I like the inclusion of a diverse array of perspectives, and condescension or whatever tone is fine too. If the tone is too snarky, I don't have to finish reading! In short I support whatever the opposite of an echo chamber is.
The author appears to have gone lemming about Europe.
The author may be thinking of Europe of the 19th century. But now the population's embrace of science has waned. It loves homeopathy and has anti-vaxers galore. (The US had under 300 cases of measles last year; Europe had over 35,000.)
Europe is a patchwork of approaches to fluoride. Much of Europe depends on well water or have communities too small to make fluoridation financially viable. Some countries have enough or too much fluoride in ground water. A number of countries in Europe and Latin American put fluoride in table salt or milk to get that all important systemic effect. (See link to maps below)
Six million (out of 68 million) in the UK now have fluoridated water, which explains why British teeth have never been something to write home about. I recommend the British Fluoridation Society for info: https://bfsweb.org
I'm comfortable with opposing views, and I am a fan of Sensible Medicine. My negative reaction to that article was primarily because of its ridiculously snarky, arrogant, and condescending presentation, not its content. It reminds me why time and time again science has been held back by establishment critics who are so utterly convinced that they were right that they spent more time on ad hominen attacks than engaging in scientific discourse.
Spot on John. As far as fluoride is concerned there is no need to have it in drinking water. After all most toothpastes have fluoride, and a dentist will put a concentrate fluoride gel (not ingested) on a child’s teeth. So why bother contaminating the drinking water with fluoride whose long term consequences may not be so great.
Toothpaste only remineralizes teeth for about 2 hours. Ingesting fluoridated water and food made with that water provides remineralizing round the clock.
"Contaminating" drinking water? What nonsense. Fluoride is a nutrient mineral, like calcium and iron. It is a very common mineral; it is everywhere and in all ground water. But some ground water doesn't have enough to be helpful in making teeth and bones stronger. Fluoridation simply adds more fluoride ions.
Fluoridation has been studied continually for 80 years – that's several generations. There is nothing that has been studied as much as fluoride. At least 5 systematic reviews found it safe and beneficial.
Dr. M., keep up the good work. Controversy and disagreement is a great way to learn. May I add that, although I appreciate the many research studies that you review, I would like to see more case reviews with differing opinions and the resulting outcomes.
Bottom line: historically there were 3 College Administrators per 100 students, and student debt was for the most part, non existent.
Today, colleges have almost 14 Administrators per 100 student and everyone knows the college/student debt situation.
That in turn forces everyone to choose a career in mediocrity working for a State/Federal/etc. organization that will relieve the debt after 10 years of credited service.
Thus, Canada as an example, now has 40 government employees for every 100 workers.
What could 40 workers per 100 produce that clearly benefits themselves and the remaining 60 taxpaying citizens supporting their lavish (mediocre) lifestyle of included healthcare, pension, salary, vacations/holidays, retirement benefits, etc.??
Back to water and clean water and Trump reducing the annual budget by $2.48 billion.
The 'Ratchet Effect" supports that this is impossible, because it actually might cause the reduction of workers, not the quality of water.
But those workers will clearly destroy the quality of water in an effort to cling to their job.
Charles coined it as 'cutting muscle to maintain fat'.
We're going to see a lot more of this going forward.
If we hit 40 gov't employees per 100 workers USA, who prey=tell, might those 40 workers vote for next election cycle?
Thank you, JMM, for reminding everyone that disagreement is often healthy, and that throwing money at a problem does not correlate with solutions. I give you the state of California as Exhibit A... :)
We have fluoride toothpaste. An Engineer friend who has worked in a water treatment plant did not want fluoride in his drinking water mainly because of people possibly making errors and putting in too much fluoride.
Toothpaste is topical and remineralizes teeth for about 2 hours. Fluoridated water is systemic and provides continual remineralization for teeth and bones.
American "experts" have pushed this chemical lobotomy onto our country. We fight against our govt to remove it but they are blackmailed by america to keep poisoning us and retarding our children KNOWINGLY. This is just one more example of AMERICAN CORPORATE TERRORISM. Makes me VOMIT when i hear yanks chanting "WE ARE THE GREATEST COUNTRY IN THE WORLD"..... Greatest WHAT country? Greatest terrorist country? Greatest satanic country? Greatest WEAPONISED PSYOP country? YOUR killshots are destroying OUR people GROOMERICA.... YOUR KILLSHOTS. Just like Germans killed all those jews, we are told. THIS IS THE AMERICAN CORPORATE HOLICAUST...
Lower cognitive scores, >2-point IQ reduction per 0.5 mg/L increase
Los Angeles Cohort Study
Los Angeles, USA
229
Maternal urinary fluoride, +0.68 mg/L
Not assessed
Nearly double odds of neurobehavioral problems at 36 months
Systematic Review/Meta-Analysis
Key Finding
Confidence Level
Relevant Fluoride Level
2023 Dose-Response Meta-Analysis
Higher fluoride linked to -4.68 IQ point difference
Moderate
>1 mg/L in drinking water
NTP Monograph (2024)
Higher fluoride (>1.5 mg/L) associated with lower IQ
Moderate
>1.5 mg/L
2025 JAMA Pediatrics Meta-Analysis
Higher exposure linked to 1.63 IQ point decrease per urine increase
Statistically significant
Not specified, urine-based
Limitations and Considerations
• Study Design: Most longitudinal studies are observational, adjusting for covariates like socioeconomic status, but residual confounding (e.g., from other environmental toxins) cannot be fully ruled out.
• Fluoride Levels: Adverse neurological effects are more consistently observed at higher fluoride concentrations (≥1.5 mg/L), above the U.S. recommended level of 0.7 mg/L. Evidence at lower levels is less conclusive, with the NTP noting insufficient data at 0.7 mg/L.
• Autism-Specific Evidence: No longitudinal study directly establishes a causal link between fluoride and ASD, though the Florida study suggests an association, relying on diagnostic codes rather than clinical assessments.
