Acoustical ceiling treatments by 1989 did not contain asbestos, but very minor traces of tremolite contaminate was sometimes present with the mica or perlite (the minerals are similar). It should not be a hazard and I would personally not worry about it. If you are the cautious type, you can find out for about $25 by requesting an anlytical lab to do a polarized light microscopy (PLM) test for asbestos fiber. Testing procesure is to sample a small quantity and deliver it to lab in a baggie or film canister. Wet methods of removal are recommended to reduce dust which will contain silica anyway.