For months we have been trying to locate the source of a "dead rat" smell in our home. My husband has crawled around in the attic on numerous occasions, even disconnecting air conditioning vents to check them. The smell is always worse during the afternoon and evening. We never notice it first thing in the morning. It is also mostly in our daughters' bedrooms and the laundry room. Today while changing light bulbs in our daughters' bedrooms he noticed the smell on his hands. He tore away a little of what looks like insulation from part of the fixture and it smelled horrible! We think this must be the source of the smell. It must smell worse later in the day because the lights have been on. My question is, "Is this toxic?"