• Need for Further Research: The NTP and other reviews, such as a 2021 systematic review (A systematic review and meta-analysis of the association between fluoride exposure and neurological disorders), emphasize the need for more high-quality longitudinal studies to clarify causality, especially at lower exposure levels typical of U.S. water fluoridation.
Risk-Benefit Tradeoff
The Florida study highlights a tradeoff: a modest reduction in tooth decay (58/1,000 children) versus potential increases in neurodevelopmental disorders (e.g., 11/1,000 for ASD). This suggests that while fluoride’s dental benefits are clear, its safety at current levels warrants scrutiny, particularly for vulnerable populations like pregnant women and young children. Major health organizations (CDC, American Dental Association, American Academy of Pediatrics) maintain that fluoride at 0.7 mg/L is safe and effective, but recent legal challenges and state bans (e.g., Florida, Utah) reflect ongoing controversy.
Conclusion
Longitudinal evidence confirms fluoride’s beneficial effect on dentition, reducing tooth decay by up to 35% at optimal levels. However, there is emerging evidence of potential neurodevelopmental risks, including slight increases in ASD, ADHD, ID, and developmental delays, particularly at higher fluoride levels (≥1.5 mg/L). The Florida Medicaid Cohort Study is the most comprehensive longitudinal study addressing both outcomes, but its findings on neurodevelopmental risks are not conclusive due to methodological limitations. More robust longitudinal studies are needed to clarify these risks, especially at lower exposure levels, to inform public health policy and address community concerns.
Key Citations
• Tooth decay prevention and neurodevelopmental disorder risk following childhood fluoride exposure
• Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6-12 years in Mexico
• Maternal Urinary Fluoride and Child Neurobehavior at Age 36 Months
• Fluoride exposure and cognitive neurodevelopment: Systematic review and dose-response meta-analysis
• Fluoride Exposure: Neurodevelopment and Cognition
• Fluoride Exposure and Children’s IQ Scores: A Systematic Review and Meta-Analysis
• Achievements in Public Health, 1900-1999: Fluoridation of Drinking Water to Prevent Dental Caries
• Does adding fluoride to water supplies prevent tooth decay?
• A systematic review and meta-analysis of the association between fluoride exposure and neurological disorders
• Research suggests fluoride in drinking water reduces tooth decay, especially in children, with benefits seen in long-term studies.
• The evidence leans toward potential negative effects on neurologic development, like lower IQ and increased risks of autism and developmental delays, particularly at higher exposure levels.
• Findings are mixed, with some studies showing risks at levels above the U.S. recommended 0.7 mg/L, while others find no clear harm at lower levels, highlighting ongoing debate.
Beneficial Effects on Dentition
Fluoride in drinking water has been shown to significantly reduce tooth decay, a key benefit supported by decades of research. For example, the Florida Medicaid Cohort Study found that children exposed to fluoridated water had a lower risk of tooth decay, with the incidence rate being 3.6 times lower compared to unexposed children (Tooth decay prevention and neurodevelopmental disorder risk following childhood fluoride exposure). Historical data also supports this, with reductions up to 35% in children from fluoridated communities.
Potential Negative Effects on Neurologic Development
There is growing evidence that higher fluoride levels may negatively affect neurologic maturity, especially in children. The Florida Medicaid Cohort Study noted slight increases in risks for autism spectrum disorder (ASD), intellectual disability (ID), ADHD, and specific developmental delays (SDD) in fluoride-exposed children. Other studies, like the ELEMENT Cohort Study in Mexico, found that higher maternal urinary fluoride was linked to lower cognitive scores in children (Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6-12 years in Mexico). A 2025 meta-analysis also suggested a connection between higher fluoride exposure and lower IQ scores (Fluoride Exposure and Children’s IQ Scores: A Systematic Review and Meta-Analysis).
Considerations and Controversy
The evidence is complex, with risks more pronounced at fluoride levels above 1.5 mg/L, while the U.S. recommends 0.7 mg/L, where effects are less clear. This has sparked debate, with some health organizations supporting fluoridation for dental benefits, while others call for more research on neurologic risks, especially for vulnerable groups like pregnant women and young children.
Survey Note: Comprehensive Analysis of Fluoride Effects in Drinking Water
This survey note provides a detailed examination of longitudinal evidence regarding the dual effects of fluoride in drinking water, focusing on its benefits for dentition and potential negative impacts on neurologic maturity, particularly in children, including relationships to developmental delay, autism, and other adverse diagnoses. The analysis is grounded in recent studies and reviews, ensuring a comprehensive overview as of June 8, 2025.
Background and Context
Fluoride in drinking water has been a cornerstone of public health since the mid-20th century, primarily for its role in preventing dental caries. However, recent research has raised concerns about potential neurotoxic effects, particularly during early development, leading to a polarized debate. This note synthesizes longitudinal evidence to address both aspects, acknowledging the complexity and ongoing research needs.
Longitudinal Evidence on Beneficial Effects for Dentition
Fluoride’s role in reducing tooth decay is well-documented through longitudinal studies, which track the same populations over time to assess dental health outcomes. Key findings include:
• Florida Medicaid Cohort Study (1990–2012):
◦ This study, involving 73,254 children continuously enrolled in Florida Medicaid for their first 10 years, found that fluoride exposure in the year of birth slightly reduced the risk of tooth decay (TD), with a dose-dependent effect (odds ratio [OR] = 0.996, adjusted OR [aOR] = 0.994). Over the first 10 years, fluoride-exposed children had a significantly lower TD risk compared to unexposed (OR = 0.263, aOR = 0.345), with the incidence rate being approximately 3.6-fold lower and an attributable risk of about 6 per 100 children (Tooth decay prevention and neurodevelopmental disorder risk following childhood fluoride exposure).
◦ These findings align with historical longitudinal data, where community water fluoridation at 0.7 mg/L has been credited with reducing tooth decay by up to 35% in children, as noted by the Centers for Disease Control and Prevention (CDC) (Achievements in Public Health, 1900-1999: Fluoridation of Drinking Water to Prevent Dental Caries).
