About 2 weeks ago I noticed a real fine brown dust in the cabinet, under the sink in the bathroom. If you run your finger through it it kind of resembles soot. I cleaned it all up but noticed a few days ago that it's back! I have no idea as to what could be causing this. It literally looks like a giant dust ball has exploded in my cabinet. Someone mentioned purging pipelines but I can't find anything about dust being a result of it. Others have suggested termites or other kinds of bugs but I just don't see how it could be. With the way everything is evenly coated it looks like it would be coming from the top of the cabinet, but the only think above all the dust covered things are pipes and a sink. I am really at a loss as to what to do about this. I am really tired of cleaning this stuff up but, more importantly, am concerned it could lead to a much bigger problem. Please help!