I lost an arguement one time to a guy that was an anti-fluoride nut. My uncle was the same and so I took the pro-fluoride position as the science that he was spewing was dodgey tabloid level material.
The arguement ended with me having to admit that I hadn't looked into it closely but had assumed that it was safe because that's what everyone reasonable seemed to be saying.
Here's the paragraph from the study that made me change my viewpoint:
> Although the studies lacked sufficient detail for the committee to fully assess their quality and relevance to U.S. populations, the consistency of the results appears significant enough to warrant additional research on the effects of fluoride on intelligence.
National Academies of Sciences, Engineering, and Medicine. 2006. Fluoride in Drinking Water: A Scientific Review of EPA's Standards. Washington, DC: The National Academies Press. https://doi.org/10.17226/11571.
That's pretty strong language and when it comes to something like mass medicating a 2-3 IQ point drop population wide, with a history of claiming substances like DDT or asbestos being safe right up until the point that it isn't, I think we should err on the side of caution.
What a nice comment in this thread where others denigrate the anti-fluoride. It's like we have forgotten about Thalidomide and various disasters, and we have forgotten how to do science. Instead we are implored to "trust the science!". You show us that it is possible to question the dogma and research a topic such as this to the point of being able to reach a conclusion such as "more studies needed please thanks".
About 13 years ago I suffered an awful reaction to Cipro. I documented my symptoms and posted to reddit. I was called insane, delusional and a liar. This was in medical and science communities.
Since then, Cipro and other flouroquinolone drugs have received a 'black' label and warnings of causing tendonitis and neuropathy.
Recently, I learned about Ignaz Semmelweis who many years ago discovered that hand washing significantly reduces the risk of death from childbirth fever. When he presented this idea he was rejected by the medical community. His ideas were dismissed and he was harassed. Today, it is obviously standard procedure to wash hands.
In reality this is often still the case today. Science doesn't lie but the data and results can be manipulated especially when there is a personal and financial gain.
As the saying goes, science advances one funeral at a time.
> Science doesn't lie but
Science is a process -- a process run by fallible humans. Fallible doesn't mean just that "they[we] can make mistakes" but also that "they[we] are corruptible".
Science doesn't lie, but scientists are another story. Science is something we must all be prepared to do, not merely trust.
Also, science requires healthy skepticism. We don't agree with Einstein because his theory is cool and all -- we mostly agree with Einstein because the data mostly agrees with Einstein. And even today we're a bit skeptical of General Relativity because of problems like the galaxy rotation problem. Even today we call GR a theory, and we will never call any scientific theory a fact, always only either a theory or a discredited theory.
Medicine and science have a long ways to go to really grasp the diversity of individuals... most arguments about medicine I see online seem to include at least one side implicitly assuming that all humans must respond to the same things in the same way. Reddit is probably especially bad for that, sorry to hear it happened to you when you were looking for help.
People are diverse enough that literally everyone is going to have some what in which they are different, and respond in an extremely rare way to some medication or treatment. Hopefully they simply never end up needing and receiving the ones where that would happen.
In general, there are infinite possible rare events: rare events are extremely common, it is only specific rare events that are uncommon. People confuse this and assume that rare events are impossible.
For example, I have an awful adverse reaction to even very low doses of the supplement creatine- widely considered probably one of the safest and lowest risk supplements in existence. People will say straight to my face that the adverse reaction I had isn't possible, because research shows it is safe. Pointing out that the research was not specifically done on me does not seem to carry any weight.
I wonder if those people would literally choose to die from a medication they were obviously reacting badly to, because of a disbelief in the possibility of it occurring, even when it is occurring? I'd bet they take it seriously if it happens to them, but not to other people.
> When he presented this idea he was rejected by the medical community. His ideas were dismissed and he was harassed.
We live in an interesting world don't we.
A parallel I always think about is that basketball players who are paid literally millions could improve their freethrow% by using a granny shot [1]. They all know it. They don't care.
One thing to remember is that he didn't propose germ theory. He didn't have solid proof of what was wrong and only the observation that hand washing worked. This is shakey ground to get onto because it's how you end up with cargo cult behavior.
This “trust the science” attitude is a massive failure of science education. Science should empower people to understand things themselves so they don’t need an appeal to authority - while also setting high standards for what it really takes to have an informed opinion. Instead you get people that claim to be “pro science” that understand nothing deeply, and will attack anyone who dares to develop a deeply informed opinion on their own. If they really understood scientific thinking instead of attacking, they could ask questions to see if the person with the controversial opinion took the time to deeply understand by e.g. studying the scientific literature, or if they just believed a conspiracy meme on Facebook.
When I’ve shared controversial opinions, especially on here- I’ve been attacked and ridiculed by these people, despite citing my reasoning and evidence. If I mention I am an academic PI that is widely published and known in the field they will switch their tone- but if it is my official titles rather than a sound argument that convinces them, they don’t get science at all.
There's more to it than that, but I'm not sure what to call it- it also seems to include an absolute religion-like faith in, e.g. the absolute correctness of positions from official organizations and current scientific understanding. Even if a scientific researcher or medical doctor has an informed opinion based on new data that differs from mainstream recommendations - even when it can clearly be demonstrated that those recommendations simply haven't been updated yet for new evidence, they will attack that person also.
I used to call it 'scientism' but someone else on here in a recent argument pointed out to me that scientism really just means that you believe that science can in principle be used to understand anything if you do it correctly- which I agree with.
Credentialism is about the appeal to authority. It's true that they then dismiss authorities they don't like or agree with. There's no good name for this whole phenomenon, not yet.
A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.
1. The statue that enables these kinds of reviews has a weak evidentiary standard (specifically, preponderance). In other words: it would have been unusual for a judge to deny the request unless it was completely specious.
2. There's no particular indication, either in terms of policy or new research, that the EPA's recognized safe levels for water fluoridation are actually unsafe. From a strategic perspective, it's simpler for the courts to accept a (de facto) weaker than preponderant standard and kick the relitigation of water fluoridation to the EPA, rather than deal with an inevitable avalanche of lawsuits claiming that the truth is being suppressed. It's better (and cheaper) to just do the research again (for the Nth time).
The thing that makes me wonder is one thing about how it works: it changes how teeth grow, so there are less ridges, that seems like quite a big effect, and makes me wonder about effects on the rest of the body.
Do you have a citation for that? Fluoride’s effects at normal municipal levels are exceedingly well studied.
(These threads seem to need this said perpetually: nobody is claiming that you can drink a glass of fluoride and be perfectly fine. It’s all about dosage and uptake.)