• Other Historical Data:
◦ Longitudinal studies, such as those reviewed by the CDC, have consistently shown that fluoridated water reduces caries prevalence, particularly in children, with effects seen across decades of implementation. A 2024 Cochrane Review found slight increases in caries-free children post-1975, though effect sizes have diminished with widespread fluoride toothpaste use (Does adding fluoride to water supplies prevent tooth decay?).
Longitudinal Evidence on Potential Negative Effects on Neurologic Development
Emerging longitudinal evidence suggests that fluoride exposure, particularly at higher levels, may negatively impact neurologic maturity, with implications for developmental delay, ASD, ADHD, and ID. Key studies include:
• Florida Medicaid Cohort Study (1990–2012):
◦ The same cohort of 73,254 children showed that fluoride exposure in the year of birth slightly increased risks for neurodevelopmental disorders (NDs): ASD (aOR = 1.005), ID (aOR = 1.006), ADHD (aOR = 1.001), and specific developmental delays (SDD) (aOR = 1.002). Over the first 10 years, risks were notably higher for ASD (aOR = 5.575), ID (aOR = 3.868), and SDD (aOR = 1.505) in fluoride-exposed versus unexposed children.
◦ Incidence rates were higher in exposed children: for ASD, the risk ratio was 6.26 with an attributable risk of 1.05 per 100; for ID, the risk ratio was 2.02 with an attributable risk of 0.49 per 100; for SDD, the risk ratio was 1.24 with an attributable risk of 4.90 per 100 (Tooth decay prevention and neurodevelopmental disorder risk following childhood fluoride exposure).
◦ The study suggests mechanisms like increased oxidative stress, synaptic dysfunction, and mitochondrial/energy metabolism disruption may contribute to these effects.
• ELEMENT Cohort Study (Mexico):
◦ This longitudinal study followed pregnant women and their children, measuring maternal and child urinary fluoride levels. Higher maternal urinary fluoride (mean: 0.90 mg/L) was associated with lower cognitive scores in children at ages 4 (General Cognitive Index, McCarthy Scale) and 6–12 years (Wechsler Abbreviated Scale of Intelligence, WASI). Each 0.5 mg/L increase in creatine-adjusted maternal urinary fluoride was associated with a >2-point reduction in global cognitive functioning/IQ (Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6-12 years in Mexico).
◦ The study supports a link between prenatal fluoride exposure and adverse cognitive outcomes, though it did not specifically assess ASD or ADHD.
• Los Angeles Cohort Study (2024):
◦ This study of 229 mother-child pairs found that higher maternal urinary fluoride levels (increase of 0.68 mg/L) nearly doubled the odds of neurobehavioral problems in children at 36 months, including symptoms related to ADHD and developmental delays, using the Child Behavior Checklist (CBCL) (Maternal Urinary Fluoride and Child Neurobehavior at Age 36 Months).
• Systematic Reviews and Meta-Analyses:
◦ A 2023 systematic review and dose-response meta-analysis found that higher fluoride exposure, particularly from drinking water, is associated with lower IQ scores in children, with a summary mean difference of -4.68 IQ points comparing highest versus lowest fluoride categories (Fluoride exposure and cognitive neurodevelopment: Systematic review and dose-response meta-analysis). Dose-response analysis showed a linear IQ decrease for water fluoride above 1 mg/L, with -3.05 IQ points per 1 mg/L up to 2 mg/L, becoming steeper above this level.
◦ The National Toxicology Program (NTP) monograph (2024) concluded with moderate confidence that higher fluoride levels (>1.5 mg/L) are associated with lower IQ in children, based on epidemiology studies in Canada, China, India, Iran, Pakistan, and Mexico, though insufficient data exist to determine effects at 0.7 mg/L (Fluoride Exposure: Neurodevelopment and Cognition).
◦ A 2025 meta-analysis in JAMA Pediatrics found a statistically significant association between higher fluoride exposure and lower children’s IQ scores, with each small increase in fluoride found in kids’ urine associated with a decrease of 1.63 IQ points (Fluoride Exposure and Children’s IQ Scores: A Systematic Review and Meta-Analysis).
Did a quick ChatGPT AI search and came up with this to ponder.
Here’s a structured summary of longitudinal evidence on fluoride in drinking water, addressing its benefits to teeth and potential neurologic/health concerns, especially in children:
• Grand Rapids Trial & early US/Canada trials (~1945–1960s): Communities with fluoridated water showed 48–70% reduction in cavities among 12–14‑year-olds after 13–15 years of fluoridation  .
• Australian adult cohorts (pre‑1960 vs 1960–1990 lifelong exposure):
Adults with >75% lifetime fluoridated water exposure had 10–11% fewer decayed, missing, and filled teeth (DMF‑Teeth) and 21–30% fewer DF‑Surfaces than those with <25% exposure .
• Danish 10‑year registry study (5‑ and 15‑year-olds): Demonstrated a significant negative association between fluoride concentration and dental caries across large cohorts .
• Cochrane 2015 review: Concluded community water fluoridation yields a 35% reduction in baby‑tooth decay and 26% reduction in permanent‑tooth decay when other fluoride sources are not available .
• CDC 2024 statement: Reviews 2.25 fewer decayed teeth per child and ~25% fewer cavities in adults and children due to fluoridation .
⸻
⚠️ 2. Adverse Dental Effects – Fluorosis
• NHANES data (US children 6–15 years): Fluorosis prevalence rose from 23% in 2004 to 68–87% by 2013–2016; primarily mild fluorosis, with minimal impact on appearance or quality of life .
• Systematic reviews confirm a correlation between high fluoride intake (≥6 mg /L) and dental fluorosis/fluoride-related bone effects .
⸻
🧠 3. Neurologic & Neurodevelopmental Effects
3.1 Cognition (IQ and Neurotoxicity)
• Meta‑analysis of 33 studies: Across various exposure types, high fluoride exposure correlated with −4.68 IQ points (−5.60 for water-specific exposure). IQ decreased by ~3 IQ points per 1 mg /L increase, particularly above 1 mg /L. Note: studies with low risk of bias did not show adverse effects .
