The difference is that today, we know these chemicals and pollutants to be harmful, and yet we still allow them to be produced on an increasing scale. Mercury,

The difference is that today, we know these chemicals and pollutants to be harmful, and yet we still allow them to be produced on an increasing scale. Mercury, arsenic, lead, natural bacteria and fungi - we didn't know these were bad when they were prevalent killers - as you point out yourself, we even thought they had medicinal properties in some cases. Nobody is going to go around today sprinkling PFOA in their daily oatmeal for its purported medicinal properties, but they might get their ground springs poisoned as the result of known and accepted runoff from a nearby plant. The environmental poisoning of today is the result of negligence and fraud rather than ignorance.