The potential of the environment inside evacuated accelerator beam-lines for breeding microbes which are both toxic to users and possess electric or magnetic organs of strength sufficient to deflect soft charged-particle beams has been explored. Unexplained human and accelerator “long-runtime” syndromes plaguing accelerator facilities for many years can be understood from this study. We have artificially bred such organisms and demonstrated that they are the cause of these syndromes. An appropriate microbicide-impregnated antiseptic beampipe liner with good outgassing properties could alleviate the problem.