The tissue in the vagina is highly absorbent—and that’s an important point when discussing the safety of menstrual products. The vaginal wall is lined with mucous membranes that are rich in blood vessels and lack the protective outer layer that skin has. This allows substances to be absorbed directly into the bloodstream without being filtered by the liver first (a process known as bypassing first-pass metabolism). That’s why medications like vaginal suppositories or hormone creams are effective—and it’s also why chemical exposure through tampons or pads is a valid concern.

So when menstrual products contain pesticide residues, dioxins, or synthetic fragrances, there is potential for those chemicals to be absorbed into the body, especially with prolonged, repeated contact.