• DARE 2020 meta-analysis: Found a standardized mean difference in intelligence of −0.29 to −0.45 SD in children; higher fluoride exposure doubled the risk of scoring low on CRT-RC (cognitive test) .
• 2024–2025 U.S. govt & JAMA Pediatrics summary:
• HHS 2024 report: Water >1.5 mg/L linked to lower IQ; below that, data are inconclusive.
• JAMA Pediatric meta‐analysis: Each 1 mg/L urinary fluoride rise correlates with a ~1.14–1.63 IQ point drop .
3.2 ADHD / Behavioral Disorders
• NTP systematic review (2022):
• Four studies (US, Canada, China, Mexico): Significant positive association between fluoride and ADHD/learning disabilities. Examples include:
• In Canada, a >6‑fold higher odds of ADHD per 1 mg/L increase in tap‑water fluoride, and +0.31 points in hyperactivity/inattention scales .
3.3 IQ in Developed Countries
• Australian longitudinal study of early exposure: No difference in IQ, emotional/behavioral development, or executive function between children exposed or unexposed to fluoridated water . This aligns with other major reviews (NHMRC 2017, Guth 2020).
⸻
📊 4. Contextual Summary
Domain Benefit / Risk Magnitude / Quality
Dental caries prevention ≈25–60% reduction Strong evidence from longitudinal trials and reviews
Dental fluorosis Mild cases common (20–40%) Severe cases very rare
Lower IQ −1 to −5 IQ points per 1 mg/L Mostly in studies ≥1 mg/L, with bias concerns
Behavioral/Executive Effects None observed in robust Australian cohort Reinforced by systematic reviews
⸻
🧾 5. Conclusions & Considerations
1. Dental benefits of fluoride are well-supported over decades of longitudinal, population-wide data.
2. Mild dental fluorosis is the most common non-toxic adverse effect; cosmetic concern only.
3. Neurologic concerns—dropped IQ and ADHD risk—appear in many studies at higher fluoride exposures (≥1 mg/L), especially in developing countries. However, some high-quality, low‑bias studies found no negative impact at CDC‑recommended levels (0.7 mg/L).
4. No credible evidence links fluoridation to autism, developmental delay per se, or cancer/osteosarcoma.
⸻
📌 6. Research Gaps & Recommendations
• More prospective, low-bias studies at common U.S. exposure levels (0.7 mg/L) are needed.
• Behavioral/ADHD outcomes require further longitudinal clarity.
• Review the total fluoride intake (water + toothpaste + diet) in children, especially under age 4.
⸻
✅ Sources
• Early trials & CDC data on decay reduction      
• Adult dental benefit studies
• Dental fluorosis statistics & trends 
• Cognitive neurotoxicity meta-analyses 
• ADHD/behavioral disorder links 
• Australian longitudinal null findings 
⸻
Bottom line: Community water fluoridation at recommended concentrations (0.7 mg/L) is a proven method to significantly reduce tooth decay. Mild dental fluorosis is generally cosmetic. There is suggestive evidence of neurodevelopmental effects at higher exposures, but findings are inconsistent and often confounded. Continued high‑quality studies—especially in non‑fluoridated vs fluoridated populations—are essential to resolve these concerns.
Mild dental fluorosis means that the teeth are especially resistant to decay. The "cosmetic" effect of mild fluorosis is a whitening of the teeth, though it can be spotty.
Don’t appease the whiners (or the loudest and squeakiest wheels). I am curious as to how many readers complained, as a fraction of your entire readership. My suspicion is it was a small minority.
Resist the temptation to be captured by your audience.
This stack is great for hosting disparate views. If people can’t handle some differences in opinion, they shouldn’t let the door hit them in their backsides.
Besides, fluoride was just one point among several made yesterday. Unless there were some pro-cholera dissenters that I missed.
This site promotes critical and independent thought. So it naturally attracts those with a contrarian lean. But the irony is that some among this cohort can’t seem to handle reading things they disagree with. (Or at least can’t disagree by making an argument about the point of disagreement, but instead wonder why they had to be exposed to something they disagree with in the first place). It’s a weird dynamic I also see at The Free Press.
Show me one scientific argument in the first post... the author didn't make a single one. She started out with the premise that the budget cuts were bad and fluoride is good. Provided no "sensible" arguments for why... no detail on the cuts or how they would link to cholera or other GI illnesses. No real reason why water is suddenly expected to become non potable.
Maybe the reason isn't that people disagree with the post but with the lack of scientific argument. VP has certainly posted items that created a lot of "uproar" but go back and read what he wrote-- it was well reasoned and had clear arguments.
I like the inclusion of a diverse array of perspectives, and condescension or whatever tone is fine too. If the tone is too snarky, I don't have to finish reading! In short I support whatever the opposite of an echo chamber is.
The author appears to have gone lemming about Europe.
The author may be thinking of Europe of the 19th century. But now the population's embrace of science has waned. It loves homeopathy and has anti-vaxers galore. (The US had under 300 cases of measles last year; Europe had over 35,000.)
Europe is a patchwork of approaches to fluoride. Much of Europe depends on well water or have communities too small to make fluoridation financially viable. Some countries have enough or too much fluoride in ground water. A number of countries in Europe and Latin American put fluoride in table salt or milk to get that all important systemic effect. (See link to maps below)
Six million (out of 68 million) in the UK now have fluoridated water, which explains why British teeth have never been something to write home about. I recommend the British Fluoridation Society for info: https://bfsweb.org
I also recommend the author check out the ADA on fluoride and also what happened to Calgary when it stopped fluoridation for ten years. (https://adanews.ada.org/ada-news/2021/august/community-water-fluoridation-prevents-caries/)
Maps here:
https://s3-us-west-2.amazonaws.com/cdhp-fluoridation/Marthaler+(2011)+Salt+Fluoridation.pdf#:~:text=Europe%20and%20Latin%20America%20are%20currently%20the,with%20implemented%20successful%20programs%20of%20salt%20fluoridation.&text=Nowadays%20in%20eight%20European%20countries%20national%20legal,Republic%2C%20France%2C%20Germany%2C%20Greece%2C%20Netherlands%2C%20Spain%2C%20Switzerland.
