Have been looking into this issue as of late. Here are 2 references to share.
These studies apply to 'regular' office computer use and not with respect to multiple GPUs/VRMs/ICs running at 80 degrees C 24/7. Therefore, the concentrations of volatile compounds are likely going to be much higher from a rig.
I know many folks also espouse the use of rigs as a heat source in the winter. This only further exacerbates the condition due to lack of ventilation in cold weather.
http://www.arb.ca.gov/research/seminars/mckone/mckone.pdfhttp://www.ncbi.nlm.nih.gov/m/pubmed/15104785/TL;DR: Use your own judgement but substantial off gassing from computers was identified (not a surprise). Health impact from exposure to said compounds are unknown, especially with respect to long term/chronic effects. Assess your own risk, but a few coins probably isn't worth any risk of degradation to your health. Consider moving rigs out of regular living areas. At least try to get it out of bedrooms.
