 How did detectable levels of these heavy metals get into the tampons in the first place? First, they are typically made of cotton and a mixture of cotton and rayon, a semi-synthetic fiber that's made of wood pulp. Arsenic is a natural element found in soil, water, air, while lead and other heavy metals are part of the earth's crust. The chemicals, phthalate, that are in sanitary pads, panty liners, and tampons are