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More than200 million peoplein the United States be in area where fluoride is added to tap water . According to the most late data available,24 other countriesaround the humans — include the United Kingdom , Brazil and Canada — append fluoride to their drinking water supply , and many other jurisdictions terminate up ingesting fluoride via naturally come about deposits in their water source .
Water fluoridation has been extol as one of thetop public wellness achievements of the twentieth centuryby the U.S. Centers for Disease Control and Prevention ( CDC ) . But the exercise has long been controversial , with vocal opponents indicate that the water system fluoridation has adverse health or cognitive impacts .
Fluoride is added to tap water in many countries around the world. But why?
So why do we tot up fluoride to pee in the first space ? And what do we know about its safety ?
How water fluoridation began
The history of water fluoridization begins in the other 20th century , when a young dentist namedDr . Frederick McKaynoticed a strange phenomenon in Colorado Springs . Residents of the Ithiel Town had typical brown , mottle stains on their tooth . Further reflection revealed that , despite these celebrated stain , people with the " Colorado brownish grease " seemed to have teeth that were remarkably resistant to decay . Tooth decay , also called caries or cavities , causes yap to make in teeth .
Researchers traced the grounds of the stain to the town ’s weewee supply , which contained abnormally high levels of fluoride . This finding prompted dentists to inquire whether it was potential to glean the good , tooth - protect effects of fluoridated water without experience the downside of staining your teeth .
In 1945 , Grand Rapids , Michigan , became the first city in the reality to okay apilot water fluoridation program . research worker added a small amount of fluoride to the city ’s H2O supplying and measured rates of tooth decay in the town ’s almost 30,000 schoolchildren over the next decennary . Their findings revealed that children who were born after water fluoridation lead off had more than 60 % few cavities than those born prior to the program .
Related : How does fluoride prevent cavities ?
The benefits of fluoridated water
Since 1945 , water fluoridation has proliferated as a far-flung public wellness praxis around the world , and formation such as the American Dental Association ( ADA)stand firmly in support of water fluoridation . Many studies support the opinion thatwater fluoridation prevents tooth decay in children .
" Fluoride was found to significantly reduce tooth decay,“Neil Maniar , a prof of public wellness practice at Northeastern University , told Live Science in an electronic mail . " set [ it ] in the water supply is a form of passive prevention that can improve oral health . "
Althoughfluoridated toothpastehas many of the same tooth - protecting properties of fluoridated piddle , experts say the latter comes with sure public wellness benefits that toothpaste deficiency . That ’s because ingesting fluoride , rather than brushing with it , leads to moreconstant levels of fluoride in the sass throughout the day , which is especially good for kid with developing tooth . Fluoridated piss also provides a baseline level of protective cover for low - income the great unwashed who may not have consistent admittance to fluoridated toothpaste or to other pattern of dental care .
" It is a way for everyone in a community to profit from fluoride in a price - effective manner , " Maniar sound out . " While we often take admittance to a dentist and even something as simple as being able to sweep tooth double a day for cede , this is a challenge in many communities . "
That was true in decades past — but some recent research is raising the question of how helpful fluoridated water is for cavity bar .
A review of over 150 written report showed that , in recent years , water fluoridationmay not be as effectual at preventing cavities as it was in the seventies , after fluoridated toothpaste became more widespread . This change may be because fluoridate toothpaste is provide enough benefit that fluoridated water no longer makes as striking of a difference .
However , it ’s important to note that the review did not let in any studies from low - income countries , where fluoridated toothpaste may be less pronto usable . The review also notes that challenges in measure the effects of fluoridization program make their potential benefits difficult to measure over time .
Is fluoridated water safe?
Both theCDCand theADAmaintain that at the stage found in the public water supplying — about0.7 mg per liter — fluoride is good to public dental health and carry few documented peril .
Still , fluoride has been the focus of much base hit research , and the topic continue to be a affair of public interest and tilt .
It ’s well known that unreasonable fluoride consumption can conduce tofluorosis , the condition behind the " Colorado brownish smear " observed by McKay in Colorado Springs . Dental fluorosis causes mottled ashen , yellow-bellied or brownish spots and stains to come out on the teeth . But it does not compromise oral health .
