How can I disinfect my garbage disposal?

Well, lemon isn't going to disinfect it, but it'll help keep it smelling fresh.

Try putting a cup of bleach in a bucket of water, and slowly pouring that down your drain. Let that all sit in there for about 20 minutes, chase that will a kettle of boiling water, and then chase that with some more water.

perhaps some baking soda?

Baking soda for 15 minutes; then pour the kettle of boiling water. I also use that for brown gunk that collects around stoppers in bathroom sinks - well and septic here and hard water. There is always something lurking in the pipes. I use the lemon trick also. (I am not a fan of bleach for anything, having had cancer).

is bleach known for causing cancer?

do you let the disposal run while you pour in the boiling water?

On bleach and cancer:

http://www.ecomall.com/greenshopping/bcag.htm

("Organochlorines" apparently increase the risk of breast cancer -- although not all Organochlorines are dangerous -- Claritin is an example of a drug that is an organochlorine)

On running the disposal? Yes, during the boiling water, No if you're putting anything caustic (like bleach) down there.

As a breast cancer survivor, I take undue caution, perhaps, but life w/o bleach is possible. There are intimations of its fumes being a bad thing to inhale, even for the healthy, given all the other nasty things now in the air and our bodies. So I swim in lakes and ponds and not pools. No hardship there.

you can also try vinegar for a non-bleach solution ... realsimple.com has a 101 extraordinary uses for ordinary things article that talks about garbage disposals ... you can try searching that site for "clean garbage disposal"

I understand wanting a garbage disposal to smell fresh, but why disinfect it? Is their much of possibility of germs spreading to an area that could cause problems?