Chances are pretty good you've never heard of Thomas Midgley Jr., but you'd have to live under a rock to avoid hearing about one of his well-intentioned (and completely disastrous) inventions. That's because Midgley is the man behind chlorofluorocarbons (CFCs), those pesky little pollutants that are having a field day destroying the ozone layer in our atmosphere. CFCs have now been banned across much of the world, and will be fully banned in developing nations in 2010. We won't reap the benefits of this phase-out for about a century, though -- the length of time it takes for CFCs to say sayonara.
As if that wasn't enough to qualify Midgley as a public enemy, try this on for size: Midgley is also the man responsible for leaded gasoline. It's great at reducing engine knock, sure, but less great in terms of public health. A deliciously potent neurotoxin, lead causes a whole host of health problems from insomnia, seizures and hallucinations all the way up to blindness, coma and death.
Thanks to leaded gasoline and a bevy of other lead-laden products, close to 80 percent of Americans had dangerously high lead levels in their bodies in 1976 [source: Dartmouth]. Luckily -- at least for those to whom the statistic does not apply -- that number is now down to about 2 percent. (There is, however, some debate over what constitutes a dangerously high level of lead, so it's possible that what's considered safe, especially for children, is actually still a serious threat.)