No doubt it's from working with aliens...
(from today's Secrecy News)
ILLNESSES AT NATIONAL SECURITY AGENCY TO BE PROBEDOne assumes that Mulder and Scully will be investigating...
Employees of the National Security Agency seem to have a disproportionately high incidence of illnesses, prompting Congress to seek a study of the matter.
"The [defense authorization] conferees are concerned with continued reports of work related illnesses among the National Security Agency (NSA) employees at Fort Meade, Maryland. The conferees direct the Secretary of Defense to undertake an epidemiological study and health hazard evaluation related to NSA buildings at Fort
See the report language from the 2005 Defense Authorization Act here: