I don't want to start a debate here, but only give another opinion. I like Sandee use "already used" dryer sheets. Once the quilt has been washed, I honestly do not smell any scent at all and have seen no problems with "chemicals". I made a larger queen for my grandson who is asthmatic (as am I) and he has never had a problem sleeping under it. It may have something to do with the brand (?), but like everything else in quilting (and life) certainly there are exceptions to the rule (both pro and con). I would make a little quilt sandwich first if you are concerned and then wash it and see what happens, but don't totally discount using the sheets without doing a little more investigation. It just seems like a way to use what we have and clog the enviornment with for a good purpose---like using telephone book pages as foundations.
Just my thoughts----again not intented to begin any kind of debate.
Happy quilting!