No they don't. I am not aware of any evidence to support this (including the revised claim that smoke detectors emit radiation).
Obviously that's what Big Phire and the lame stream media want you to think. People who do their own research know otherwise.
Most likely, big pharma stands to make more money if smoke detectors were not used. Smoke detectors most often result in people leaving their house unscathed, not requiring any medical treatment.