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Comment by WillPostForFood | Hacker News Reader

I'm not following closely, but is this pseudoscience?

https://hsph.harvard.edu/news/fluoride-childrens-health-gran...

https://ntp.niehs.nih.gov/whatwestudy/assessments/noncancer/...

Fluoride is known to be problematic at high concentrations (hell, everything is). The problems of fluoride really start to come into play at concentrations of around 10-20mg/L, and some of the areas being studied are running well in excess of 100mg/L of fluoride.

The EPA limit for fluoride is 4mg/L. There's an argument to be made that it should be lowered to 2mg/L. When fluoride is added to drinking water, the target is around 0.9mg/L--no one's coming close to the EPA limit, and that exists because groundwater sources can end up being naturally high in fluoride. (I'm not sure what the typical natural occurrence of fluoride is in Utah, but I strongly suspect that they're not making any moves to actually remove fluoride from existing systems.)

Seems to cause problems at lower levels than that:

> The NTP monograph concluded, with moderate confidence, that higher levels of fluoride exposure, such as drinking water containing more than 1.5 milligrams of fluoride per liter, are associated with lower IQ in children.

https://ntp.niehs.nih.gov/whatwestudy/assessments/noncancer/...

Those are based on countries with much higher levels of fluoride than the USA adds.

Follow up studies have found the levels in the USA to be perfectly safe and in fact beneficial since poor people don't get dental care like they do in other countries.

Please share study that shows it is safe in the US for children. The EPA allows up to 2mg/L in water and we have some evident that 1.5mg/L has negative effects on children.

HN Comments were very credulous before the election. Shows how flexible belief in science is.

https://news.ycombinator.com/item?id=39235663

It doesn't take much to observe that we've been fluoridating municipal water for over half a century and children are doing mostly fine. It's the actions of children's parents that contribute the most to their IQ losses.

> levels in the USA to be perfectly safe

because everybody drinks the same amount of water right?

ridiculous position to argue from.

I think the argument they make is fair. The levels that the US aims to have fluorinated water concentrations. If theres a bad actor county well thats on them not the standard thats set.

I didnt look too closely, but the concentration recommended by the FDA is much lower than many of the sample sets in that linked study. Some 10 times as much. One is a hundred times as much.

Not sure if that first link was to the Harvard summary intentionally but heres the actual study: https://ehp.niehs.nih.gov/doi/10.1289/ehp.1104912

The second link showed a concentration as little 2x the US amount was impactful.

*The NTP monograph concluded, with moderate confidence, that higher levels of fluoride exposure, such as drinking water containing more than 1.5 milligrams of fluoride per liter, are associated with lower IQ in children. The NTP review was designed to evaluate total fluoride exposure from all sources and was not designed to evaluate the health effects of fluoridated drinking water alone. It is important to note that there were insufficient data to determine if the low fluoride level of 0.7 mg/L currently recommended for U.S. community water supplies has a negative effect on children’s IQ.*

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