On a drizzly afternoon in 2013, Duke University undergrads pitched their tents to wait in line for a basketball game, and Heather Stapleton saw an opportunity.

An associate professor of environmental health, Stapleton headed out with some of her students to answer a question. Mounting evidence linked flame retardants—used in everything from couches and carpets to televisions and baby clothes—to a host of health problems, including cancer, impeded childhood development, and reproductive complications. Stapleton had noticed safety tags on camping tents that warned consumers they were also treated with flame retardants, but she wanted to know: Which chemicals were being used? And do those treatments drift off rainflies to be inhaled by campers bundled in mummy bags, or do they linger on fingers to be swallowed along with handfuls of trail mix?

“It was basically out of my curiosity,” she says. Offering food as a trade, Stapleton and her students convinced queuing basketball fans to let them wipe cotton swabs over their tents and hands. Back in the lab, the researchers found a number of chemicals on the cotton swabs, including problematic ones like polybrominated diphenyl ethers (PBDEs) and tris (1,3-dichloroisopropyl) phosphate (TDCPP). Traces of those treatments had indeed been left on students’ skin.

Stapleton’s initial findings prompted Duke University graduate student Genna Heath (then Gomes) to focus her master’s research on the issue; she published her results in 2016. Heath and her research partner, Peyton Ward, hauled two-person backpacking tents donated by Mountain Hardwear, REI, and MSR to the university quad, where they offered passing students $20 to set them up. Wipes run over the students’ hands came back with flame-retardant levels 29 times higher after handling a tent than before. Air samples also picked up particles inside the tents. In sum: the flame retardants were leaching from the products during normal use.

Stapleton’s and Heath’s research, as well as related studies by others, have prompted tent manufacturers to reassess their approach to treating tents for flame resistance and to review the related regulations: are these treatments even really necessary? This spring, Mountain Hardwear took it one step further; all of the company’s tents are now free of flame retardants. The results, the company says, even make way for stronger and longer-lasting tents. In September, REI also announced plans to transition away from flame-retardant finishes starting in fall 2020.

Cooking on a grill creates crusty black bits that can increase cancer risk when you ingest them. So can smoking. Still, people do both, Stapleton points out. But the point is that people get to decide whether to barbecue meat or smoke a cigarette. With tents, she says, “[People] don’t have the option to look for an alternative if they wanted to make that choice, and I think that’s a problem.”

Her 2013 research found flame-retardant additives on ten of 11 tent fabric samples tested. That data point suggests mosts tents for sale in the United States are coated with some kind of flame retardant, but consumers are hard-pressed to find a more comprehensive review. (No one I spoke to in the course of reporting this story knew what percentage of tents are treated.) Laws only require brands to disclose that the tents were treated to meet a rule drafted by the Industrial Fabrics Association International, originally called Canvas Products Association International. What exact treatment and whether it’s from the list of problematic chemicals isn’t publicly available.

In sum: the flame retardants were leaching from the products during normal use.

No federal laws require these treatments. In the 1970s, the Canvas Products Association International wrote a flammability standard, CPAI-84, that has become the default standard for most tent makers, but it hasn’t been updated in more than 20 years. It was written for waxed or oiled cotton tents, like those hoisted for big-top circuses, and calls for holding a flame to fabric for 12 seconds without it igniting. Just four states mandate it, including California (Canada does as well), but the Golden State’s purchasing power means the vast majority of tents sold in the United States comply. (California’s laws also require that manufacturers label tents as containing materials that can cause cancer.)

Many tent makers have purged the worst known offenders, but there are hundreds, if not thousands, of individual formulations of flame retardants, Heath says, and the list of options grows faster than research on their health effects can keep pace. In the past few years, the National Toxicology Program published studies on a newer type of flame retardant that was also found to be toxic, and Stapleton’s most recent research argues that new options are no better than their predecessors.

In March 2018, REI banned a long list of flame retardants from products sold in their stores. But keeping up with the latest research is an ongoing process. “The toxicology side is always playing catch-up to the chemical industry,” says Matthew Thurston, director of sustainability in the Division of Brand Stewardship and Impact for REI.

Fortunately, REI recruited a heavy hitter. Before Heath graduated, the retailer hired her; she’s now manager of REI’s Sustainable Materials and Innovation Program.

“Honestly, [the data so far shows that] there’s no flame retardant that is truly benign,” Heath says. “It’s usually a trade-off. If it doesn’t have carcinogens, it’s toxic to aquatic life. We tried to figure out how to choose the most benign options available, but it’s slim pickings. And a lot of the ones that rise to the top in a lot of the assessments of safer alternatives are doing so because there’s gaps in the data.”

REI recommends washing your hands after setting up a tent and sleeping with the rain fly off when possible. But how practical is that?

“In the absence of better guidance, I do wash my hands,” Heath says.

Joe Vernachio, CEO of Mountain Hardwear, laughs and calls these guidelines “ludicrous.” “It’s completely irrational to think that we should make products that people should have to wash their hands after using,” he says.

Beyond that, he’s concerned for people who make or handle these tents, like those in his warranty department. When Mountain Hardwear staff was discussing how to make their products more sustainable, they asked themselves: Did anyone present want to sleep in a tent treated with flame retardants? The answer was unanimously no.