The problem I think is that the dosage is unknown. Many foods contain high levels of fluoride that can combine with the fluoride in your water to bring you over the supposed safe level.
1. The main dietary source of extra fluoride for most people is tea.
2. There’s strong evidence that adults don’t experience detrimental effects from much higher proportions of dietary fluoride — even the most recent skeptic fodder (the NTP manuscript) finds no effect on adults at concentrations an order of magnitude greater than municipal fluoridation can provide.
Put together, it’s unlikely that the demographics most susceptible to higher doses of dietary fluoride (meaning children) are receiving those doses. But if you’re worried about your dietary fluoride intake as an adult, you should consider not drinking tea.
My understanding is that fluoride is supposed to be applied topically, not ingested (hence the poison control warnings on toothpaste packaging). I'm also curious to what extent research has been done all the other things fluoridated water is used for- bathing, cooking, pets, plants, etc.
And the perverse incentives involved make me innately distrustful- the source of the fluoride for example (per this page that has apparently been removed from cdc.gov)
Your fluoride toothpaste has much, much more fluoride in it per gram than municipally fluoridated water does. That, along with a bunch of other additives, is why it has a poison control warning.
(A typical dab of fluoridated toothpaste has roughly as much fluoride as 2L of municipally fluoridated water.)
The "it's a side product of industrial processes" argument is emotively salient for a lot of people. But it's worth noting that a lot of things are industrial side products: you presumably don't believe that bran is dangerous just because it's by-produced by milling flour.
I have seen many times this argument about children who cannot be taught that the toothpaste must not be swallowed, but I am skeptical about how many such children exist.
As a small child, I certainly did plenty of stupid things, but none was of this kind. Perhaps that was due to the fact that my parents never imposed arbitrary prohibitions, but they always explained why it would be bad to do something that was forbidden for me. So if they said that toothpaste must not be swallowed, because it is toxic, I never swallowed it.
Therefore I believe that if there exist such children who swallow toothpaste, that is entirely the fault of their parents. This is not a more normal behavior than eating stones or any other objects. Any children who are old enough to be able to wash their teeth by themselves should be old enough to know what may be eaten and what must not be eaten.
My kids ate toothpaste. At the same time I met a guy (still a friend today) who believed somewhat that fluoride was a mind-control thing. I decided I needed more mind control, so I stopped trying to get them to stop. It didn't help, however the kids seem OK today.
>Any children who are old enough to be able to wash their teeth by themselves should be old enough to know what may be eaten and what must not be eaten.
My experience has been the opposite, it’s very common for kids to try to eat everything including toothpaste. you do your best to try to teach them not to do it, and use a low/no fluoride toothpaste in the meantime.
I had a strawberry toothpaste as a child that had delicious flavor and consistency similar to other sweets. Cannot blame the parents for me eating small amounts of it on occasion. At least I'm pretty sure it was fluoride free.
I doubt it's a conscious choice. I am an adult and I avoid toothpaste with fluoride because no matter what I do, once toothpaste gets to the back of my tongue it simply falls into my throat. I would imagine that for a child without decades of swallowing food it's even harder to control or even notice.
I don’t know of any public sources suggesting that children tend to do either of those things. Anecdotally, I definitely did not eat or swallow toothpaste as a kid.
Absolutely. My older boy (3 y/o) definitely has eaten it and doesn’t quite get yet why he shouldn’t. I think the comments saying kids don’t do this or it’s the parent’s fault are from people who don’t have kids!
Fluoridated water is literally all around us in naturally occurring springs and drinking water humans have used for thousands of years. Generally speaking, we have a very good idea of what the benefits are and what our general tolerance is for fluoridated water.
That is true and that is why it is known that in the regions where the natural water has a high content in fluoride it affects negatively the bones of the humans who live there.
The reasons why adding fluoride to drinking water is extremely stupid are that there exists no evidence whatsoever that the ingested fluoride can have any beneficial effect on teeth, there exists no known mechanism through which ingested fluoride can have any beneficial effect (the enamel of the teeth does not have blood vessels), but there is ample evidence that too much ingested fluoride is harmful.
All the evidence about beneficial effects of fluoride is about the external contact between teeth and fluoride, when the fluoride ions substitute the hydroxide ions in enamel. This is a simple chemical reaction, it is not a biological reaction mediated by an enzyme.
This beneficial effect is achieved best by the use of toothpaste or mouth washes with fluoride, which can provide much more fluoride than it would be safe to ingest. It is impossible to optimize the concentration of fluoride in drinking water for a maximum effect on teeth while not being harmful after ingestion, because the amount of water that is drunk daily is variable and unpredictable.
Moreover, the fluoridated drinking water would have a much greater beneficial effect if one would keep the water in the mouth for some time before swallowing it, which nobody does, so most of the fluoride in the drinking water has no opportunity to provide any beneficial effect.
> exists no evidence whatsoever that the ingested fluoride can have any beneficial effect on teeth
This is just objectively wrong. We've known for almost a hundred years now that ingested fluoride reduces dental problems. Literally the entire reason why fluoridation of water got started was because scientists noted that in regions with higher than average naturally occurring fluoride levels in water resulted in fewer caries.
That is not evidence that ingested fluoride reduces dental problems.
When the water with fluoride is drunk, the fluoride ions come in contact with the teeth and a very small fraction of them succeed to substitute hydroxide ions in the enamel before the water is swallowed.
After the water is swallowed the only way for fluoride to reach again the teeth is when a very small fraction of the ingested fluoride exits again the body into saliva.
Both these actions, from the water while it is drunk and from saliva are extremely inefficient in comparison with the use of toothpaste with fluoride, because only a very small part of the fluoride introduced in the drinking water has the opportunity of interacting with the teeth.
When fluoride is inside the body, it does not have any beneficial effect, but it can interfere with the growth of bone tissue and it may have other less understood harmful effects. The body can deal with fluoride intakes that are not excessive, mostly by eliminating it into urine, but the fact that we can tolerate fluoride in small quantities cannot be an argument for introducing it intentionally in our bodies.
There is very strong population-scale evidence that municipal fluoridation significantly reduces the incidence of caries in children, including in developed countries with strong conventions around dental health (brushing twice a day, flossing, etc.)[1][2].
(A lot of this research comes from comparing cities/communities in Canada, since Canada is among the few countries that have gone on-again, off-again with municipal fluoridation. This in turn makes the data really strong, since there are relatively few confounding factors when comparing dental outcomes between Canadian children, versus children spread across the world.)
