Although it sounds contradictory, that could be a true statement.
We're constantly redefining what "high" means. Same with radiation. All these nasty things exist in nature and always have. None are human creations, and they will still be there after all of us evil humans are gone.
Where we fail as a species is allowing them to accumulate in concentrations high enough to become harmful. But just finding out you have arsenic in your water isn't in and of itself cause for concern.