and other dental products. In this environment, supplemental fluoride from water was a potential aid to millions, especially to the dental health of children. Despite surprisingly little quality information about the effectiveness and safety of fluoridated water, fluoridation became an official policy of the U.S. Public Health Service in 1951 and rapidly became widespread. By 1960 water fluoridation reached ~50 million people and by 2006 that number rose to over 61% of the total U.S. population. Initially, the evidence on the effect of fluoride was positive, especially in children. Studies conducted in the 50s and 60s found water fluoridation reduced childhood cavities by 50-60%. Water fluoridation was widely celebrated as a triumph of public health policy. However, most modern studies have found a reduced effect, likely from increased fluoride exposure from other sources. The data overall is also mostly of poor quality and lacks adequate controls for changing rates of sugar and other carbohydrate consumption.
Is water fluoridation still advantageous in the modern environment?
The behaviors of Americans have changed over time and the benefits versus the risks of water fluoridation should be reexamined. While tooth decay remains a common and serious health condition it is no longer a national emergency and there are other safer options that can also take advantage of fluoride’s benefit to our teeth. Access to modern dentistry, daily brushing, sealants, and fluoridated dental care products have allowed millions of American children to grow up with little or no decay, and total tooth loss that was once a common feature of mature adults is now rare. Oral health research continues to progress and new advanced treatments that have the potential to repair damaged teeth rather than filling them are on the horizon. While water fluoridation has certainly played a role in America’s improved oral health, the policies that were initially developed in the 50s were conceived prior to the advent of modern dentistry and oral hygiene.
Although we are still learning about the risk of water fluoridation, the evidence for benefit on oral health is fairly strong amongst children who had no other access to fluoride. However, this no longer represents the majority of America and millions of children are exposed to other significant sources. In fact, in 2012, 68% of adolescents were found to have some level of enamel fluorosis, a condition caused by excess exposure to fluoride. Enamel fluorosis itself causes only cosmetic issues, and has been largely ignored by public health officials. However, given new concerns regarding fluoride’s effect on brain development, the high rate of fluorosis should raise a red flag that the level of fluoride in our water may be too high for the modern environment. That is, if it is even worthwhile in the first place. We now understand that the benefit of fluoride is predominantly due to its action on tooth surfaces. The best protection is provided by constant low levels of fluoride in the saliva after the eruption of teeth from the gums. There is no additional significant benefit of ingested fluoride for our teeth or of fluoride exposure prior to the eruption of our teeth from our gums. There is also no benefit of fluoride exposure during pregnancy for the prevention of tooth decay in offspring. Thus topical products that are not intended for ingestion such as toothpaste, mouthwash, and professionally applied gels, gums, and varnishes should be just as effective. Research has demonstrated that the detrimental effects of fluoride depends upon the total daily ingested dose so products that are not ingested are also likely much safer when used correctly.
The calculus behind the risk benefit analysis that public health officials must use to make decisions in the public interest regarding fluoride is certainly changing. More evidence of harm has come to light yet the argument for the continued need for water fluoridation is bolstered by the fact that many American children do not visit a dentist regularly or follow recommended oral hygiene routines. Because of this, fluoridated water remains the largest source of fluoride for a large portion of our population. However, there are safer, more effective, and flexible methods of improving the dental health of our population. For instance, a national comprehensive school-based dental program would ensure access to proper dental care for all American children, eliminate the need for water fluoridation, and reduce the risk we face from excess fluoride.
What can you do to protect yourself and your children from the risk posed by excess fluoride exposure?
Research has demonstrated the beneficial effect of small but consistent fluoride exposure for our teeth but it has also shown that ingested fluoride may be harmful to the rest of our body, especially the developing brain. The largest source of fluoride ingestion for most Americans is either through intake of fluoridated water or through accidental swallowing of fluoridated dental products. Other sources include air pollution from fluoride-containing coal or phosphate fertilizers, fluoride-containing pesticides, fluorinated pharmaceuticals, and teflon pans. Certain foods may also have significant levels of fluoride including tea leaves, barley, cassava, corn, rice, taro, yams, mechanically deboned chicken, fish protein concentrate, and processed foods made with fluoridated water. Once ingested, more than 70% of fluoride is absorbed into the bloodstream and the majority of this fluoride is absorbed into body tissues, especially in infants. Thus it is important to take steps to limit the ingestion of fluoride, especially in young children.
Despite the importance of preventing ingestion of fluoride in young children, most dental products marketed to children do contain fluoride. Labels for toothpaste contain warnings such as “do not swallow” and advise that “if more than used for brushing is accidentally swallowed, get medical attention or contact a Poison Control Center right away.” They go on to state “to minimize swallowing use a pea sized amount for children under 6” and to “supervise children’s brushing until good habits are established”. In terms of preventing fluoride poisoning, by “good habits” they mean until a child can be trusted not to swallow the toothpaste. However, anyone who has ever even witnessed a young child brush their teeth knows that, even when supervision is provided, preventing a 3 year old from swallowing the sweet bubblegum flavored Sponge Bob promoted paste is impossible. It is also odd that many labels do not specify how much toothpaste should be used for adults. Toothpaste commercials certainly show copious amounts being applied to toothbrushes though. It is irresponsible not to specify a normal amount for brushing when ingestion of “more than used for brushing” is deemed a medical emergency. Furthermore, even if we stipulate that ¼ to 1/2 of a teaspoon is a normal amount to use and we are told ingesting more than that one time is a medical emergency, how can ingesting a “pea sized amount” twice per day every day as a child be non-harmful? The answer is that it isn’t.
To lower your risk from excess fluoride Plum Spring Clinic recommends the following steps:
- Choose organic foods when possible. Especially foods listed on the EWG Dirty Dozen which contain the highest amounts of pesticide.
- Limit intake of processed and prepacked foods and beverages.
- Be sure not to swallow any dental hygiene products, especially those containing fluoride. Rinse your mouth out well after use.
- Limit intake of tea, especially black tea, to a maximum of 4 cups per day. Avoid frequent intake of commercially brewed tea products.
- Avoid frequent intake of mechanically processed/separated/deboned meats (e.g., chicken fingers, nuggets, sticks, etc).
- Avoid using Teflon coated cooking pans. If you must use a non-stick pan, use only soft cooking implements and avoid metal implements which can scratch the surface of the pan.
- If you live in an area with fluoridated water, use a water filter for all drinking and cooking water.
- Pregnant women, nursing mothers, and young children who have not learned how to not swallow dental hygiene products should avoid the use of fluoridated dental products.
To ensure the health of your teeth and gums Plum Spring Clinic recommends that everyone should regularly brush their teeth, avoid excessive intake of sugary foods and beverages, and visit your dentist regularly.