Canon just released a statement saying the front rubber grips of some Canon EOS 650D DSLR cameras may cause an allergic reaction. The grips could also turn white after a short period of time, which combined with the possibility of allergies, is, uh, sort of a problem since you hold the thing to take pictures.
Here's what Canon has to say:
The front rubber grips of some EOS REBEL T4i units produced in certain lots during the sixteen-day period between May 31st through June 15th, 2012 may turn white after a short period of time. We have determined after inquiry with the rubber manufacturer and analysis, that the substance zinc bis (N,N'-dimethyldithiocarbamate) is what causes the rubber surface to turn white.
Zinc bis is not used in the production of this product. However, the quantity of rubber accelerator used in the affected production lots was slightly higher than usual. As a result the rubber grips may turn white due to a chemical reaction with the rubber accelerator and other substances. High temperature and high humidity may contribute to this condition. Zinc bis (N,N'-dimethyldithiocarbamate), which becomes deposited on the rubber surface, is created as a result of this chemical reaction.
Zinc bis is what can cause allergic skin reactions (although the chances are slim). To find out if your EOS 650D is affected, you'll have to plug in your serial number into Canon's website. You'll only need to do this if the sixth digit of the serial number is "1". I know, this sounds like an Onion piece to me too, but it's straight from the horse's mouth.