For years, there has been controversy surrounding the chemical tert-butylhydroquinone (TBHQ). Currently, it is in many food products as an antioxidant. Essentially, its function is to extend the shelf life of certain foods. Robert Freeborn, a toxicologist at Michigan State University, recently carried out a study that looked at its effects on the flu vaccine. The results were cause for worry for anyone who has received the shot.