For almost two years, the residents -- and more alarmingly, children -- of Flint, Michigan, were exposed to dangerously high levels of lead via the city's tap water.

And were it not for the heroic actions of one passionate pediatrician -- who side-stepped the bureaucracy and made a startling discovery -- the poisoning, which is likely to have devastating long-term consequences, almost certainly would have continued.

Dr. Mona Hanna-Attisha , the 39-year-old whistleblower and director of the pediatric residency program at the Hurley Medical Center in Flint, says what she's gone through over the last several months has "shattered " her trust in government.

"This poisoning of an entire population was entirely preventable ," she told The Huffington Post.