(NewsNation) — Researchers have detected toxic metals, like lead and arsenic, in more than a dozen brands of tampons, according to a new study by the University of California, Berkeley.

The study’s lead author Jenni A. Shearston said in a statement that “very little research has been done to measure chemicals in tampons,” and this study is believed to be the first of its kind.

Published in the journal Environmental International, the study found “measurable concentrations” of 16 metals in 30 tampons across 14 brands.

The widely accessible brands of tampons were purchased in U.S. retail chains and online from Greece and the United Kingdom. The study did not name the tampon brands, though.

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The following metals were assessed: arsenic, barium, calcium, cadmium, cobalt, chromium, copper, iron, mercury, manganese, nickel, lead, selenium, strontium, vanadium and zinc.

Toxic metals like cadmium, lead and arsenic were found in higher concentrations, while mercury and chromium showed up less. Notably, there is no exposure level to lead considered “safe.”

“Although toxic metals are ubiquitous and we are exposed to low levels at any given time, our study clearly shows that metals are also present in menstrual products, and that women might be at higher risk for exposure using these products,” said the study’s co-author Kathrin Schilling, assistant professor at Columbia University Mailman School of Public Health.

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Though the concentration of metals changed depending on organic or non-organic material used, it didn’t matter whether the tampons were name-brand or where they were bought: “No category had consistently lower concentrations of all or most metals.”

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A majority — 52% to 86% — of people who menstruate use tampons during their periods, meaning that potential toxic exposure could impact a large portion of consumers.

Researchers are uncertain whether the metals have caused any adverse health effects in tampon users. Future studies will look at how much of these metals can be released from tampons and absorbed by the body.

“I really hope that manufacturers are required to test their products for metals, especially for toxic metals,” said Shearston. “It would be exciting to see the public call for this, or to ask for better labeling on tampons and other menstrual products.”

As for whether tampons are safe to use in the meantime, one expert told TODAY.com that consumers shouldn’t be too worried but acknowledged that more research is needed.

“This study shouldn’t be the reason we all throw out our tampons ASAP, but it is important that people decide what feels right for them,” Dr. Jennifer Lincoln, an OB-GYN in Oregon, told the outlet. “It’s important to realize what period products you use is a personal choice.”

Nexstar’s Ashleigh Jackson contributed to this report.