WASHINGTON 

President Joe Biden signed into law legislation Wednesday that significantly expands health care benefits for US veterans exposed to toxic burn pits during their military service.

The bipartisan Sergeant First Class Heath Robinson Honoring our Promise to Address Comprehensive Toxics (PACT) Act marks the "most significant expansion" of health care benefits and services for veterans exposed to toxins in more than 30 years, according to the White House.

The signing is a major accomplishment for Biden, who has prioritized the legislation during his time in office in part because he blames burn pits for the brain cancer that took the life of his son, Beau. The junior Biden died in 2015 of a brain tumor after serving in the Iraq War.

The president pointed to the fatal effects burn pits had on his son's health during an East Room signing ceremony, saying Beau experienced "headaches, numbness, dizziness" before being diagnosed with the ultimately fatal cancer. The PACT Act, he said, is the "least we can do for the countless men and women" who "suffered toxic exposure while serving their country."

"To us and to many of you in the room, if not all of you, it is personal," Biden said in a room filled with veterans' group leaders and the families of those who are afflicted or died from illnesses caused by exposure to toxins.

"This new law matters. It matters a lot. It matters a great deal because these conditions have already taken such a toll on the veterans and their families," he added.

In addition to expanding health care eligibility for veterans potentially affected by toxic exposure, the act makes it easier for veterans to receive services and it removes the burden of proof for veterans diagnosed with 23 conditions linked to burn pits, including respiratory illnesses and cancers. ​​​​​​​