Of note: the research also indicates that, if the general public were to brush twice a day with fluoride toothpaste, then municipal fluoridation would probably have only a marginal effect on overall dental health outcomes. But there's no strong evidence that redirecting money away from municipal fluoridation towards dental health education would meaningfully move the needle on individual practices; to the contrary, there's strong evidence that a decent percentage of the population will never engage in baseline dental hygiene, and thus benefits disproportionately from municipal fluoridation.
"there exists no evidence whatsoever that the ingested fluoride can have any beneficial effect on teeth"
That is simply wrong. When fluoride comes into contact with developing teeth, it incorporates into the enamel crystal structure, forming fluorapatite, which is more resistant to acid attacks from bacteria that cause cavities.
As a Swede I always found it interesting we were one of the few countries which do not flouridate tap water.
Our country took a principled stance against mass-medicating the population with fluoride many decades ago, after a lot of push-back from some prominent scientists (including Arvid Carlsson, Nobel-prize recipient for his work on SSRIs).
> As a Swede I always found it interesting we were one of the few countries which do not flouridate tap water.
Wikipedia doesn't support this claim. Here are two quotes from different articles:
(1) "As of November 2012, a total of about 378 million people worldwide received artificially fluoridated water. The majority of those were in the United States. About 40 million worldwide received water that was naturally fluoridated to recommended levels.", from
https://en.wikipedia.org/wiki/Water_fluoridation#Worldwide_p...
(2) "Out of a population of about three-quarters of a billion, under 14 million people (approximately 2%) in Europe receive artificially-fluoridated water. Those people are in the UK (5,797,000), Republic of Ireland (4,780,000), Spain (4,250,000), and Serbia (300,000).
The first water fluoridation in Europe was in West Germany and Sweden in 1952, bringing fluoridated water to about 42,000 people. By mid-1962, about 1 million Europeans in 18 communities in 11 countries were receiving fluoridated water.", https://en.wikipedia.org/wiki/Water_fluoridation_by_country#...
It seems that Sweden no longer adds fluoride, but it's really besides the point since it says,
> 57.4 million people receive naturally occurring fluoridated water at or above optimal levels in countries such as Sweden, China, Sri Lanka, Finland, Zimbabwe and Gabon.[1]
I’m struggling with the exaggeration of calling mineralization as “mass medication”. Would you refer to remineralization of anything out of e.g. a desalination plant “mass medication”?
Here, if fluoride is added to water for the purpose of preventing tooth decay, then that is rather plainly a medical intervention, as the purpose is to prevent tooth decay.
Whether it is harmful or not (I have seen a Harvard study that claims to find negative effects on intelligence scores), it is a rather odd and arbitrary medical intervention. Tooth decay? Even if we accept that tooth decay deserves this degree of attention, we no longer live under conditions that motivated the original fluoridation of water when dentistry and brushing of teeth with fluoride toothpaste was not as common.
I simply fail to see justification for such a broad and heavy-handed intervention, or the cost of such an intervention.
Non-iodized salt is easily available at large quantities for a price very similar to iodized salt. A person who doesn't want to consume iodine via their salt can just choose not to buy it. It is not mass medication, because it is a choice.
Drinking water is a completely different story. You can't survive more than a few days without it, and it is being pumped straight into our homes. Bottled water is literally orders of magnitude more expensive, so it cannot be used as a suitable alternative for drinking - let alone for activities like showering and washing dishes. If the water contains fluoride, a significant portion of the population cannot make the choice to consume unadulterated water instead. They are forced to drink it.
So fluoridated water is mass medication because the alternatives are bottled or expensive, not pumped into the house, and salt is non-mass medication even though its “natural”-marketed alternatives are more expensive too. I guess milk and grains (vitamin D and folate added) are just normal non-mass medicated foods too given that they aren’t pumped into the house like water either? Or is it mass medication in the grains case because the FDA requires folic acid to be added?
> So fluoridated water is mass medication because the alternatives are bottled or expensive, not pumped into the house, and salt is non-mass medication even though its “natural”-marketed alternatives are more expensive too
Correct. You already get most of your salt intake from salt-containing foods. In most cases there is zero need to add salt to your food. You can get a 3lbs box of kosher salt for less than $4. Assuming the maximum recommended daily salt intake of 6g, if you get half of that via added salt, that's less than $0.01 / day.
Alternatives are widely available at no significant burden, so it is not mass medication.
> Or is it mass medication in the grains case because the FDA requires folic acid to be added?
Debatable because grain-free diets are possible. But I would indeed consider this a form of mass medication because it is mandatory to add it. In fact, for a long time my country explicitly forbade adding it to grains! These days it is allowed here, but of course optional.
My position is incredibly simple, actually: don't require adding random stuff to food which doesn't need to be there! It is my body, the government doesn't get to decide what I do with it. It is irrelevant whether that is helpful (like fluoridated water and folic acid almost certainly are) or harmful, they should not have that power in the first place.
I know. Not even one person has consistency. There will either be cases of ambiguity or contradiction. You're arguing against Gödel's incompleteness theorem. You're asking for something that's not possible.
I don't think so. It is supplementation, though you could make the argument that it, too, should not be mandated (these things are subject to public consensus). And indeed, you can easily buy salt that isn't iodized. The same holds for vitamin D supplementation in milk. It, too, is avoidable (though I can't see why you would go out of your way to avoid either, in general).
I don't think you can construe fluoridation as supplementation, especially given that it is not really needed, especially under current circumstances. There are also mixed studies about the health effects of consuming fluoride (I mentioned intelligence studies, but fluorosis of the bones also comes to mind). Also, you must factor in the gravity of the health concern and the efficacy of the treatment. Fluoride doesn't seem to be justified in this regard. Iodine, and even vitamin D, I would argue, are much more justifiable, and as I wrote above, more avoidable.
I would say the principle we should be working from is that such intervention must be justifiable and proportionately so. You're in a bad place if your basic argument for something is "It's not harmful". That's not a reason to institute something. The burden of justification is on those who institute things.
Except that fluoride naturally occurs in drinking water around the world. Some places have far too much. Would removing the excess amount also be "mass medication"?
Not all sunshine would be 'medication', but if a doctor recommended an extra hour in the noonday sun (or equivalent time under appropriate lamps) over a patient's baseline, that extra increment of light would be 'medication'.
Here's a question for you then: If you had drinking water that had an excessively high natural amount of fluoride that was causing medical issues, is it considered medicating to then filter that water to reduce the fluoridation? Why is it only 'adding' and not 'removing'?
As "medicating" implies addition, I'd not call such filtering "medicating", but it's definitely still be a "medical intervention", a purposeful change from the default motivated by health concerns.
