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,Nâ€™-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,Nâ€™-dimethyldithiocarbamate), which becomes deposited on the rubber surface, is created as a result of this chemical reaction.
Doesn’t sound too bad.
The amount of zinc bis (N,N’-dimethyldithiocarbamate) detected during our testing was minimal. While Canon has not received any reports of injury or allergic reactions, depending on oneâ€™s health and physical condition, in rare cases when this substance comes into contact with skin, allergic skin reactions* may develop. In addition, if eyes are rubbed after contact with the substance, symptoms, such as red eyes, may develop.
Allergic reactions? What’s the big deal? Well, here are possible symptoms when exposed to Zinc Bis (dimethyldithiocarbamate) according to the National Oceanic and Atmospheric Administration (NOAA):
Symptoms of exposure to this compound include irritation of the skin, nose, throat and eyes. It may also cause gastritis, reduced hemoglobin and vegetodystonia. Other symptoms include brain edema and hemorrhage. In vivo, it may be corrosive to the eyes and cause hemolysis, dystrophy of the muscle, liver and kidney damage, emphysema, local necrosis of the intestine, neural and visual disturbances, irritation of the skin and mucous membranes and dermatitis. It can also cause headache, tightness of the chest and irritation of the respiratory tract.
This compound is a skin and mucous membrane irritant. It may be absorbed through intact skin. When heated to decomposition it emits toxic fumes of carbon monoxide, carbon dioxide, sulfur oxides and nitrogen oxides.
I guess Canon doesn’t think it important to fully disclose potential health effects of Zinc Bis like brain edema and hemorrhage, liver and kidney damage, and intestinal necrosis. These are scary things. Canon’s reaction worries me: I am increasingly doubtful Japanese companies will be forthright in revealing all relevant information when it comes to possible negative effects of their products and/or services on our health and the environment. Still, on the whole Japanese companies are much better than Chinese companies.