When Sophia Huston started working as a hotshot — a specialized wildland firefighter with advanced technical training — she was 19 and didn’t know what she was getting herself into. She was physically fit and worked out regularly, but she wasn’t ready for preseason training, when the U.S. Forest Service, the agency she worked for, weeds out the unprepared with intense and physically demanding drills. “You’re going on hikes with full gear and chainsaws,” she said. “I weigh about 115 pounds and I’m carrying about upwards of 80 pounds of gear up a hill. I’m feeling the stress on my body and joints. I’m waking up in the middle of the night to eat food because I can’t get enough calories in.”

Shortly after the training began, Huston got what would be her last menstrual cycle of the fire season. She’s been working in fire for six years now and hasn’t gotten her period for the past three years, which she speculates is due to lack of sleep, poor quality of food, and the physical strain of the job. She doesn’t know what the long-term repercussions of working in the fire service are on her health and fertility. “I just know it’s not good for you,” she said. “It’s not very conducive to fertility and reproductive health.” New research suggests that Huston’s hunch is spot-on.

Smoke, heat, fire-suppressing chemicals, and the physical exertion required to put out and control fires all have effects on humans, but the body of published research on how firefighting affects health is astonishingly small. Studies have shown that being exposed to smoke in general is linked to lung cancer and cardiovascular disease. But little is known about the cumulative impacts of fighting fires year after year, whether soot and other compounds can get absorbed through the skin and cause health problems, and how, exactly, smoke impacts the body in the long-term.

The ways in which fighting fire, and fire itself, affect women are even less understood. Women make up a tiny fraction of the national fire service, both in structural fire departments — the local departments that put out house fires — and the wildland crews that fight fires that occur in the wilderness and areas where wildland meets urban zones. They operate in a system that was built for and around men. And despite evidence that even short-term smoke exposure can affect pregnancy outcomes, female firefighters receive little to no information from their employers on how fire could impact fertility or pregnancy. “Nobody says, ‘smoke is bad, don’t stand there,’” Megan Saylors, a career wildland firefighter for a federal agency, told Grist. “It’s just such an accepted part of our work environment.”

Read the full article about reproductive health problems for female firefighters by Zoya Teirstein at Grist.