Supporters of growth promoters will point to the lack of cases in the field of cross infection or gene transfer.

BBC: Animals and antibiotics: the risks

The device is small enough to be worn under clothing, and is disposable, so risk of cross-infection from other patients is eliminated.

CNN: Health

Experts say that cross-infection to humans is still relatively rare and usually occurs where people have been in close contact with infected birds.

BBC: NEWS | Africa | Africa bird flu disaster warning

The only way to eliminate any risk of cross-infection in the aircraft cabin -- or the rapid worldwide spread of an infectious agent -- is to prevent would-be passengers who are either substantially exposed to or carrying transmissible infections from flying.

CNN: Commentary: Flu and your health on a plane

"We are very aware that while the risk of infection from insulin pen re-use is extremely small, cross-contamination from an insulin pen is possible, " Finan said.

WSJ: 2nd NY hospital warns of insulin pen infection