I hate to cite Wikipedia as a source [1], but it looks like the majority of countries do not add fluoride to tap water (only 24 countries in total do).
But Sweden seems to have an interesting history with it indeed.
There's decent evidence that excessive fluoridation can cause developmental issues. Most advocacy around decreasing or eliminating water fluoridation comes from incorrectly extending that to the levels that are present in municipally fluoridated water, which are typically half or less than half of the generally recognized safe level.
(A good proxy for this stuff is asking anti-fluoridation advocates whether they eschew green/black tea or defluoridate their groundwater. If they don't do either, then they're almost certainly in the "precious bodily fluids" crank camp.)
Taking assurance from the fact that municipal-flouridation goes to "half or less" some "generally recognized safe level" implies that a low-concentration is enough for safety – "ensure your water's at that level, then have as much as you want!" – but that doesn't seem to be true.
It's total consumption that brings risks. Someone who drinks twice as much water at that presumed "safe" level is at more danger – as are those who might be getting extra flouride elsewhere, such as from higher tea consumption or excessive use of flouridated toothpastes.
Pre-2015, US flouridation standards used to be higher in colder climates, and lower in hotter climates, to account for the added water consumption in hotter climates. As of 2015, they guided everywhere to the originally-only-for-hotter-areas lower level, 0.7 mg/L, which is about half the levels with the decent evidence of harm.
But that could still be putting high-total-consumption people at unnecessary risk, and for a pretty-small benefit (fewer cavities) that can be obtained with non-ingesting tooth surface flouride exposure (as with toothpaste).
Any anti-flouridation advocate who relies on "their groundwater" rather than municipal taps probably does care about its natural concentration levels, and would only have to be concerned with moderate tea drinking if they're also receiving extra surprise flouride via municipal water. (A authentic concern for minimizing total consumption doesn't make any particular neurotic avoidance a good litmus test.)
> It's total consumption that brings risks. Someone who drinks twice as much water at that presumed "safe" level is at more danger – as are those who might be getting extra flouride elsewhere, such as from higher tea consumption or excessive use of flouridated toothpastes.
The safe levels are built around a model of the amount of water a human being can consume, both directly (drinking tap water) and indirectly (cooking, drinks made with tap water, etc.).
> for a pretty-small benefit (fewer cavities) that can be obtained with non-ingesting tooth surface exposure (as with toothpaste).
This pretty drastically understates the public health impact of fluoridation, and overstates how likely people are to apply elective equivalents (e.g. sufficient fluoridated toothpaste). The good news is that we have concrete numbers for these impacts[1], which consistently show that even developed areas show significant dental health improvements with municipal fluoridation.
>The safe levels are built around a model of the amount of water a human being can consume, both directly (drinking tap water) and indirectly (cooking, drinks made with tap water, etc.).
The epidemiological studies suggesting detectable harm at 1.5mg/L are from whatever amounts are actually consumed in affected areas, not some "model" of the max any person could consume.
Given the variety of human practices – preferences for packaged drinks, different food-preparation approaches, etc – the same tap levels could easily result in gigantic differences in net consumption among different individuals.
If the standard is half the "safe" level, but some people consume 4x or 10x as much tap water, & perhaps even have a higher baseline of non-tap-water flouride consumption, then some percentage N of the population could be developmentally-harmed, even at levels "safe" for "most". How high of an N should we accept for the modest benefit of fewer cavities?
Your link shows no public benefits other than less tooth decay, doesn't compare flouridation to other interventions, & doesn't weigh costs versus benefits.
If I'm reading its "DMFT Index" ("Decayed, Missing, Filled Teeth [per capita]") values right, it also shows a very modest benefit: a "DMFT" of 0.06 in flouridated areas, and 0.115 in non-flouridated areas. Roughly, instead of one cavity-affected-tooth per 17 kids, there's one cavity-affected-tooth per 9 kids.
Yes, we should try to minimize cavities, but what N% of outlier-consumption overflouridated kids should get a 5-IQ-point drop for that marginal benefit?
What if we shifted the flouridation expense into reminding kids to brush or use a flouridated rinse? What if we just paid a cash bonus to kids who manage to avoid permanent-tooth cavities through whatever interventions work? (The same funds would go to treatment/amelioration for those who wind up with decay anyway.)
> How high of an N should we accept for the modest benefit of fewer cavities?
You do realize dental issues kill people, right? If you are going to be actually honest in your argument, then you should be comparing the # of people that die as a result of poorer health outcomes as a result of dental complications versus the band of people having overexposure to fluoride especially since you immediately jump to the worst possible outcome on your end of the argument.
Yea, all the costs and benefits should be weighed!
I suspect a lot more people die over their lifetime from being -5 IQ than cavities. But, let's be sure all the effects are net-tallied – not just an unquantified hand-wavy "saves lives via dental health" with zero consideration to any stupidity or behavioral issues created.
1. You're presumably talking about the HHS review in your adjacent comment. Here's the actual monograph[1]. Notably, the review's authors consider it a "medium confidence" finding. In the NTP's taxonomy[2], that makes it a lower impact conclusion than the voluminous findings that show that fluoridation at 1.5mg/dL (much less 0.7mg/dL) has no adverse developmental effects.
2. The monograph is explicit about the limitations of its conclusions. In particular, the monograph explicitly says that it doesn't offer a quantitative account of fluoride-for-lost-IQ-points, and explicitly concludes that its findings do not address fluoridation at levels used in the US or Canada.
3. The monograph is focused on fluoridation at or above 1.5mg/dL, with extensive consideration given to much higher fluoridation levels.
As a whole, the monograph doesn't not present the cohesive, "closed case" for a relationship between municipal water fluoridation and developmental risk that you're suggesting exists. At best, it presents a body of evidence showing a moderate correlation between negative developmental effects and natural/dietary fluoride consumption at levels that are 5-10x times the level introduced in the US.
> If the standard is half the "safe" level, but some people consume 4x or 10x as much tap water, & perhaps even have a higher baseline of non-tap-water flouride consumption, then some percentage N of the population could developmentally-harmed, even at levels "safe" for "most".
First: neither your source (nor any source I'm aware of) shows developmental effects in adults, i.e. a general population sampling. Not even at extremely high naturally occurring fluoride levels.
However, even if we reduce to children, neither your source (nor any I'm aware of) shows a multiplicative effect to fluoridated water consumption. In other words: children in areas with 5mg/dL of naturally occurring fluoride appear to have blood levels that consistently correlate with that natural level, regardless of variations in dietary patterns. The parsimonious explanation for this is that fluoride doesn't bioaccumulate in soft tissues and is mostly excreted when not accumulated in teeth and bones, which research supports[3].