“These chemicals are not good for anybody and really don’t do much for flame retardancy, so we’re not going to use them,” Vernachio says.

Around the world, the rules on flame retardants vary, but the number of tent fires remains low. Some credit the new synthetic fabrics now ubiquitous in tent construction, which tend to melt away from fire rather than go up in flames like cotton. Today’s tents come close to meeting flame-resistant standards—within seconds of the time-based rule—even without the chemical use. That’s why the Outdoor Industry Association (OIA), as well as some outdoor companies, aren’t convinced the CPAI-84 standard makes people safer.

Ditching flame retardants allows manufacturers to apply silicone on both sides, which gives the tents higher tear strength and longer-lasting water repellency, Devon Lambert says.

In April, the OIA released a review of the U.S. Consumer Product Safety Commission’s accident report database, analyzing incidents involving tents. The OIA filtered tents made with equivalent materials and technology, with and without flame retardant treatments, and organized the data for similar usage habits among tent owners. That review found that fires were rare—whether camping tents were treated, potentially treated, or untreated with flame-retardant chemicals. In the United States, out of 16,000 injuries in a five-year period, only 14 included a tent igniting. As the OIA quoted, “The most common ways consumers were injured were putting up or taking down a tent, tripping on tent stakes, or tent structural fails.” The report also noted that the European Union, Japan, and Australia don’t require flame retardants and yet show little difference in tent-ignition frequency—six incidents in Europe between 2008 and 2016, one fire in a decade in Japan, and five in Australia between 2011 and 2017.

“People are not getting hurt when you don’t put flame retardants in a tent,” says Terry Breaux, tent category manager at MSR. “So here’s something we just don’t need to put out in the environment.”

There’s another benefit to ditching flame retardants: better tents.

Tents are made of nylon and treated with silicone on one side and polyurethane mixed with flame retardants on the other. Ditching flame retardants allows manufacturers to apply silicone on both sides, which gives the tents higher tear strength and longer-lasting water repellency, says Devon Lambert, manager of Mountain Hardwear’s equipment product line. They may even be slightly lighter weight and have a silkier feel.

Industry pros agree that the rules requiring the chemical treatments probably curb innovation.

“There’s a few fabrics that companies have been developing that are extremely lightweight…but they can’t pass the flammability standard,” says Jessie Curry, manager of sustainable business innovation for the OIA. “It makes me curious what tents will look like if we get the standard updated.”

For now, manufacturers interested in abandoning the chemicals balance the short-term risk of fire-related liability (though Mountain Hardwear’s legal staff estimates the exposure is minimal) with the long-term, less-traceable risk of consumer exposure to toxins. Nonetheless, when Mountain Hardwear made the move, it joined Fjällräven in dropping flame-retardant treatments from its entire tent line. Nemo has some treatment-free options available but doesn’t ship them to states that require compliance with CPAI-84.

Brands like Hyperlite Mountain Gear and Zpacks have found a different workaround. Their ultralight backpacking tents use Dyneema fabrics, and because that material shrivels away from flame rather than catching fire or even dripping melting plastic, it allows them to skip chemical treatments while still passing CPAI-84.

REI worked in partnership with the OIA and officials in Canada to draft a new flammability testing method that is more relevant to modern tent materials. The new test criteria have yet to be finalized, but the latest version suggests it may focus more on how much material burns or sheds “flaming debris,” rather than how quickly tent fabric extinguishes after exposure to flame. The approach will allow REI to phase out flame retardants from its products beginning next year. According to an REI blog post on September 30, when this new testing protocol is finalized, the company hopes to use it in place of compliance with CPAI-84. Heath has suggested the new testing method could be adopted throughout the United States as an update to the old standard.

REI has indicated the phase-out will be just that—a slow transition. Company PR staff insist products will continue to meet all state regulations, but couldn't say how exactly they’ll achieve those competing goals. According to the same September blog post, brands sold in REI stores will need to “make their own decisions” on this front, provided they steer clear of flame retardants on the company’s restricted substances list. Mountain Hardwear, which sells tents in California, says it will stand behind its products if a concern arises. Local fire marshals, the parties responsible for enforcing CPAI-84, aren’t expected to make it a priority.

“It’s a trade-off that a brand has to weigh,” Curry says. “But if we do know that there’s very little risk in a tent igniting, why would we have any customers exposed to flame retardants?”

5 Flame Retardant–Free Tent Options

All Fjällräven tents, including the Abisko and Keb series, are made without flame retardants, as well as other known problematic materials, including PVC plastic and fluorocarbons. Hyperlite Mountain Gear and Zpack’s ultralight, long-distance tents use Dyneema Composite Fabrics and are free of flame retardants. All Mountain Hardwear tents released in 2019 onward—including the spring 2020 debut of the roomy two- and three-person Mineral King tent—has ditched these chemicals. Nemo’s Chogori two- and three-person mountaineering tents and Spike ultralight one-person tent are made with silicone-treated fabrics that are free from flame retardants. (They will not ship to California, Louisiana, Minnesota, or New Jersey.)