I'm comfortable with opposing views, and I am a fan of Sensible Medicine. My negative reaction to that article was primarily because of its ridiculously snarky, arrogant, and condescending presentation, not its content. It reminds me why time and time again science has been held back by establishment critics who are so utterly convinced that they were right that they spent more time on ad hominen attacks than engaging in scientific discourse.
100%
This reminded me of the movie "Love in the Afternoon." Sorry to digress but... her comment about Americans was and still is hysterical.
Spot on John. As far as fluoride is concerned there is no need to have it in drinking water. After all most toothpastes have fluoride, and a dentist will put a concentrate fluoride gel (not ingested) on a child’s teeth. So why bother contaminating the drinking water with fluoride whose long term consequences may not be so great.
Toothpaste only remineralizes teeth for about 2 hours. Ingesting fluoridated water and food made with that water provides remineralizing round the clock.
"Contaminating" drinking water? What nonsense. Fluoride is a nutrient mineral, like calcium and iron. It is a very common mineral; it is everywhere and in all ground water. But some ground water doesn't have enough to be helpful in making teeth and bones stronger. Fluoridation simply adds more fluoride ions.
Fluoridation has been studied continually for 80 years – that's several generations. There is nothing that has been studied as much as fluoride. At least 5 systematic reviews found it safe and beneficial.
But don't trust me. Talk to your dentist.
Is that why so many European countries no longer fluoridate their water?
Dr. M., keep up the good work. Controversy and disagreement is a great way to learn. May I add that, although I appreciate the many research studies that you review, I would like to see more case reviews with differing opinions and the resulting outcomes.
Switzerland fluoridates it's salt not its water. Read the BBC article : These countries dont fluoridate their water heres why.
Dr. Mandrola,
Thanks for your writings and attempt to clarify the obvious.
One side note, but relevant point to add, is the need for governments to continually grow and take more control of their dominions.
Charles Hugh Smith wrote an interesting article titled "The Ratchet Effect".
https://charleshughsmith.substack.com/p/the-ratchet-effect-easy-to-spend
Bottom line: historically there were 3 College Administrators per 100 students, and student debt was for the most part, non existent.
Today, colleges have almost 14 Administrators per 100 student and everyone knows the college/student debt situation.
That in turn forces everyone to choose a career in mediocrity working for a State/Federal/etc. organization that will relieve the debt after 10 years of credited service.
Thus, Canada as an example, now has 40 government employees for every 100 workers.
What could 40 workers per 100 produce that clearly benefits themselves and the remaining 60 taxpaying citizens supporting their lavish (mediocre) lifestyle of included healthcare, pension, salary, vacations/holidays, retirement benefits, etc.??
Back to water and clean water and Trump reducing the annual budget by $2.48 billion.
The 'Ratchet Effect" supports that this is impossible, because it actually might cause the reduction of workers, not the quality of water.
But those workers will clearly destroy the quality of water in an effort to cling to their job.
Charles coined it as 'cutting muscle to maintain fat'.
We're going to see a lot more of this going forward.
If we hit 40 gov't employees per 100 workers USA, who prey=tell, might those 40 workers vote for next election cycle?
Keynesian Economics or Austrian?
The answer will be in your ballot box soon.
Thank you, JMM, for reminding everyone that disagreement is often healthy, and that throwing money at a problem does not correlate with solutions. I give you the state of California as Exhibit A... :)
Yes!
We have fluoride toothpaste. An Engineer friend who has worked in a water treatment plant did not want fluoride in his drinking water mainly because of people possibly making errors and putting in too much fluoride.
Toothpaste is topical and remineralizes teeth for about 2 hours. Fluoridated water is systemic and provides continual remineralization for teeth and bones.
American "experts" have pushed this chemical lobotomy onto our country. We fight against our govt to remove it but they are blackmailed by america to keep poisoning us and retarding our children KNOWINGLY. This is just one more example of AMERICAN CORPORATE TERRORISM. Makes me VOMIT when i hear yanks chanting "WE ARE THE GREATEST COUNTRY IN THE WORLD"..... Greatest WHAT country? Greatest terrorist country? Greatest satanic country? Greatest WEAPONISED PSYOP country? YOUR killshots are destroying OUR people GROOMERICA.... YOUR KILLSHOTS. Just like Germans killed all those jews, we are told. THIS IS THE AMERICAN CORPORATE HOLICAUST...
…Detailed Analysis and Tables
To organize the findings, the following tables summarize key longitudinal studies and their outcomes:
Study
Location
Sample Size
Fluoride Exposure
Dentition Outcome
Neurologic Outcome
Florida Medicaid Cohort Study
Florida, USA
73,254
0–100% by county
Reduced TD risk (OR = 0.263, aOR = 0.345)
Increased risks for ASD, ID, ADHD, SDD (e.g., ASD aOR = 5.575)
ELEMENT Cohort Study
Mexico
Not specified
Maternal urinary fluoride, mean 0.90 mg/L
Not assessed
Lower cognitive scores, >2-point IQ reduction per 0.5 mg/L increase
Los Angeles Cohort Study
Los Angeles, USA
229
Maternal urinary fluoride, +0.68 mg/L
Not assessed
Nearly double odds of neurobehavioral problems at 36 months
Systematic Review/Meta-Analysis
Key Finding
Confidence Level
Relevant Fluoride Level
2023 Dose-Response Meta-Analysis
Higher fluoride linked to -4.68 IQ point difference
Moderate
>1 mg/L in drinking water
NTP Monograph (2024)
Higher fluoride (>1.5 mg/L) associated with lower IQ
Moderate
>1.5 mg/L
2025 JAMA Pediatrics Meta-Analysis
Higher exposure linked to 1.63 IQ point decrease per urine increase
Statistically significant
Not specified, urine-based
Limitations and Considerations
• Study Design: Most longitudinal studies are observational, adjusting for covariates like socioeconomic status, but residual confounding (e.g., from other environmental toxins) cannot be fully ruled out.
