#4. Popcorn Lung

A rare, life-threatening lung disease that can be caused by inhaling diacetyl, a chemical used in butter flavoring. It's normally not a problem if a) you don't work in a microwave-popcorn factory or b)you're not Colorado resident Wayne Watson, who ate approximately two bags of microwave popcorn a day for 10 years and became the first-known consumer to develop the disease. In September, as word of Watson's condition prompted the FDA to investigate diacetyl, ConAgra — the nation's largest microwave-popcorn produce — vowed to remove the food additive from its products.