Turning dirty diapers into . . . bicycle helmets?

Consider the disposable diaper. It's part engineering marvel, a mechanism that takes one of the most foul side effects of parenthood and absorbs it into a small, manageable, plastic-wrapped package. But it's also part environmental catastrophe.

The average baby makes nearly 6,000 diapers dirty before becoming bathroom-trained. Waste watchers estimate that 27.4 billion disposable diapers are discarded each year in the U.S., adding as much as 3.4 million tons to dumps annually.

And that's not all. Each disposable diaper contains plastics and, in many cases, toxic chemical residues that show up in paper products, such as the chlorine used to make those diapers lily white.