Colonic explosions: In the early days of colonoscopies, attempts to burn off polyps in the colon ignited explosive hydrogen gas in the colon of several unlucky people, sometimes with tragic results. The colon-cleansing preparations people now take the night before a colonoscopy have solved the problem. Says Levitt: "I've never heard of an explosion in someone who's had a decent prep. But until they used these prep solutions, there was a problem with explosions.''