Butylated hydroxyanisole or BHA is used as a preservative in many cosmetics and shampoos. BHA can increase sensitivity to the sun’s damaging rays. The National Toxicology Program, from the Department of Health and Human Services, states that BHA is “reasonably anticipated to be a carcinogen” but only when in high concentrations. Either way don’t take changes. Instead use a natural shampoo bar that is sure to be free of BHA.