More knowledge about the cancer risks facing firefighters is sought from legislation that passed the U.S. Senate this week with unanimous support.

"With cancer becoming the leading cause of death for firefighters, we need to learn more about the cancer risks our firefighters face so we can support them if they get sick," said Sen. Amy Klobuchar, R-Minn., in a statement about the Firefighter Cancer Registry Act, which she co-sponsored.

"Right now we don't know enough to protect the people protecting us."

The bill, which was passed previously by the U.S. House and awaits President Donald Trump's signature, would require the U.S. Centers for Disease Control and Prevention to collect data about how firefighters' risk of cancer compares with the population as a whole. It would authorize $2 million in spending through fiscal year 2022.

Some evidence already is in. A 2015 National Institute for Occupational Safety and Health study of nearly 30,000 career firefighters from Chicago, Philadelphia and San Francisco found that the firefighters had a modest increase in cancer diagnoses overall (9 percent) and cancer-related deaths (14 percent) compared with what would be expected for people with similar demographic characteristics in the general population. It also found firefighters had about twice the rate of malignant mesothelioma, which is caused by asbestos, as the population at large.

George Esbensen, president of the Minnesota Firefighter Initiative as well as the chief of the Eden Prairie Fire Department, blames fire retardants for that. He charged that when fire occurs the retardants release carcinogens but do little to slow the fire's spread.

Bryan Goodman of the American Chemistry Council's North American Flame Retardant Alliance disputed that, saying, "Generalizations about products or chemicals, like flame retardants, is not the answer."

The 2015 study was limited in scope and needs to be expanded on, said Rep. Bill Pascrell, D-N.J., in a news release after the U.S. House passed the legislation in September.

The bill was led by Sen. Bob Menendez, D-N.J., in the Senate, and Pascrell and Chris Collins, R-N.Y., in the House.