Consuming even higher levels of fluoride over a long point of meter can also take to a condition calledskeletal fluorosis , which compromises the integrity of the bones . This is because excessive deposits of fluoride in the skeleton causes the clappers to become hard and brickly , making them more susceptible to fractures .
Both dental fluorosis and skeletal fluorosis by and large occur in regions with abnormally gamey levels of natural fluoride deposit that leach into the water system supply . Because skeletal fluorosis need extremely high levels of fluoride photograph , it ’s mostly observed in regions withfluoride - contaminated groundwater , but dental fluorosis can take place due tolow - level fluoride exposure through artificially fluoridated weewee .
Initial business about fluoridated pee focus on whether itcould cause cancer . This opinion stanch from the possibility that fluoride build - up in the maturation denture of the bones could lead to osteosarcoma , a type of os Cancer the Crab . While this connexion is unmanageable to judge in humans , most studies have not happen any firm grounds for such a data link .
Does fluoride affect IQ?
More latterly , business organisation have been raised about the likely neurotoxic effects of fluoride .
A litigious 2024 monograph from the U.S. National Toxicology Program ( NTP ) appear back at dozens of studies and reported thathigh levels of fluoride exposure were connect with miserable intelligence quotient in fry . Between fry with high and miserable photo grade , the mediocre I.Q. difference of opinion amount to about one or two point .
However , the levels of fluoride pic associated with intelligence quotient changes were about double the levels of fluoride feel in water supply of countries like the U.S. or the U.K. — about 1.5 mg per liter . The authors also note that , while high fluoride degree are correlated with cognitive difference in children , their results do not show that fluoride is acauseof cognitive change .
Recently , further doubtfulness has been cast on the studies that find a link between fluoride and minify IQ . Reviewers at the National Academies of Science , Engineering , and Medicine pointed out major methodological and statistical problems with the NTP ’s monographtwicebefore the NTP self - published the account .
A newfangled clause that recapitulate the consequence of the NTP monograph was later published in January 2025 , and researchers then point out that about70 % of the study included in the meta - analysis were at mellow hazard of prejudice . The tie-up the NTP found between gamey levels of fluoride and IQ may not be honest , these scientist concluded , summate that the report allow " no evidence of an adverse effect at the lower piddle fluoride floor " used by fluoridation programs .
Still , some researchers are continue to investigate the minimum amount of fluoride that could potentially have neurologic effects . So far , theresults are motley — a few dozen studies have reported a relationship between aspects of cognition , such as executive purpose or IQ , and the levels of fluoride exposure establish in by artificial means fluoridated water supplying . But many others have failed to replicate this radio link .
Many studies that wed fluoride to negative effects have been pitiful calibre , meaning they may suffer from issues such as small sample sizes or using inconsistent or inaccurate method acting . High - quality studies have been less probable to show a connexion between fluoride exposure and negative cognitive termination .
make a determination about the rubber of fluoride is challenging because when private field employ varied methods , concentrate on dissimilar populations , or examine separate issue , it becomes hard to compare across those studies . And because different studies find conflicting results , it ’s not potential to point to a single study that can prove or disprove the safe of fluoride . As a result , many experts say more in high spirits - timber inquiry is still ask to guide a decision on the guard of fluoride .
" It ’s a very nuanced issue,“Deborah Dewey , a prof of pediatrics and community health sciences at the University of Calgary and the author of astudy investigating fluoride exposure and executive function in preschoolers , told Live Science . " I do n’t retrieve there ’s a right or incorrect answer right now . "
Fluoride and oral health equity
Ultimately , Maniar said the conversation about fluoride really needs to be a discussion about amend oral health equity .
— Are teeth considered bone ?
— Should you floss before or after you brush your teeth ?
— Which teeth fall out ?
" Rather than focusing on fluoridation , we should be talking about the disparities that exist in oral health care , the price incumbrance of routine unwritten wellness care , and the pregnant gaps that exist related to Education Department on oral health , " Maniar said .
" The linkage between unwritten health and a range of serious health issues is becoming more exculpated every day , " he said , refer to research that connects pitiable oral wellness and experimental condition includingheart disease and pneumonia . " It ’s critical that we deploy all available tools to address unwritten wellness in the same fashion that we would handle forcible and mental health . "
This clause is for informational purposes only and is not meant to offer aesculapian advice .
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