The TL;DR for this is that there's no positive evidence (and a lot of negative evidence) for differences in consumption during normal human activity having any effect on blood/urine fluoride levels. Baseline changes result in changes; volume does not.
(This ties in with the earlier point: you can definitely increase the amount of fluoride in your system over a point in time by, say, drinking 3 cups of green tea in a row. But children aren't doing that, and their most accessible equivalent - drinking water - is not something that they can chug liters of at a time.)
> Roughly, instead of one cavity-affected-tooth per 17 kids, there's one cavity-affected-tooth per 9 kids.
I personally wouldn't describe that kind of reduction as modest. On the city scale, that's thousands of dental procedures averted per year. Factored with differences in dental care (e.g. childhood cavities correlating with worse adult dental outcomes), and you have an expensive, easily preventable public health problem.
> What if we shifted the flouridation expense into reminding kids to brush or use a flouridated rinse?
Brushing reminders and basic dental hygiene are exceedingly well-messaged in developed countries. Despite that the problem remains, as evidenced by studies consistently showing differences between fluoridated and un-fluoridated populations with generally good dental practices[4].
I suppose we could always spend more on educating parents and children on good dental hygiene. But municipal fluoridation is cheap, effective, and most importantly pervasive: it addresses the last X% of the population that can't or won't practice good dental hygiene.
Just to note, the words "medium confidence" appear in neither the NTP monograph nor the taxonomy you referenced. They use the term "moderate confidence", which I guess has a similar meaning, but given the scale is from very low to low to moderate to high, I don't think this alleviates any of my concerns.
> the lower level, 0.7 mg/L, which is about half the levels with the decent evidence of harm.
Do you have a source for this claim?
This summary of a meta-analysis[1] says that there was only very weak evidence for measurable IQ harm in the range 8-16 mg/L, which is 10-20 times the recommended level. The highest quality studies in the meta-analysis showed no relationship at all between fluoride exposure and IQ[2].
> The long-awaited report released this week comes from the National Toxicology Program, part of the Department of Health and Human Services (HHS). It summarizes a review of studies, conducted in Canada, China, India, Iran, Pakistan and Mexico, and concludes that drinking water containing more than 1.5 milligrams of fluoride per liter is consistently associated with lower IQs in kids.
>The report did not try to quantify exactly how many IQ points might be lost at different levels of fluoride exposure. But some of the studies reviewed in the report suggested IQ was two to five points lower in children who had had higher exposures.
>Since 2015, federal health officials have recommended a fluoridation level of 0.7 milligrams per liter of water, and for five decades before the recommended upper range was 1.2. The World Health Organization has set a safe limit for fluoride in drinking water of 1.5.
Good summary. This is a good example of people making bijective errors around public health: the presence of a "safe level" does not itself imply that levels above it are unsafe; all it does is express confidence that the level itself is safe.
> (A good proxy for this stuff is asking anti-fluoridation advocates whether they eschew green/black tea or defluoridate their groundwater. If they don't do either, then they're almost certainly in the "precious bodily fluids" crank camp.)
Could be, but not necessarily. It depends on the justification given. You can choose to drink green/black tea or not, but you can't really choose where you have fluoride in your tap water, at least not practically.
That's why I included groundwater defluoridation as a criterion. But that's also why it's a proxy, not a surefire way to determine someone's crank status.
I'm sympathetic to the consent argument, on principle. But in practice people seem to have no objection to the government eliminating other degrees of choice, like drunk driving or sending your unvaccinated kids to school. So claims that municipal fluoridation at safe levels is a unique violation of consent comes across as special pleading.
To be fair, drunk driving and unvaccinated kids both have quantifiable risks to innocent bystanders. Are those really comparable to dental caries? They are not contagious.
There's a quantifiable economic risk: a society that has to spend more on addressing caries has less to spend on education, libraries, hospitals, defense, etc.
(This justification is also not novel to fluoridation: compare smoking in public places, where indirect secondhand smoke is unlikely to cause any health issues for bystanders but is still rationalizable in terms of social benefit.)
The economic argument opens the door to a lot more invasive interventions. Why not add semaglutide? It is likely that obesity costs significantly more to society than caries.
I do not like the smoking example much, either. Even if difficult to quantify, making other people breathe your smoke is obviously different than something where the consequences are guaranteed to be 100% your own (aside from the aforementioned economic argument).
For one, because we haven't done as much research on the long-term effects of semaglutide, especially on demographics it isn't current prescribed to. Fluoride, on the other hand, is well-researched.
I think there's a larger argument about invasiveness being something that we can also quantify, and intervening on obesity is more invasive than intervening on caries, as you've noted. But the research argument above is perfectly sufficient on its own.
If you don't like the smoking argument, consider enrichment/enforcement of foods (including public school foods). Iodized salt, enriched flour, fortified milk, etc.
I don't know but it doesn't pass my smell test. The rest of the world does not fluoridate their water (they would not have a financial incentive to), but we do and there are major financial incentives for us.
If its only purpose is to reduce cavities, that doesn't seem worth it to me. There are better ways then dumping a chemical to the water supply...
There are developing countries that add fluoride to their water supply. Do they all have the same financial incentives?
> There are better ways then dumping a chemical to the water supply...
Fluoride is present in many naturally occurring water sources.
Dental health is extremely important. If everyone had access to dental health care at least twice a year, then they could get all their fluoridation at the office. But that's not the case.
> What the current data shows is that there is a potential of neurotoxicity from fluoride at high levels, significantly higher than in the drinking water. But the same data shows, if anything, the managed drinking water levels are safe. Further, the best quality evidence does not show any clinical effect.
Indeed it would be bad if studies were done that way. Luckily they aren't (at least, not in mainstream health research, in the first world, in many decades). Medical ethics is a whole field, and public health in particular is really heavily scrutinized.
Sigh, the downvotes are cultural heresy (Dr Strangelove):
Ripper: Mandrake. Mandrake, have you never wondered why I drink only distilled water, or rainwater, and only pure-grain alcohol?
Mandrake: Well, it did occur to me, Jack, yes.
Ripper: Have you ever heard of a thing called fluoridation. Fluoridation of water?
Mandrake: Uh? Yes, I-I have heard of that, Jack, yes. Yes.
Ripper: Well, do you know what it is?
Mandrake: No, no I don't know what it is, no.
