Le Creuset question
It is very likely that Le Creuset has changed (improuved) their enamel
...over the years. Not only have some colorants changed, but some have been eliminated by environmental legislation. The only danger in using your worn out Le Creuset is the enamel flakes already mentioned by others. I must say that in my long experience with cookware I have never seen it. Even if the enamel would be down to the cast iron there is no danger at all in using it. Some traditional cast iron was never covered with enamel and when N.A.Christensen (Copco for some) started to make cast iron cookware they included a mat black colour in the range that looked like well seasoned raw cast iron.Many people thought it was not enameled at all. Anyway, a nice way to give new live to your cookware is to refire it at a local ceramic workshop. The difficult part is to know at which temperature (Le Creuset is not making this public) so start with the lowest possible temperature : 850 degrees C. If the result is below expectation refire at 900 etc. Considering the cost of energy it is most likely that Le Creuset produces at a relatively low temperature, so do not start higher than 850.