1997 Toyota Tacoma Air Bags

Last year I found my truck sitting in the driveway filled with a light yellow slightly gritty dust. There were deposits on the seats, doors, dash and floor. It appeared to come from the steering column, and the only source I can imagine is the air bag canister. I spoke to the Toyota dealer and other independant garage mechanics and the told me they never heard of such a thing, but the only explanation I can imagine is that the air bag canister spontaneously discharged without deploying the air bag. The truck is obviously well used, and has a variety of rattles in the dash and maybe the steering column. The airbag warning light is not on.

The truck continues to operate normally, but the dust continues to filter out of various nooks and crannys. Toyota offered to look into the problem (not repair it) for a minimum of $200. Can you suggest another explanation, and do I have an option other than continuing to drive my truck with no air bag. (I don't intent to collide with anything in the neer future). Finally, if my assumption is correct, are there any health effects to the dust?

Thank you,
Jim Winner