Companies that have clean room environments use 70% alcohol for decontamination
and cleaning.  From what I understand, there was an actual study done many many
years ago where different strengths of alcohols where tested for cleaning
purposes and it was found 70% alcohol was effective and was the cheapest means
to clean contaminated surfaces.

Rande Kline, HT (ASCP)
Technical Services
EM Science/BDH