I’ve been wondering in this “toxic red sludge,” which inundated several Hungarian towns.

As I understand it so far, this material, sometimes known as “red mud,” comes from the Bayer process, used to extract alumina from bauxite.

One very big problem with this material is that it is extremely caustic (high pH, to the chemists out there). This would explain why people in Hungary have had chemical burns. If the material can be neutralized (with something acidic), then it might not be so problematic, but that’s a tall order after it’s been spread around so much.