Parabens are a class of widely used preservatives in cosmetic and pharmaceutical products. Chemically, they are a series of parahydroxybenzoates or esters of parahydroxybenzoic acid (also known as 4-hydroxybenzoic acid). Parabens are effective preservatives in many types of formulas.

There’s a chance that they’re harmful. Studies have shown that some parabens can mimic the activity of the hormone estrogen in the body’s cells, and while estrogenic activity is associated with certain forms of breast cancer, parabens have been found present in breast tumors.