Why am I not reacting to a "serious" heavy metal, like plutonium?

Plutonium can only be used in extremely small percentages for different products and items. As such, we test for the standard accepted level set by regulations. Much like other ingredients found in products and foods, such as pesticides, if they were to be used in 100% volume, it would cause serious illness or even death. 

Plutonium is known to be found in very small dosages and used in pacemakers and some medications.