• Fluoride Levels: Adverse neurological effects are more consistently observed at higher fluoride concentrations (≥1.5 mg/L), above the U.S. recommended level of 0.7 mg/L. Evidence at lower levels is less conclusive, with the NTP noting insufficient data at 0.7 mg/L.
• Autism-Specific Evidence: No longitudinal study directly establishes a causal link between fluoride and ASD, though the Florida study suggests an association, relying on diagnostic codes rather than clinical assessments.
• Need for Further Research: The NTP and other reviews, such as a 2021 systematic review (A systematic review and meta-analysis of the association between fluoride exposure and neurological disorders), emphasize the need for more high-quality longitudinal studies to clarify causality, especially at lower exposure levels typical of U.S. water fluoridation.
Risk-Benefit Tradeoff
The Florida study highlights a tradeoff: a modest reduction in tooth decay (58/1,000 children) versus potential increases in neurodevelopmental disorders (e.g., 11/1,000 for ASD). This suggests that while fluoride’s dental benefits are clear, its safety at current levels warrants scrutiny, particularly for vulnerable populations like pregnant women and young children. Major health organizations (CDC, American Dental Association, American Academy of Pediatrics) maintain that fluoride at 0.7 mg/L is safe and effective, but recent legal challenges and state bans (e.g., Florida, Utah) reflect ongoing controversy.
Conclusion
Longitudinal evidence confirms fluoride’s beneficial effect on dentition, reducing tooth decay by up to 35% at optimal levels. However, there is emerging evidence of potential neurodevelopmental risks, including slight increases in ASD, ADHD, ID, and developmental delays, particularly at higher fluoride levels (≥1.5 mg/L). The Florida Medicaid Cohort Study is the most comprehensive longitudinal study addressing both outcomes, but its findings on neurodevelopmental risks are not conclusive due to methodological limitations. More robust longitudinal studies are needed to clarify these risks, especially at lower exposure levels, to inform public health policy and address community concerns.
Key Citations
• Tooth decay prevention and neurodevelopmental disorder risk following childhood fluoride exposure
• Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6-12 years in Mexico
• Maternal Urinary Fluoride and Child Neurobehavior at Age 36 Months
• Fluoride exposure and cognitive neurodevelopment: Systematic review and dose-response meta-analysis
• Fluoride Exposure: Neurodevelopment and Cognition
• Fluoride Exposure and Children’s IQ Scores: A Systematic Review and Meta-Analysis
• Achievements in Public Health, 1900-1999: Fluoridation of Drinking Water to Prevent Dental Caries
• Does adding fluoride to water supplies prevent tooth decay?
• A systematic review and meta-analysis of the association between fluoride exposure and neurological disorders
For comparison, here’s what Grok came up with
Key Points
• Research suggests fluoride in drinking water reduces tooth decay, especially in children, with benefits seen in long-term studies.
• The evidence leans toward potential negative effects on neurologic development, like lower IQ and increased risks of autism and developmental delays, particularly at higher exposure levels.
• Findings are mixed, with some studies showing risks at levels above the U.S. recommended 0.7 mg/L, while others find no clear harm at lower levels, highlighting ongoing debate.
Beneficial Effects on Dentition
Fluoride in drinking water has been shown to significantly reduce tooth decay, a key benefit supported by decades of research. For example, the Florida Medicaid Cohort Study found that children exposed to fluoridated water had a lower risk of tooth decay, with the incidence rate being 3.6 times lower compared to unexposed children (Tooth decay prevention and neurodevelopmental disorder risk following childhood fluoride exposure). Historical data also supports this, with reductions up to 35% in children from fluoridated communities.
Potential Negative Effects on Neurologic Development
There is growing evidence that higher fluoride levels may negatively affect neurologic maturity, especially in children. The Florida Medicaid Cohort Study noted slight increases in risks for autism spectrum disorder (ASD), intellectual disability (ID), ADHD, and specific developmental delays (SDD) in fluoride-exposed children. Other studies, like the ELEMENT Cohort Study in Mexico, found that higher maternal urinary fluoride was linked to lower cognitive scores in children (Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6-12 years in Mexico). A 2025 meta-analysis also suggested a connection between higher fluoride exposure and lower IQ scores (Fluoride Exposure and Children’s IQ Scores: A Systematic Review and Meta-Analysis).
Considerations and Controversy
The evidence is complex, with risks more pronounced at fluoride levels above 1.5 mg/L, while the U.S. recommends 0.7 mg/L, where effects are less clear. This has sparked debate, with some health organizations supporting fluoridation for dental benefits, while others call for more research on neurologic risks, especially for vulnerable groups like pregnant women and young children.
Survey Note: Comprehensive Analysis of Fluoride Effects in Drinking Water
This survey note provides a detailed examination of longitudinal evidence regarding the dual effects of fluoride in drinking water, focusing on its benefits for dentition and potential negative impacts on neurologic maturity, particularly in children, including relationships to developmental delay, autism, and other adverse diagnoses. The analysis is grounded in recent studies and reviews, ensuring a comprehensive overview as of June 8, 2025.
Background and Context
Fluoride in drinking water has been a cornerstone of public health since the mid-20th century, primarily for its role in preventing dental caries. However, recent research has raised concerns about potential neurotoxic effects, particularly during early development, leading to a polarized debate. This note synthesizes longitudinal evidence to address both aspects, acknowledging the complexity and ongoing research needs.
Longitudinal Evidence on Beneficial Effects for Dentition
Fluoride’s role in reducing tooth decay is well-documented through longitudinal studies, which track the same populations over time to assess dental health outcomes. Key findings include:
• Florida Medicaid Cohort Study (1990–2012):
◦ This study, involving 73,254 children continuously enrolled in Florida Medicaid for their first 10 years, found that fluoride exposure in the year of birth slightly reduced the risk of tooth decay (TD), with a dose-dependent effect (odds ratio [OR] = 0.996, adjusted OR [aOR] = 0.994). Over the first 10 years, fluoride-exposed children had a significantly lower TD risk compared to unexposed (OR = 0.263, aOR = 0.345), with the incidence rate being approximately 3.6-fold lower and an attributable risk of about 6 per 100 children (Tooth decay prevention and neurodevelopmental disorder risk following childhood fluoride exposure).
