Five popular tampon brands — including two advertised as organic — have detectable levels of fluorine, an indicator of the group of chemicals known as PFAS, according to a new report from Mamavation.

Partnering with EHN.org, the environmental wellness blog and community had 23 tampon products tested by a U.S. Environmental Protection Agency-certified lab and found levels of fluorine ranging from 19 parts per million, or ppm, to 28 ppm in five of the brands: Maxim Hygiene Organic Cotton Cardboard Applicator Tampons, OrganYc Complete Protection Tampons (made with organic cotton), Playtex SPORT Regular & Super Tampons, Tampax Cardboard Applicator Unscented Tampons and Up & Up (Target Brand) Regular Tampons.

EHN.org partially funded the testing and Pete Myers, chief scientist of Environmental Health Sciences, which publishes Environmental Health News, reviewed the findings.

The report comes on the heels of an EHN.org investigation on PFAS in everything from sports clothes to makeup.

Fluorine is a strong indicator of "forever chemicals" — which have been linked to everything from cancer to birth defects to lower vaccine effectiveness.