The chemical was used by the U.S. military while the Arizona senator served in Vietnam. It has been linked to the glioblastoma cancer suffered by many veterans.

When the news broke last week that Sen. John McCain has glioblastoma multiforme, a deadly brain cancer, the nation quickly rallied around the 80-year-old politician and Vietnam War veteran.

Joy Patterson was deeply saddened by the news. Her husband, Kenneth Patterson, also served in Vietnam and was also diagnosed with glioblastoma (GBM).

“I believe Senator McCain will not survive, sadly, just as our husbands who have gone before,” said Patterson, whose husband died of the disease in 1996.

She now works to help other widows of Vietnam War veterans get their disability benefits from the Department of Veterans Affairs (VA).

The question on Patterson’s mind and the minds of so many of these war widows is:

Did Sen. McCain get glioblastoma from exposure to Agent Orange?

Agent Orange, the toxic herbicide developed by Monsanto and Dow, was sprayed by the Department of Defense over wide swaths of Vietnam from 1961 to 1972 as part of Operation Ranch Hand.

The idea was to flush out the enemy and wipe out their food supply.

But the plan profoundly backfired. The chemical has harmed or caused the deaths of thousands of U.S. troops and Vietnamese civilians.

And as Healthline reported last year, the effects are still wreaking havoc more than 50 years later.

The VA has stated that nearly 3 million U.S. veterans who set foot in Vietnam from 1962 to 1975 were exposed to dioxin-contaminated herbicides, including Agent Orange.

Multiple sources interviewed for this story, including scientists, physicians, veteran advocates, veteran attorneys, and veterans and their family members, believe it’s likely McCain’s glioblastoma is the result of exposure to Agent Orange.

It’s taken decades and a lot of blood, sweat, and tears among the Vietnam veteran community to get to the point in 2017 where multiple diseases are now finally presumed to be caused by exposure to Agent Orange

The list now includes prostate cancer, non-Hodgkin’s lymphoma, multiple myeloma, Parkinson’s disease, and ischemic heart disease.

GBM is not on the presumptive list, but there’s a growing consensus among neuro-oncologists and other experts outside the VA that it should be.

Angelo Venniro served in the army for 20 years and did two tours in Vietnam, where he was exposed to Agent Orange and was later diagnosed with GBM.

Writing on his behalf, Dr. Katherine Peters, assistant professor of neurology at the Preston Robert Tisch Brain Tumor Center at Duke University Medical School, said, “As a board certified neuro-oncologist and brain cancer researcher, it is my opinion that exposure to Agent Orange in Vietnam was a significant factor in causing, contributing to, or aggravating brain tumors in Vietnam veterans.”

There are thousands of examples of these so-called “nexus letters” from medical experts.

Veterans or their loved ones are required to provide these letters to the VA to even have a chance of being approved for a disability claim

McCain, a former Navy pilot who spent more than five years in the infamous Hanoi Hilton prisoner of war camp, was in Vietnam from 1967 to 1973.

Experts say Agent Orange was in the air, water, and food in Vietnam.

Claude D’Unger, an environmental scientist who has written numerous papers on environmental toxins to which America’s veterans have been exposed, said there is “virtually no way in hell that anybody in Vietnam at that time was not exposed to it.”

Robert Walsh, a veterans’ disability law attorney from Michigan who has represented thousands of veterans in their disability cases at the VA, said one of the many possible dioxin exposure scenarios for McCain was when ships pumped portable water to the aircraft carriers and other ships as part of the resupply missions.

“The water came from wells in Da Nang,” Walsh explained, “and from other ports which were tainted then and remain tainted today with dioxin from these herbicides.”

Walsh said Navy aircraft would fly missions during the Agent Orange spraying operations.

“This was not crop dusting. The C-123 spray planes stayed up higher to avoid ground fire,” Walsh said. “Naval aviation personnel have described planes on the hanger deck of the aircraft carrier literally dripping with Agent Orange slime.”

