First, the EPA limit for public drinking water is 10mg/l (basically same as a ppm).

The limit is set to prevent blue baby syndrome, and after your baby is born and, say, a year old, you have a lot more blood and oxygen-carrying capacity.

The limit is set to 1/2 of the amount where there are no observed effects, so the data basically says below 20mg/l there is no observable blue baby syndrome.  


Just some facts for the discussion.