When firefighters like Jeff Laskowske from Albert Lea arrive at a fire, they are fully aware of the dangers they face from the flames and smoke. But Jeff and millions of other firefighters like him are exposing themselves to another deadly risk each time they show up to work — cancer.

Three years ago, Jeff was diagnosed with testicular cancer. And he isn’t alone. In Moorhead, Assistant Chief Greg Doeden was diagnosed with stomach cancer after more than 35 years with the fire department. In St. Paul, Steve Shapira was diagnosed with non-Hodgkin’s lymphoma after 17 years serving his city. And Jeff’s own fire department in Albert Lea saw three of their 16 full-time firefighters develop cancer within roughly a year.

Cancer is now the leading cause of firefighter line-of-duty deaths in the United States, according to the International Association of Firefighters. In 2013, researchers studying 30,000 firefighters in three U.S. cities found that the risk of lung cancer increased as the number of fires fought increased. In fact, firefighters are two and a half times more likely to develop cancer than civilians.

That’s likely because firefighters today face exposure to a more harmful range of toxins than ever before. Structures and homes are now made and filled with much different materials than they were 100, or even 50, years ago. Buildings aren’t just made of wood, glass, and metal anymore — they’re loaded with electronic devices like laptops and TVs.

These materials have changed the nature of home, building and car fires. Firefighters are exposed to these fumes and carcinogens every time they enter a fire. And even after a fire has been put out, black soot and chemicals can stick to gear, lengthening exposure to toxins and increasing the potential for illness.

Research has shown a strong connection between firefighting and an increased risk for several major cancers, including testicular, stomach, multiple myeloma and brain cancers. As these patterns emerge, we need to take action.

That’s why I joined with my colleagues to introduce the bipartisan Firefighter Cancer Registry Act, which was signed into law in early July. Our bill will establish a national cancer registry to collect and track cancer cases in career and volunteer firefighters. Health care professionals will be required to submit medical information related to cancer incidences among firefighters and make data available to public health researchers. The registry is the only way we can truly figure out what building materials are causing cancer, if certain regions have greater numbers of cases, and what precautions and safeguards will prevent more diagnoses.

When I visited the Albert Lea Fire Department last month to meet with Jeff and his team of firefighters, I got to tour their station and learn about the steps they’re already taking to prevent exposure to toxins and minimize cancer risks. As the link between cancer and firefighting is becoming better known, fire departments like Albert Lea’s are taking safety into their own hands and implementing procedures to protect themselves.

Jeff also told me his good news — he is officially cancer free.

In taking their oath, our firefighters accept an immense responsibility — to put service before self, no matter the hour or challenge. We owe it to them to study the dangerous link between fighting fires and developing cancer and to find ways to prevent it.

I am so thankful to the men and women of our country’s fire departments for their bravery and am hopeful the Firefighter Cancer Registry Act will help give us the tools to support the people who risk their lives for us.

Democrat Amy Klobuchar represents Minnesota in the U.S. Senate.