2. They may contain cancer-causing compounds.
Most tampons and sanitary pads contain chlorine-bleached cotton and rayon. This bleaching process creates a byproduct called dioxin, which is a known cancer-causing agent. A study in Environmental Health Perspectives found low levels of dioxin in four brands of tampons, and a report released by the U.S. Environmental Protection Agency in 2012 found that dioxin could have potentially serious health implications, including infertility and pregnancy complications at even ultra-low levels of exposure.