BHA has been shown in animal studies to cause cancer in at least 3 different species, in different organs in each species. It has also been proven to cause brain damage, upset the endocrine balance, and severe allergic reactions. The US Dept of Health and Human Service is quoted as saying that BHA is "reasonably anticipated to be a human carcinogen." BHT is stored in human fat and can be released into the body in large doses during weight loss. It has been shown to increase the risk of cancer in animal studies.
Both of these chemicals are commonly found in potato chips, chewing gum, and vegetable oils. These potential carcinogens are also found in many cosmetic products including lip balm and diaper rash cream for babies.
BHA and BHT are completely banned in Europe and cannot be used in either cosmetics or food. In North America the Cosmetic Safety Database classifies BHA as a "high risk" product and lists the following as indicated health effects:
organ system toxicity
biochemical or cellular level changes
I came upon the cosmetic information accidentally but it makes me realize that as we strive for chemical-free foods, applying these same chemicals to our skin may be equally harmful.
BHA and BHT are now on my list of products to keep OUT of my house!