What should I do with an old smoke detector?
A smoke ionization detector can be returned to the manufacturer for proper disposal or you can legally dispose of it in the regular trash. 

Manufacturers of smoke detectors are mandated by the Nuclear Regulatory law 10 CFR 32.27 to see that the radioactive waste is disposed at a nuclear waste disposal facility.

When sending back a smoke detector, do not take it apart. Return the entire smoke detector by ground mail (not air mail). Before shipping, remove the batteries and place them in the trash. No special packaging is needed for your smoke detector. Just put it in a box, maybe with some newspaper for padding, and send it. You must call the company before sending.

Kidde/Firex	(800) 880-6788
First Alert/BRK	(800) 323-9005 ext. 2
Honeywell	(800) 328-5111 ext. 4
Sears	(617) 252-3500
USI Electric/Universal	(800) 390-4321 ext. 238

If you are unable to return a smoke detector to the manufacturer, place it in the regular garbage for disposal. Smoke detectors are not accepted in the hazardous waste disposal program.