◦ These findings align with historical longitudinal data, where community water fluoridation at 0.7 mg/L has been credited with reducing tooth decay by up to 35% in children, as noted by the Centers for Disease Control and Prevention (CDC) (Achievements in Public Health, 1900-1999: Fluoridation of Drinking Water to Prevent Dental Caries).
• Other Historical Data:
◦ Longitudinal studies, such as those reviewed by the CDC, have consistently shown that fluoridated water reduces caries prevalence, particularly in children, with effects seen across decades of implementation. A 2024 Cochrane Review found slight increases in caries-free children post-1975, though effect sizes have diminished with widespread fluoride toothpaste use (Does adding fluoride to water supplies prevent tooth decay?).
Longitudinal Evidence on Potential Negative Effects on Neurologic Development
Emerging longitudinal evidence suggests that fluoride exposure, particularly at higher levels, may negatively impact neurologic maturity, with implications for developmental delay, ASD, ADHD, and ID. Key studies include:
• Florida Medicaid Cohort Study (1990–2012):
◦ The same cohort of 73,254 children showed that fluoride exposure in the year of birth slightly increased risks for neurodevelopmental disorders (NDs): ASD (aOR = 1.005), ID (aOR = 1.006), ADHD (aOR = 1.001), and specific developmental delays (SDD) (aOR = 1.002). Over the first 10 years, risks were notably higher for ASD (aOR = 5.575), ID (aOR = 3.868), and SDD (aOR = 1.505) in fluoride-exposed versus unexposed children.
◦ Incidence rates were higher in exposed children: for ASD, the risk ratio was 6.26 with an attributable risk of 1.05 per 100; for ID, the risk ratio was 2.02 with an attributable risk of 0.49 per 100; for SDD, the risk ratio was 1.24 with an attributable risk of 4.90 per 100 (Tooth decay prevention and neurodevelopmental disorder risk following childhood fluoride exposure).
◦ The study suggests mechanisms like increased oxidative stress, synaptic dysfunction, and mitochondrial/energy metabolism disruption may contribute to these effects.
• ELEMENT Cohort Study (Mexico):
◦ This longitudinal study followed pregnant women and their children, measuring maternal and child urinary fluoride levels. Higher maternal urinary fluoride (mean: 0.90 mg/L) was associated with lower cognitive scores in children at ages 4 (General Cognitive Index, McCarthy Scale) and 6–12 years (Wechsler Abbreviated Scale of Intelligence, WASI). Each 0.5 mg/L increase in creatine-adjusted maternal urinary fluoride was associated with a >2-point reduction in global cognitive functioning/IQ (Prenatal fluoride exposure and cognitive outcomes in children at 4 and 6-12 years in Mexico).
◦ The study supports a link between prenatal fluoride exposure and adverse cognitive outcomes, though it did not specifically assess ASD or ADHD.
• Los Angeles Cohort Study (2024):
◦ This study of 229 mother-child pairs found that higher maternal urinary fluoride levels (increase of 0.68 mg/L) nearly doubled the odds of neurobehavioral problems in children at 36 months, including symptoms related to ADHD and developmental delays, using the Child Behavior Checklist (CBCL) (Maternal Urinary Fluoride and Child Neurobehavior at Age 36 Months).
• Systematic Reviews and Meta-Analyses:
◦ A 2023 systematic review and dose-response meta-analysis found that higher fluoride exposure, particularly from drinking water, is associated with lower IQ scores in children, with a summary mean difference of -4.68 IQ points comparing highest versus lowest fluoride categories (Fluoride exposure and cognitive neurodevelopment: Systematic review and dose-response meta-analysis). Dose-response analysis showed a linear IQ decrease for water fluoride above 1 mg/L, with -3.05 IQ points per 1 mg/L up to 2 mg/L, becoming steeper above this level.
◦ The National Toxicology Program (NTP) monograph (2024) concluded with moderate confidence that higher fluoride levels (>1.5 mg/L) are associated with lower IQ in children, based on epidemiology studies in Canada, China, India, Iran, Pakistan, and Mexico, though insufficient data exist to determine effects at 0.7 mg/L (Fluoride Exposure: Neurodevelopment and Cognition).
◦ A 2025 meta-analysis in JAMA Pediatrics found a statistically significant association between higher fluoride exposure and lower children’s IQ scores, with each small increase in fluoride found in kids’ urine associated with a decrease of 1.63 IQ points (Fluoride Exposure and Children’s IQ Scores: A Systematic Review and Meta-Analysis).
Cont….
Did a quick ChatGPT AI search and came up with this to ponder.
Here’s a structured summary of longitudinal evidence on fluoride in drinking water, addressing its benefits to teeth and potential neurologic/health concerns, especially in children:
⸻
🦷 1. Dental Benefits (Longitudinal/Population Data)
• Grand Rapids Trial & early US/Canada trials (~1945–1960s): Communities with fluoridated water showed 48–70% reduction in cavities among 12–14‑year-olds after 13–15 years of fluoridation  .
• Australian adult cohorts (pre‑1960 vs 1960–1990 lifelong exposure):
Adults with >75% lifetime fluoridated water exposure had 10–11% fewer decayed, missing, and filled teeth (DMF‑Teeth) and 21–30% fewer DF‑Surfaces than those with <25% exposure .
• Danish 10‑year registry study (5‑ and 15‑year-olds): Demonstrated a significant negative association between fluoride concentration and dental caries across large cohorts .
• Cochrane 2015 review: Concluded community water fluoridation yields a 35% reduction in baby‑tooth decay and 26% reduction in permanent‑tooth decay when other fluoride sources are not available .
