Scientific Evidence: Heavy Metals & PFAS in Tampons

In July 2024, researchers Jenni A. Shearston, Julia R. Varshavsky, and colleagues at the University of California, Berkeley published a study titled "Concentrations of metals in menstrual products" in Environment International (Volume 190, Article 108898). This peer-reviewed study represents the most comprehensive analysis of metal contamination in tampon products to date.

The researchers purchased 30 tampon products from 14 different brands at retail stores in the United States, United Kingdom, and Greece. Using inductively coupled plasma mass spectrometry (ICP-MS), they tested for the presence and concentration of 16 metals.

Key findings included the detection of lead in 100% of samples, along with varying concentrations of arsenic, cadmium, chromium, mercury, manganese, barium, cobalt, nickel, selenium, tin, thallium, vanadium, and zinc. No brand or product type (organic vs. conventional) was consistently free of metal contamination.

The vaginal mucosa is a thin, highly vascularized mucous membrane. Unlike the skin, which has a thick keratinized layer that provides a barrier to chemical absorption, the vaginal epithelium allows chemicals to pass more readily into the underlying blood vessels.

Critically, chemicals absorbed through vaginal tissue enter systemic circulation while largely bypassing first-pass hepatic metabolism — the liver's process of breaking down and filtering toxins before they reach the rest of the body. This means that metals and chemicals in tampons may reach other organs at higher effective concentrations than the same substances consumed orally.

Pharmaceutical research has long recognized this property. Vaginal drug delivery systems (such as hormone rings and antifungal suppositories) are specifically designed to exploit this absorptive capacity. The same biological mechanism that makes vaginal drug delivery effective also makes the route a potential pathway for toxic metal exposure.

In addition to heavy metals, per- and polyfluoroalkyl substances (PFAS) have been detected in tampon products through independent laboratory testing. PFAS are a class of more than 12,000 synthetic chemicals used in manufacturing for their water-resistant and non-stick properties. They are known as "forever chemicals" because they do not break down in the environment or the human body.

The EPA has linked PFAS exposure to a range of serious health effects including thyroid disease, kidney cancer, testicular cancer, immune system suppression, liver damage, reproductive harm, and developmental effects. PFAS in tampons may originate from the manufacturing process, raw materials, or contaminated water sources used in production.