In 1968 as my dad began testing his patients hair for heavy metals such as lead, mercury, cadmium, fluoride, etc., it became clear that people were toxic. In the years since, lead was removed from gasoline, mercury was removed from paint and the Safe Water Drinking Act was passed all in hopes of minimizing our exposure to poisons.
Sadly, even with these laws and our awareness of the dangers of poison we still see widespread risk of toxicity. Most recent examples include the events in Flint, Michigan (http://www.cnn.com/2016/01/11/health/toxic-tap-water-flint-michigan/), where thousands of residents were exposed to horribly unsafe levels of lead in their drinking water, and in Porter Ranch, CA where the largest natural gas leak has leached thousands of kilograms per hour in benzine containing methane. (http://www.msnbc.com/msnbc/porter-ranch-gas-leak-catastrophe-not-seen-the-bp-oil-spill)