I think you should take them to the same place you take your used batteries (AA, AAA, C, D, etc....) Even though the levels of mercury have been drastically reduced in the past decade, they still contain it. Even with the miniscule amount they now possess, multiply that by two billion, (the average amount of household battieries sold in a year) it adds up to a lot.

This is, of course, assuming that you don't use rechargeable battieries. If this is the case, I apologize for the assumption.

Stumpy

Here is a link that might be useful: EPA battery facts sheet