Like many cosmetic product manufacturers, tampon brands are not required by law to disclose the ingredients in feminine care products because they are considered “trade secrets." Tampons are, however, subject to Food and Drug Administration (FDA) inspection before hitting the market.

Disputers say that the tampons don’t affect period duration. However, some OB-GYN physicians believe tampons block the natural flow of menstruation and, in turn, increase the duration of each period longer. This concern is unfounded due to a lack of research.

Another popular claim is that the chemicals in female hygiene products, such as dioxin and rayon, are making periods longer. Again, there has never been a study published to prove the claim.

How Do Tampons Work?

A tampon will absorb fluid from the core out until it’s fully saturated. A full tampon then lets fluid flow through or around it.

During normal use, the tampon sits in the middle third of the vagina. The position and location does nothing to hinder the natural menstrual flow, ensuring  that the fluid is effectively absorbed.

This means that you can use tampons every day, and every night, of your period, according to the Tampax website.

Do Tampons Contain Toxic Materials?

In summer 1998, a doctoral student circulated an email claiming manufacturers add asbestos to tampons to promote excessive bleeding in order to sell more product. The email was sent from Donna C. Boisseau, a doctoral student at the University of Colorado at Boulder, and her colleague Stephanie C. Baker.

Baker claims the email is bogus and that her name was incorrectly insinuated by the hoaxter. The email started the rumor that tampons elongate your period. It spread nationwide.

The FDA responded to the incident by saying that all industries supplied data on the design and materials of tampons before they are marketed in the U.S., and that asbestos is not an ingredient in any tampon brand.

Moreover, because tampon manufacturers are subject to FDA inspection, the agency assures women that “these inspections would likely identify any procedures that would expose tampon products to asbestos.” The FDA has removed its statement regarding the incident from their website.

However, it is not false that the body can absorb chemicals in tampons through the bloodstream. Because the vaginal walls are incredibly permeable, anything in a tampon can make it to the bloodstream, which is dangerous when we’re talking about toxin-laden cotton.

Fragrances

Fragrances in tampons may contain chemical ingredients. Because the formulas are considered trade secrets, companies don’t legally have to disclose the chemical makeup of the fragrance.

Recent product-testing by the Campaign for Safe Cosmetics found that fragrance may contain allergens, sensitizers, phthalates (a class of chemicals that has been linked to hormone disruption, which can affect development and fertility), neurotoxins and synthetic musks (which can also disrupt hormones).

According to the Campaign for Safe Cosmetics, the following chemicals were found in a recent analysis of female hygiene products.

Dioxin/Rayon

Tampons are made of cotton and rayon. Dioxin is the byproduct of the process from converting wood pulp into rayon.

Until the late 1990’s, bleaching the wood pulp resulted in traces of dioxin in tampons. That method has since been replaced with a chlorine-free bleaching process.

The FDA says that the exposure to dioxin from tampons today “is many times less than normally present in the body from other environmental sources.”

However, according to Dr. Philip Tierno, director of clinical microbiology and diagnostic immunology at the New York University Medical Center, even trace amounts of dioxin can be harmful because tampons come in contact with vaginal tissue, which is covered in permeable, mucous membranes leading directly to the reproductive organs.

Pesticides

According to the Pesticide Action Network, cotton growers use extremely hazardous pesticides. The World Health Organization has classified many cotton pesticides as “extremely or highly hazardous.”

These pesticides have been linked to infertility, neurological dysfunction and developmental defects. Pesticides are harmful to the planet and to farm workers, but do they affect women who use tampons?

Because the FDA does not require companies to test for harmful chemicals or to disclose their presence, it is still unknown. The FDA recommends that tampons be free of pesticide and herbicide residues.

Carcinogens

In 2014, Women’s Voices of the earth tested four different menstrual pads for volatile organic compounds. Three carcinogens—styrene, chloroethane and chloroform—were detected in addition to acetone and chloromethane.