President Joe Biden on Wednesday signed into law a bill expanding healthcare benefits for veterans exposed to toxic burn pits while serving in the Middle East.

The bill, entitled the Honoring our Promise to Address Comprehensive Toxics (PACT) Act, is the most notable expansion of veteran health benefits in 30 years, Biden said.

"This is the most significant law our nation has ever passed to help millions of veterans who are exposed to toxic substances during their military services," Biden said. "I was going to get this done, come hell or high water."

The president commended lawmakers in Congress for passing the bill with broad, bipartisan majorities. It passed the House 342-88 and did the same in the Senate on an 86-11 vote.

"This law is long overdue but we finally got it done together," Biden said. "And I don't want to hear the press tell me Democrats and Republicans can't work together. We got it done and we got it done together."

The legislation expands benefits and services available to veterans exposed to toxins from burn pits, which are areas as large as football fields that were used to dispose of a wide variety of waste in the Iraq and Afghanistan Wars, including metal, rubber, chemicals, paint, medical waste, petroleum products, human waste, plastics, and more.

Advocates pursued the legislation for years because the illnesses veterans would suffer from after burn pit exposure would often take years to manifest, making it hard to prove that their ailments were related to their military service.

Biden was introduced by Danielle and Brielle Robinson, the wife and daughter of the late Sgt.1st Class Heath Robinson, whose name adorns the official name of the bill. Danielle Robinson said her husband's return from a tour in Iraq became "the biggest nightmare of our lives" after he was diagnosed with Stage 4 lung cancer 10 years after coming home.

"Ours is just one story," she said. "So many military families have had to fight this terrible emotional battle. So many veterans are still battling burn pit illnesses today. Too many have succumbed to those illnesses as well."

For post-9/11 combat veterans, the bill extends the period of time they have to enroll in Veterans Affairs healthcare from five to 10 years post-discharge. For those who do not currently fall within that window, the bill creates a one-year open enrollment period. The expansions mean more veterans can enroll in VA healthcare without having to demonstrate a service-connected disability.

It also removes the burden of proof for care for 23 different conditions. The list includes 11 respiratory-related conditions, along with several forms of cancer, including reproductive cancers, melanoma, pancreatic cancer, kidney cancer, and brain cancers such as glioblastoma.

Biden invoked his late son, Beau, as he has in prior veteran contexts. Beau Biden died in 2015 at the age of 46 due to glioblastoma, an aggressive form of brain cancer the president said might have been caused by his son's exposure to a burn pit while serving as a major in the Delaware Army National Guard in the Iraq War.

"When they came home many of the fittest and best warriors that we sent to war were not the same," Biden said.

Passage of the bill came with some difficulty.

Republicans initially blocked consideration after Democrats announced the Inflation Reduction Act. They pinned their objections to a “gimmick” in the funding for the bill. 

They relented after several days of criticism from veterans groups and comedian Jon Stewart, who has championed this effort and previous efforts to secure funding for 9/11 first responders dealing with illnesses caused by their exposure to the World Trade Center wreckage.

Biden commended Stewart for his advocacy.

"What you've done, Jon, matters, and you know it does, you should know," he said. "It really, really matters. You refuse to let anybody forget. You refuse to let them forget and we owe you big, man."