writes in with a story about how important buying the right kind of kitty litter can be. "In February, a 55-gallon drum of radioactive waste burst open inside America's only nuclear dump, in New Mexico. Now investigators believe the cause may have been a pet store purchase gone bad. 'It was the wrong kitty litter,' says James Conca, a geochemist in Richland, Wash., who has spent decades in the nuclear waste business. It turns out there's more to cat litter than you think. It can soak up urine, but it's just as good at absorbing radioactive material. 'It actually works well both in the home litter box as well as the radiochemistry laboratory,' says Conca, who is not directly involved in the current investigation. Cat litter has been used for years to dispose of nuclear waste. Dump it into a drum of sludge and it will stabilize volatile radioactive chemicals. The litter prevents it from reacting with the environment. And this is what contractors at Los Alamos National Laboratory were doing as they packed Cold War-era waste for shipment to the dump. But at some point, they decided to make a switch, from clay to organic. 'Now that might sound nice, you're trying to be green and all that, but the organic kitty litters are organic,' says Conca. Organic litter is made of plant material, which is full of chemical compounds that can react with the nuclear waste. 'They actually are just fuel, and so they're the wrong thing to add,' he says. Investigators now believe the litter and waste caused the drum to slowly heat up 'sort of like a slow burn charcoal briquette instead of an actual bomb.' After it arrived at the dump, it burst."