Mar 11, 2011 — Airlines in the U.S. have disabled oxygen generators located in all commercial aircraft lavatories in order to remove what the Federal Aviation Administration (FAA) and other federal agencies identified as a potential safety and security vulnerability. The FAA revealed the concern about this threat on Thursday (3/10) at the same time it said airlines have already completed the work necessary to fix the problem.
Presumably the FAA feels these oxygen generators could be manipulated and exploited by someone wishing to do harm to an aircraft.
(FAA) "Had the FAA publicized the existence of this security vulnerability prior to airlines fixing it, thousands of planes across the U.S. and the safety of passengers could have been at risk. This proactive measure will help keep travelers as safe and secure as possible."
Source: Planet Data