Ripper: Do you realize that fluoridation is the most monstrously conceived and dangerous Communist plot we have ever had to face?
This is just funny, I'm also against adding elements to drinking water. Fluoride can be added to salt brands, so that people have choice.
I don't have super strong feelings on fluoridation one way or the other. Mostly because I'm not a doctor, dentist, or scientist, so my opinion on the matter shouldn't carry much weight. My main issue is that I suspect the judge and plaintiff's reasoning about this issue are roughly on par with that of Gen Ripper.
Fluoridation or not is almost certainly not a huge impact (given that there's no obvious large scale harm and we've run a very large natural experiment). I'm worried that this is a preview for more meaningful health and science issues where unserious concerns might draw a sympathetic judge and harm public policy.
> so my opinion on the matter shouldn't carry much weight
If you ask N doctors you'll get N answers about all sorts of things. The received wisdom can be wrong. You have to at least demand that the science to back up <fill in the blank invasive public policy> is solid, and you should at least do a cursory check that it is.
I did do a cursory check. There is a broad consensus that fluoridation is at least not harmful, and that it has good dental outcomes. It is extremely well studied and we have decades of solid natural experiments because advanced nations are not in lockstep on this policy and so we have control cases.
The conversation does not need my opinion derived from surveying various Youtube channels for dissenting opinions. It, and most conversations surrounding complex technical scientific matters, does need our default position to be humble about what we actually bring to the table.
Why stop at adding fluoride? I think we should be adding small amounts of lithium to public water. The public mental health benefits could be enormous.
The US does already provide iodine supplementation, just via table salt and not water (I suspect because it's a more convenient way to deliver such supplementation)
Some of us who eat Japanese food (which is often very high in iodine, mostly from seaweeds like kombu) appreciate that we aren't forced to overdose even further!
If you eat "too much" salt you get thirsty, drink more water, piss out the salt and restore balance. The myth of salt being unhealthy was funded by snack food companies who knew that if they scared people away from adding salt to their normal meals they would still crave salt and likely turn to snack foods to satisfy that craving. Adding salt to your home cooked meals and abstaining from junk food is the healthy choice.
Salt is essential to neurological well-being. As you say, as long as your kidneys are healthy, you can have much more salt in your diet than is currently recommended. (Obviously not too much at once, as that can kill you.)
Though not Kosher salt, or most "premium" salts, or any of that Himalayan salt. Be careful that on your quest for the most gourmet salt you don't prevent your children from getting enough iodine!
It should be noted that this ruling has numerous problems from a scientific point of view, as does the NLP report that was relied on.
I'm not opposed to validating safety of anything we're doing at a significant amount like this, but I remain heavily skeptical of this case and it's conclusions. And I have concerns about the knee-jerk reactions being seen already in some communities. I know some (if not a lot) of the confusion is the media headlines, but the ruling does seem to lend itself to being reported with significant bias and misrepresentations.
> Chen, in his ruling, leans heavily on the NTP report. Even though the report points to evidence of harm only at levels more than double the 0.7 mg/L found in U.S. tap water
> Some critics have said that the research behind these conclusions is riddled with problems. ...
> “The bottom line,” said Tomar, “is that the overwhelming majority of those studies had either significant flaws or were, frankly, just not looked at through a critical eye.”
> Exposure to fluoridated water during the first 5 y of life was not associated with altered measures of child emotional and behavioral development and executive functioning.
> In boys, positive associations were observed between MUFcr and scores in cognitive domains at the age of 4. These findings are inconsistent with those from some previous studies and indicate the need for other population-based studies to confirm or overturn these results at low levels of F in CDW.
> In conclusion, based on the totality of currently available scientific evidence, the present review does not support the presumption that fluoride should be assessed as a human developmental neurotoxicant at the current exposure levels in Europe.
> ... the experimental evidence suggests that current exposure to fluoride, even for individuals with relatively high fluoride intake, is clearly below levels that lead to adverse effects in vitro or in animals.
> ... The discrepancy between experimental and epidemiological evidence may be reconciled with deficiencies inherent in most epidemiological studies
Do kids consume tap-water equally? I don't know how to check this. I'd imagine one family that cooks a lot of meals where you're just cooking in tap-water (spaghetti, etc), could end up having a lot more fluoride than a family that eats more like, rice, which absorbs a lot more water? Also dishes that involve longer cooking times where you end up reducing the tap-water more? At a population level, you might end up with increased variance in the same bounds?
In general, studies I've looked at show that even with unequal consumption, even those in the "high consumption" (and therefore probably higher fluoride ingestion) don't lead to what would be considered an excessive amount over the recommended exposure limits. Not saying it couldn't happen of course, there are outliers. Overall exposure should be considered for children.
> The probability of exceeding the UL of 7 mg fluoride per day via a normal diet was estimated to be very low in the Belgian adult population.
Note: it's hard to find studies like this that focus on kids and not adults, but except for the difficulty in getting accurate responses from kids, that shouldn't lead to a difference. However given that the upper level is lower in children, it's a much tighter window that could then be exceeded by other sources of fluoride like swallowed toothpaste or food supplements with fluoride. So caution is probably warranted.
An Irish study found no risk of excess consumption by adults or children (excepting "misuse of toothpaste"):
Last time there was a campaign against fluoridation in my town it was extremely innumerate and resorted to emotional appeals like "do you want chemicals in your water"? That has coloured, perhaps unfairly, my perception of the issue ever since.
I know you're deriding this as an invalid, small-brain appeal, but this is actually sound.
It's like that meme with the bell curve of the layperson, the midwit, and the genius. The layperson and the genius know that adding these chemicals to the water isn't worth the risk, they'll just articulate it in different ways. They might argue that adding "chemicals in your water" is not Lindy, that there's higher order unknown unknowns and risks that the layperson and the genius would rather not take. That the upsides simply aren't worth it versus the downsides.
Contrast that with the midwit who will appeal to bureaucrat-scholar "experts" and their myopic scientific studies. In this way, the sacraments of Scientism make it easy to fool the midwit, especially when midwit media apparatuses will dismiss the opposition per ad hominem as an inferior "Them" to the midwit's superior "Us".
But try convincing a midwit of that without a peer-review study!
If, in your analogy, "the genius" isn't also "the scientist", because the scientist who studies this topic is just praying to scientism instead of doing any research, then who, exactly, is your genius, and how do you know that they are, in fact, a genius?
Is it really fair to compare a chemical that maintains water free of pathogens to a chemical intended to bring about a change in the body of the consumer? I'd guess the genius and the layperson can both understand the value of chlorine in drinking water.
It costs money to provide fluoridation. Most municipal water is not consumed by people, and your grass, toliets, and showers don't need it; adult humans don't really either, it makes a more significant difference during the growth of teeth. The monetary benefit of fluoridating the public doesn't seem very big, but is fairly poorly measured. Eliminating the fluoridation budget or redirecting it towards direct dental health initiatives could be a better use of public funds. Maybe the opex isn't enough to care, but when the capital equipment for fluoridation reaches its end of life, maybe don't spend the capex to replace it.
This sort of reactionary perception against dumb people yelling about stuff is just as emotionally driven as the yelling itself. Just because someone makes a bad argument, doesn't mean the inverse position is true by default, it just means they made a bad argument. Even a blind squirrel finds a nut once in a while :)
I don't know if fluoride in the water is bad. But you cannot let yourself be driven to a position because the wrong type of people are taking the other position. That type of decision making is devoid of all logic, even though you got there by reacting against a position that was devoid of all logic. You need to get to a position by tuning the emotion out.
The number of untrue things vastly outweighs the number of true things. So the public can ignore ideas championed solely by idiots. Not because idiots are necessarily wrong, but simply because looking at random noise isn’t productive use of time.
A similar argument counters Pascal’s wager. There’s hypothetically infinite potential ways to end up in eternal suffering and for any ways to avoid it there’s the possibility that doing to opposite is in fact required. Thus the potential downside alone isn’t enough to compel action without some other reason to suspect a particular belief system is correct.
It’s pretty well established that larger entities (governments especially) will push loads of bogus theories out there to drown out the few credible ones. Idiots will be drawn to both. Your line of thinking is the exact reason they use that strategy.
Again like the parent said, you have to evaluate each issue on its own merits.
Maybe I wasn't super clear in my post, but this is my point, and I agree, tune out the noise. Actually reacting against the noise is bad, because at that point noise is causing a change in behavior. The only reasonable thing to do is to tune it out.
Water naturally contains fluoride in much of the world. So you need to look at the actual levels in drinking water not just assuming a location not adding it doesn’t approve of it.
Cost is also a real concern for much of the world.
Sure, but I take issue with "ignore ideas championed solely by idiots" as if this issue is just the fringe lunatics as opposed to 90% of the world. Multiple people are bringing up the economics / cost when countries like Norway, Belgium, Netherlands, Czechia, Italy, Switzerland, Japan, and Portugal don't fluoridate. You'd think if there was such a clear benefit / risk profile it would be unanimous. I can't take seriously arguments that it's such a big win with no risk when these very developed countries have decided against it.
Sure, that's not scientific (I haven't deep dived into the science), but it is a useful heuristic against bad science. For 50 years, the science in the US was no evidence many industrial chemicals added to food were harmful, even though they were banned in most of the EU and Japan. Lo and behold, CA finally bans them:
There are plenty of reasonable arguments against fluoridation of water that countries can fall on various sides of: lack of proper water infrastructure in the first place, moral/ethical/political arguments around mass-medication of citizens, overall net economic value for their specific populations, etc. Individuals and nations can reasonably come to different conclusions based on both data and philosophy.
'The activist groups had a growing, but highly controversial, body of scientific evidence to draw from. Scientists had long known that very high doses of fluoride can damage bones and teeth. Since the early 1990s, a modest body of scientific research has also suggested that fluoride can harm brain development, leading to measurable drops in children’s IQ. Many of those early studies, experts say, were poorly done. And some took place in communities where fluoride naturally occurs in the water at levels much higher than the 0.7 milligrams per liter that U.S. communities currently add to their tap water.
Still, the signs of negative IQ effects were consistent enough for some experts to raise questions. “More research is needed to clarify the effect of fluoride on brain chemistry and function,” a panel of experts convened on behalf of the EPA wrote in 2006.
Starting in 2015, the National Toxicology Program, an office housed within the National Institutes of Health, began preparing a major review of fluoride research — at least partly in response to a nomination from the Fluoride Action Network.
Around the same time, the government institute that houses the NTP helped fund new studies in Canada and Mexico that looked at levels of fluoride in pregnant women’s urine, and then investigated whether those levels were correlated with a drop in IQ in their offspring. The researchers found some signs of an effect.
The results concerned some environmental health researchers. “As the literature continued to accumulate, we were more and more convinced that there were no single flaws that could explain the consistency in the findings,” John Bucher, a retired NTP toxicologist and a lead author of the report, told Undark in an interview conducted late last year.
In August, after years of delays, the NTP released its final report, finding, with moderate confidence, that fluoride exposures at levels above 1.5 mg/L “are consistently associated with lower IQ in children.”'
There are serious researchers finding mixed results based on the levels, not just crunchy social media accounts.
“0.7 milligrams per liter that U.S. communities currently add to their tap water.”
“Fluoride exposure at levels above 1.5mg/L”
0.7 is less than 1.5, which really says everything here. Vitamin D toxicity is also a thing, but we supplement milk with Vitamin D because that’s a net benefit. https://en.wikipedia.org/wiki/Vitamin_D_toxicity
If research actually showed 0.7mg/L was unsafe advocates would bring that up. Instead they try and imply that studies suggest something they don’t, which should be all the justification necessary for the general public to ignore them.
Most of the world doesn't have potable water at all from their water systems, so what would be the point of adding flouride to that water if you are not even supposed to use it to brush your teeth.
> Just because someone makes a bad argument, doesn't mean the inverse position is true by default
No, but when the opposing side only ever seems to provide (and appears to entirely rely on) innumerate, scientifically illiterate, illogical, or otherwise bad arguments, at some point you have to stop listening.
I'm not sure -- I think that would depend on whether the EPA is statutorily enabled to research and issue public health determinations on water fluoridation, or whether that scope has been established indirectly via deference. But given that the statue in this case specifically enables compelling the EPA to re-conduct reviews, I don't think CD is an immediate concern.
I'm one step ahead here I think. Obviously the EPA is empowered to do the study. That's part of why they exist. However, my understanding is that if the level that the EPA sets is not precisely prescribed by law then that gives an opening to anybody to challenge that limit in the courts because Congress didn't set a definitive level and therefore the EPA overstepped its authority.
You think anti-fluoride activists are all on the right politically? I would be shocked if that were true, given that some of the most anti-vaccination people are radical leftists.
It's a bipartisan conspiracy, for sure. But I don't think the push for eliminating the Chevron Deference came meaningfully from the left, so any left-crank use of it is more opportunistic than strategic.
(I leave it open to your judgement whether it matters that it's opportunistic instead of strategic!)