The flight crews had to wash down these aircraft, Walsh explained,

“The crews would get it on their hands and clothes, and it was very concentrated. Then they washed down the deck of the hanger with a hose. But this stuff makes a vapor, you can smell it, so you are breathing it,” Walsh said

Walsh said that he has made a case of significant exposure to Naval aviation personnel on aircraft carriers.

“And Sen. McCain was foot wet during his Vietnam service,” Walsh said.

Joe Moore, an attorney with Bergmann and Moore, a well-known law firm that represents solely veterans with disability cases before the VA, has approximately 20 GBM cases.

The firm has already won five of them, and they expect to win the rest.

But it takes time, Moore said, and the VA makes the families jump unnecessarily through hoop after hoop and forces them to relitigate the issue every time.

“The link between the defoliant and glioblastoma has been widely established outside the VA,” Moore said.

He added that if he were introduced to a veteran with GBM who’d spent as long a period of time in Vietnam as McCain did, “We would take that case, and we would win that case.”

Rudy Morris, who was two months shy of his 60th birthday when he died from glioblastoma, joined the Army at the age of 17, went to Vietnam at 18, and “came home a different person at 19,” said his widow, Margee Morris.

From July 1970 to July 1971, Margee said, Rudy was a tanker in Vietnam whose letters home talked all about Agent Orange and other toxic spraying and how it rained down on him.

“He talked about bathing in the water that had been sprayed,” said Margee, who developed the Facebook page, “Vietnam Veterans with Glioblastoma Multiforme Stage 4 Brain Cancer.”

There’s a public page, as well as a private page with 470 members, mostly widows whose husbands served in Vietnam and were diagnosed with GBM.

When she sent her husband’s first disability claim, Margee said, “I sent the VA a picture of him bathing in the dirty water in Nam when they were out on patrol. Nothing has convinced the VA of the connection between being sprayed with dioxins and glioblastoma many years later.”

Despite the growing consensus in the American medical community that GBM can be caused by Agent Orange, Vietnam War veterans with this type of cancer and their families have found it difficult get their disability benefits from the VA.

A much smaller, but significant number has gotten disability cases approved. But the rest just keep fighting. And hoping.

And some of these widows, who come from a generation in which many wives stayed home and took care of their families, are now struggling to get by. Many are losing their homes, and worse.

While these widows each expressed their sadness over McCain’s diagnosis in interviews with Healthline, they voiced a common hope that this news will create more awareness of the issue and bring some justice for their husbands who served their country.

They also want to correct some public misconceptions about Agent Orange and GBM.

Kathy Josenhans, whose husband was a Navy veteran like McCain and diagnosed with GBM, died at age 57.

She has become an advocate for her fellow widows and a moderator of the Facebook group. She doesn’t like it when she sees misinformation in the media — be it from a liberal, moderate, or conservative.

She said she was upset when she saw a commentary about McCain last week by Fox News contributor Dr. Marc Siegel.

“Could his [McCain’s] experience in Vietnam have increased his cancer risk?” Siegel asked, then stated, “Most studies have not demonstrated a link between Vietnam service and exposure to the herbicide used by the U.S. military in battle, Agent Orange.”

This comment didn’t sit well with Josenhans, who in a letter to Seigel, wrote:

With deepest respect Dr. Siegel, there is a known connection between this deadly brain cancer and Vietnam-era Veterans. There are many opinions by professors who have already linked this deadly tumor to dioxin and PCBs also can mimic dioxin.

“I watched your segment today and struggled emailing you. I am a widow of a Navy diver (6 years Vietnam era) … I’ve got his medical records and I’m on my 6th appeal with the VA, still fighting for his benefits. Many widows have already won their claim for 100% service connection. Just thought you’d like to know. Regards, A fighting widow.”

Everyone interviewed for this story expressed sadness and condolences to McCain and his family, and no one questioned McCain’s bravery or his service to his country.

However, many said McCain could have done a lot more over the years for veterans and their families.

