I'm not sure about the WHO or UN, but in Europe the European Commission has set "Environmental Quality Standards" for 33 priority pollutants with a proposal in play to increase this to 48 ( http://ec.europa.eu/environment/water/water-dangersub/pri_substances.htm ). I don't know how these compare to EPA "safe" levels.
Published by Mark Goodger, Hydro International - Product Engineer
I'm not sure about the WHO or UN, but in Europe the European Commission has set "Environmental Quality Standards" for 33 priority pollutants with a proposal in play to increase this to 48 ( http://ec.europa.eu/environment/water/water-dangersub/pri_substances.htm ). I don't know how these compare to EPA "safe" levels.