What was Bruce Banner accidentally exposed to when that caused him to turn from a mild scientist into the giant, green Hulk?

Bruce Banner was exposed to gamma radiation during an experiment gone wrong. That gamma radiation exposure caused him to transform into the green Hulk whenever he gets stressed or angry. The Hulk is a brutish and violent creature, who is uncontrollable and recalls little about being "human" when he is transformed. As a result of this, he is unpredictable and extremely dangerous.

Asked by Jennifer Sinclair · Last updated 5 years ago · 106K views