• CDC 2024 statement: Reviews 2.25 fewer decayed teeth per child and ~25% fewer cavities in adults and children due to fluoridation .
⸻
⚠️ 2. Adverse Dental Effects – Fluorosis
• NHANES data (US children 6–15 years): Fluorosis prevalence rose from 23% in 2004 to 68–87% by 2013–2016; primarily mild fluorosis, with minimal impact on appearance or quality of life .
• Systematic reviews confirm a correlation between high fluoride intake (≥6 mg /L) and dental fluorosis/fluoride-related bone effects .
⸻
🧠 3. Neurologic & Neurodevelopmental Effects
3.1 Cognition (IQ and Neurotoxicity)
• Meta‑analysis of 33 studies: Across various exposure types, high fluoride exposure correlated with −4.68 IQ points (−5.60 for water-specific exposure). IQ decreased by ~3 IQ points per 1 mg /L increase, particularly above 1 mg /L. Note: studies with low risk of bias did not show adverse effects .
• DARE 2020 meta-analysis: Found a standardized mean difference in intelligence of −0.29 to −0.45 SD in children; higher fluoride exposure doubled the risk of scoring low on CRT-RC (cognitive test) .
• 2024–2025 U.S. govt & JAMA Pediatrics summary:
• HHS 2024 report: Water >1.5 mg/L linked to lower IQ; below that, data are inconclusive.
• JAMA Pediatric meta‐analysis: Each 1 mg/L urinary fluoride rise correlates with a ~1.14–1.63 IQ point drop .
3.2 ADHD / Behavioral Disorders
• NTP systematic review (2022):
• Four studies (US, Canada, China, Mexico): Significant positive association between fluoride and ADHD/learning disabilities. Examples include:
• In Canada, a >6‑fold higher odds of ADHD per 1 mg/L increase in tap‑water fluoride, and +0.31 points in hyperactivity/inattention scales .
3.3 IQ in Developed Countries
• Australian longitudinal study of early exposure: No difference in IQ, emotional/behavioral development, or executive function between children exposed or unexposed to fluoridated water . This aligns with other major reviews (NHMRC 2017, Guth 2020).
⸻
📊 4. Contextual Summary
Domain Benefit / Risk Magnitude / Quality
Dental caries prevention ≈25–60% reduction Strong evidence from longitudinal trials and reviews
Dental fluorosis Mild cases common (20–40%) Severe cases very rare
Lower IQ −1 to −5 IQ points per 1 mg/L Mostly in studies ≥1 mg/L, with bias concerns
ADHD risk Increased odds (OR ~6) Limited but statistically significant studies
Behavioral/Executive Effects None observed in robust Australian cohort Reinforced by systematic reviews
⸻
🧾 5. Conclusions & Considerations
1. Dental benefits of fluoride are well-supported over decades of longitudinal, population-wide data.
2. Mild dental fluorosis is the most common non-toxic adverse effect; cosmetic concern only.
3. Neurologic concerns—dropped IQ and ADHD risk—appear in many studies at higher fluoride exposures (≥1 mg/L), especially in developing countries. However, some high-quality, low‑bias studies found no negative impact at CDC‑recommended levels (0.7 mg/L).
4. No credible evidence links fluoridation to autism, developmental delay per se, or cancer/osteosarcoma.
⸻
📌 6. Research Gaps & Recommendations
• More prospective, low-bias studies at common U.S. exposure levels (0.7 mg/L) are needed.
• Behavioral/ADHD outcomes require further longitudinal clarity.
• Review the total fluoride intake (water + toothpaste + diet) in children, especially under age 4.
⸻
✅ Sources
• Early trials & CDC data on decay reduction      
• Adult dental benefit studies
• Dental fluorosis statistics & trends 
• Cognitive neurotoxicity meta-analyses 
• ADHD/behavioral disorder links 
• Australian longitudinal null findings 
⸻
Bottom line: Community water fluoridation at recommended concentrations (0.7 mg/L) is a proven method to significantly reduce tooth decay. Mild dental fluorosis is generally cosmetic. There is suggestive evidence of neurodevelopmental effects at higher exposures, but findings are inconsistent and often confounded. Continued high‑quality studies—especially in non‑fluoridated vs fluoridated populations—are essential to resolve these concerns.
Mild dental fluorosis means that the teeth are especially resistant to decay. The "cosmetic" effect of mild fluorosis is a whitening of the teeth, though it can be spotty.
I disagreed with the argument, but I was not offended or upset. I just disagreed with the suppositions that you outlined articulately.
Don’t appease the whiners (or the loudest and squeakiest wheels). I am curious as to how many readers complained, as a fraction of your entire readership. My suspicion is it was a small minority.
Resist the temptation to be captured by your audience.
This stack is great for hosting disparate views. If people can’t handle some differences in opinion, they shouldn’t let the door hit them in their backsides.
Besides, fluoride was just one point among several made yesterday. Unless there were some pro-cholera dissenters that I missed.
This site promotes critical and independent thought. So it naturally attracts those with a contrarian lean. But the irony is that some among this cohort can’t seem to handle reading things they disagree with. (Or at least can’t disagree by making an argument about the point of disagreement, but instead wonder why they had to be exposed to something they disagree with in the first place). It’s a weird dynamic I also see at The Free Press.
Show me one scientific argument in the first post... the author didn't make a single one. She started out with the premise that the budget cuts were bad and fluoride is good. Provided no "sensible" arguments for why... no detail on the cuts or how they would link to cholera or other GI illnesses. No real reason why water is suddenly expected to become non potable.
Maybe the reason isn't that people disagree with the post but with the lack of scientific argument. VP has certainly posted items that created a lot of "uproar" but go back and read what he wrote-- it was well reasoned and had clear arguments.
This would’ve been a perfect rebuttal for you to have written about the piece in the comments section yesterday.
Me, I took it as satire, found it quite funny, and didn’t take it too seriously beyond that. YMMV.
But to read one article you disagree with, then question whether this substack as a venture is viable (as you did yesterday)? Gimme a break.