"A REVOLUTIONARY and superior bat with the widest sweet spot ever." So says the marketing blurb on the Easton Stealth Comp CNT baseball bat. I'm shopping for a lightweight bat for my 9-year-old son, and the Easton seems to hit the mark. CNT, you see, stands for carbon nanotubes, and it is this artificial material embedded in the bat that makes it super-stiff yet ultra-light, perfect for my budding Babe Ruth.

The "nano" raises a nagging doubt, though. I've read news reports that suggest carbon nanotubes may be harmful. But if they are in consumer products, surely they've been tested and verified as safe - haven't they?

Carbon nanotubes are just one example of a whole range of new manufactured materials, collectively known as "nanomaterials", that are starting to be used in everyday products. The US National Nanotechnology Initiative defines a nanomaterial as a substance that has at least one ...