Canon issued a warning that EOS 650D (also sold as EOS REBEL T4i/EOS Kiss X6i) cameras manufactured between May 31st through June 15th, 2012 suffer from an issue that can cause the front rubber grips to turn white.
While Canon hasn't received any reports of injury or allergic reactions, the company warns that in rare cases skin contact with the discolored rubber may cause allergic skin reactions. Further details and free repair are available at Canon.
The front rubber grips of some units of the Canon EOS REBEL T4i Digital SLR camera (EOS 650D/EOS Kiss X6i overseas models) may change color (turn white) after a short period of time. Customer support for this phenomenon is described below.
Canon continuously strives to provide our customers with high quality, reliable products that can be used with confidence. We offer our sincerest apologies to any customers who may be inconvenienced.
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.