Toxic fluorinated compounds found in drinking water of 33 states

This is analogous to why scientists and policymakers focus so much on CO2 when worrying about global warming.

Other compounds, like water vapor or methane, trap more heat than CO2. But they leave the atmosphere much more quickly: water rains out after a week or two, and methane breaks down in about a decade. But CO2 persists for many decades, perhaps even longer depending on the state of the biosphere.

So despite that fact that CO2 is harmless to human health at atmospheric concentrations, and actually beneficial to plants and some animals, the systemic harm due to its longevity can be huge.

> likewise no human died of cyanide poisoning until the 1800s AFAIK

Cassava roots (tapioca) have been killing and otherwise causing problems for humans for millennia through cyanide poisoning. Bitter almonds have been causing trouble for almost as long.

There are no official treatment recommendations for PFNA, PFOA, PFOS that I know of but they can be treated with activated carbon, RO membranes or some combination. GAC seems to be pretty effective and you could feel pretty safe with a Brita filter, a multi-stage undersink system or a large whole house filter.

The issue with chemicals like these and treatment is that without extensive testing there isn't much information about breakthrough rate and contact time and the relationship, so repeated testing is really the only way to know when you need to change media.

Manufacture cartridge change recommendations generally are pegged to chlorine removal only, so a filter may deplete it's PFOA removal potential in a 1/10 the recommended change interval.

This EPA page seems to imply that activated carbon would help remove it:

https://www.epa.gov/ground-water-and-drinking-water/drinking...

---------------- Can PFOA and/or PFOS be boiled out of my water?

No; PFOA and PFOS cannot be removed by heating or boiling water. However, there are steps you and your drinking water system can take to limit your exposure.In some cases, drinking water systems may be able to reduce concentrations of perfluoroalkyl substances, including PFOA and PFOS, by closing contaminated wells or changing rates of blending of water sources. Alternatively, public water systems can treat source water with activated carbon or high pressure membrane systems (e.g., reverse osmosis) to remove PFOA and PFOS from drinking water. These treatment systems are used by some public water systems today, but should be carefully designed and maintained to ensure that they are effective for treating PFOA and PFOS. In some communities, entities have provided bottled water to consumers while steps to reduce or remove PFOS or PFOA from drinking water or to establish a new water supply are completed.

Home drinking water treatment units are typically certified by independent third party organizations against ANSI (American National Standards Institute) standards to verify their contaminant removal claims. Some home filters remove impurities using activated carbon and reverse osmosis, which are the same technologies utilized by public water supply systems to remove PFOA and PFOS. However, there currently are no ANSI protocols for testing home treatment systems to verify that these devices effectively remove PFOA and PFOS or how frequently the filters should be changed in order to maintain removal efficiency. NSF International is currently developing such protocols.

I tried to find some data on that, but it appears that there is no data available showing definite health hazards of these compounds.

Getting such data can be difficult. Animal models can often be wrong: the toxicity may be specific to humans, or the damage may require exposure over time frames than the animals' life span, or it only manifests under rare circumstances (i. e. interactions with drugs).

The best data you can get may be from people who were exposed to the compounds unusually high degrees, usually because they worked with them. But that group of people may be too small, or not diverse enough (we've long avoided exposing pregnant women to industrial chemicals), or the nature of their work exposed them to different chemicals muddling any results.

You say "Its irresponsible to make policy decisions without knowing the actual risk level", but I'd say that you can't not make a decision: taking the view that a chemical is safe until proven otherwise is as much a decision as the opposite. The EU has started to assume new compounds to be dangerous until proven otherwise – I believe the US may still be doing the opposite.

Ethanol (i. e. alcohol) is also a particularly bad unit of measurement, considering its effects on human health are not just somewhat disputed, but apparently highly unusual. There is quite a lot of evidence for beneficial effects of alcohol, possibly even at rather high dosages (although the effects on cancer, which you mention specifically, are probably closer to a standard linear dose-response relationship,)