Not enough of us regularly floss our teeth, and even fewer think about what’s in our dental floss. But maybe we should. A new investigation by Consumer Reports and Made Safe finds some surprising and potentially harmful chemicals lurking in some of the more popular floss brands.

Some dental flosses use PFAS chemicals for a smoother glide. However, these ‘forever chemicals’ have been linked to various health issues and environmental concerns. Some flosses also contain undisclosed flavors and are made of plastic.

CR and Made Safe, a nonprofit focused on product safety and sustainability, recently analyzed ingredients in a variety of flosses.

Ten flosses either failed to disclose their ingredients, contained PFAS, or included other components linked to health concerns, posing higher risks to consumers.

Three flosses stood out as favorites because they contain safer and more sustainable ingredients.

While companies aren’t required to disclose all ingredients in dental floss, Tom’s of Maine, Dental Lace, Cocofloss, and Nudge provided CR with complete ingredients lists and confirmed they don’t intentionally add PFAS to their products.

Procter & Gamble, makers of Oral-B Glide, confirmed that their floss contains PTFE (a type of PFAS), citing its performance benefits. However, they maintain it’s safe and free of certain phased-out PFAS.

The Humble Co. provided partial information, confirming PFAS-free status but giving incomplete flavor details.

The other companies did not respond to the inquiries or did not provide answers to our questions.

For people who hate flossing with string, how about a water flosser? Water flossers, like Waterpik, work well for removing food debris. Although they may not be quite as effective as string floss at scraping away bacteria, they’re a great option for people who dislike string floss or find it difficult to use.

CR recommends choosing flosses that are coated with natural substances like beeswax or plant-based waxes. And look for floss made from biodegradable materials like silk or cotton and are either unflavored or flavored using disclosed, natural ingredients.

Remember, the best flossing method is the one you’ll use regularly.