Hi Doctors, I will keep my question short, but it is a different one. I had 2 exposures with csw's over the last year, got tested with DNA PCR with antibody at 1.5 months and 3 months. Also tested Oraquick saliva test at 4 months all negative. My questions is that I am a chemist and I work in a pharma lab, would you be aware of any chemicals that I may be exposed to that would cause these tests to be false negatives? Thank you for your time.