Maybe not all but definitely the majority. It is an old John Birch Society talking point and Q is a direct descendant of that ideological foundation.
Libertarians (which is a polite way of saying ancaps these days) are also against it and they skew much more right than left when it comes to election politics.
I live in the US and the overwhelming majority of antivaxers I've seen here have been right wing religious fundamentalists or right wing politicians.
Anti-vaxers are mostly right wing politically these days. Not sure when that changed.
However, anti-flouride activists have always been right wing due to the LDS (Mormon) Church being the largest pusher of such resistance (at least here in the western USA).
Like RFK Jr.? He's not right wing. The left simply redefines everything so that if you disagree with them even 1%, you're a far right radical in their book.
There are LOTS of hippie types that want nothing to do with toxic waste like fluoride. I've seen some that don't even want to use mass-produced soap because it contains random chemicals.
I mentioned other cases. You are strawmanning me lol. As for prevalence, you want me to believe that the numerous people who worry about cow farts, fracking, secondhand smoke, gluten, GMOs, and non-organic food won't also be worried about toxic waste like fluoride? I think the only way they would not worry about it is because they've been told an outgroup has championed the issue.
Not really. Second hand smoke is relatively harmless unless you are stuck in a very smokey environment every day for years. Fluoridated water is hard to avoid, usually costs money to avoid, and you are exposed for your whole life. Smoke is a much more obvious toxin than fluoride because you can smell it, and it's irritating to most people at first.
Fluoride in water is completely unnecessary thanks to fluoridated toothpaste, yet we continue to add it. There are other countries, even in Europe, that don't do it out of concern for the health effects of the toxin. Yet people call it a conspiracy theory anyway...
RFK Jr. is mentally ill, he dumped a dead bear in Central Park, that doesn’t say sane to me. The fact that he is all over the place in ideology isn’t that interesting.
Hippies are more of a boomer thing, and they are aging out rapidly. You could say these things in the 80s with a straight face, but in the 2020s? The conspiracy theory crowd is firmly rooted into the right these days, which includes anti vaxism and anti fluoride.
But seriously, the LDS church was against fluoride before it was cool in the right to be against fluoride. So if we just look at them (and they have lots of influence in western states), it’s always been a right wing position.
Have you heard of a practical joke? Hunters are comfortable with dead animals and would not see a huge problem with moving a dead bear, unless it was rotting.
I think you need to actually listen to RFK Jr. He is extremely articulate, more so than even Obama I think. He is not actually anti-vax and has had every normal vaccine besides the covid vaccine. He is just very particular about the testing that should be done for medicine, and acutely aware of many misdeeds of Big Pharma. He's written multiple books and constant blogs chock full of scientific citations backing up what he thinks. Right or wrong, he understands much more about the industry than any other politician I've seen.
>Hippies are more of a boomer thing, and they are aging out rapidly. You could say these things in the 80s with a straight face, but in the 2020s? The conspiracy theory crowd is firmly rooted into the right these days, which includes anti vaxism and anti fluoride.
The modern hippie is just called a hipster. A lot of liberals constantly worry about cow farts, secondhand smoke, gluten, eating meat, and LOTS of other things that are occasionally valid. The most direct comparison you can make to the fluoride issue is fracking because both of these issues involve water contamination.
Many issues that liberals take up have some validity to them. We ought to be concerned about pollutants like fluoride in our water. However, we all know that they have some really crazy people among them. Like just the other day there were some arguing on here that car accidents are tantamount to murder, and that anyone driving a large vehicle has no legitimate reason to do it.
RFK Jr.'s long history of claiming thimerosal in vaccines cause autism:
https://archive.is/uIWaC
It's pretty clear RFJ Jr. doesn't believe things because he understands them well; he believes things simply because they are conspiracy theories, because he's a crackpot who's predisposed to believing any conspiracy theory that stumbles across his path.
edit:
Replying to your post below because we’re at the HN comment limit.
The weight of evidence is heavily against cell phone radiation causing cancer, so that you began your response with “cell phone radiation is known to cause cancer” suggests you have the same weak evidentiary standards as RFK Jr. and explains why you would find someone like him compelling.
I am quite sure that I don't know what you are talking about. Ever since they started me on Prozac, I've been too serene to worry about cavities at all!
That's true! Unlike fluoridated drinking water, fluorine gas may remain in contact with your teeth long enough, and in a high enough concentration, to be clinically significant!
I hope you understand that chlorine is literally a disinfectant that's designed to kill stuff, right? Chlorine doesn't exactly appear naturally in water: humans notice when it stinks. We use chlorine to kill lower forms of life. It's only safe when it's in a concentration that won't kill us, nor noticeably harm us. At least with chlorine, they admit that's the goal is disinfection, rather than pretending it's beneficial medicine!
I stayed with a friend in a major city and got up in the middle of the night to get a glass of water from the bathroom sink. Literally tasted/smelled like pool water. Buddy told me the next morning he has a countertop reverse osmosis purifier for that exact reason.
As someone else mentioned, that is chlorine, not fluoride. If it were me, I would test the water for free chlorine and combined chlorine. At generally accepted safe levels (4 ppm or less), chlorine has very little odor; many people cannot detect it at all. Combined chlorine, on the other hand, is the smell most people associate with poorly maintained pool water. And anything above 0 ppm combined chlorine is bad news, especially in drinking water.
FWIW, a properly maintained pool should not smell strongly of chlorine, either.
After living without utility water for several years, it's really easy to smell and taste chlorination in utility water systems. Some systems use a lot more than others, and systems I used to live with and never smelled are detectable now; could be they increased chlorination, but I think I'm no longer acclimated.
Indeed. I'd be curious to know what city this was. Most US cities have very high quality tap water, and tap water that contains levels of chlorine sufficient to smell would surely make the news.
The arguement ended with me having to admit that I hadn't looked into it closely but had assumed that it was safe because that's what everyone reasonable seemed to be saying.
Here's the paragraph from the study that made me change my viewpoint: > Although the studies lacked sufficient detail for the committee to fully assess their quality and relevance to U.S. populations, the consistency of the results appears significant enough to warrant additional research on the effects of fluoride on intelligence. National Academies of Sciences, Engineering, and Medicine. 2006. Fluoride in Drinking Water: A Scientific Review of EPA's Standards. Washington, DC: The National Academies Press. https://doi.org/10.17226/11571.
That's pretty strong language and when it comes to something like mass medicating a 2-3 IQ point drop population wide, with a history of claiming substances like DDT or asbestos being safe right up until the point that it isn't, I think we should err on the side of caution.