And there is some unambiguous resentment among veterans that McCain refused to be treated for his cancer at the Phoenix VA and instead chose the Mayo Clinic.

The Mayo Clinic is a hospital that has been removed from the VA’s Veterans Choice Program, which was created to provide healthcare closer to home for veterans.

McCain, many sources say, always urges his voters to seek care at the Phoenix VA.

“We’ve all written letters to Sen. McCain thinking he would be the most passionate person on this mission,” Josenhans said. “What has happened to Sen. McCain is a tragedy for him and his family, but it’s also an opportunity for him to do right by his fellow Vietnam veterans with glioblastoma and their families. He has an opportunity to make this right.”

Morris said she has also contacted McCain several times for help and has never gotten even a courtesy reply.

“I emailed him on his website. I got no response from him at all,” she said. “It’s sad with him being a Vietnam vet that he couldn’t help us.”

Morris told McCain that while a few families dealing with GBM had won their claims, “most families have been denied.”

She also told McCain that widows were losing their homes and vehicles after the deaths of their husbands.

“I told him we had all the documentation to back us, too,” she said. “So now he is going through what all of us went through, and I wonder if he is thinking if serving in Nam caused his glioblastoma.”

In a statement last week after the news broke about McCain’s diagnosis, John Rowan, national president of Vietnam Veterans of America, called McCain a fighter who “endured brutal treatment as a prisoner of war in Vietnam, and we know he’ll be a fighter now in his battle against brain cancer.”

Rowan went on to say that McCain’s “fighting spirit will serve him well now, as it did 45 years ago in the Hanoi Hilton and other hellholes.”

Rowan added, “We are saddened to learn that yet another Vietnam veteran has been diagnosed with aggressive brain cancer. Vietnam veterans are all too familiar with glioblastoma, which seems to visit our brothers and sisters at a far greater rate than our non-veteran peers.”

For years, Rowan said, “We have suspected that our exposures during our military service have caused this cancer cluster. Unfortunately, brain cancer is not on the presumptive list for exposure to Agent Orange, despite the efforts of our fellow veterans and their family members.”

Thomas Bandzul, a veteran and veterans’ advocate, who is legislative counsel for Veterans and Military Families for Progress, and past associate counsel for Veterans for Common Sense, said McCain has not supported his fellow veterans as much as he should have.

“Many veterans have told me about their pleas to McCain to help with their claims,” Bandzul said. “As far as I know, he did little more than have a staffer write a letter to the VA, but he never endorsed a cause for a veteran to either get increases in benefits or allowances, with one exception being a uniform allowance for retired military.”

Bandzul added, “I do not know of a single instance wherein he tried to help a veteran with anything, but I have been conversant with veterans who were turned away from his office and received no help at all.”

McCain’s voting record on veterans issues while in the Senate has been a mixed bag.

His “McCain Bill” enacted in 1991, which required the secretary of defense to publicize information about men and women who were unaccounted for from the Vietnam War, got widespread support.

McCain was also co-sponsor of the 2014 VA overhaul that proceeded the veteran wait times scandal at the Phoenix VA.

But in 2008, McCain asserted he was in support of the GI Bill for the 21st Century — which was also supported by every major American veterans’ service organization — and then did not show up to a vote on it.

McCain even introduced a competing GI Bill that reportedly would have left the average veteran with $20,000 in student loan debt.

According to a variety of sources including GovtrackUS, Library of Congress, VoteSmart, and McCain for President, from 1993 to today McCain has voted against veterans bills 14 times while voting for veterans bills 11 times.

In 2006 alone, McCain voted against providing $20 million to the VA for healthcare facilities, and voted against providing $430 million for VA outpatient care.

But in 2005, McCain voted for funding veterans’ benefits, and voted to provide providing emergency funding for veterans’ services.

In a Senate Armed Services Committee in 2016, McCain reportedly defended the University of Phoenix, the for-profit school that was widely criticized for its predatory practices against veterans.

McCain blasted the Pentagon and the Center for Investigative Reporting for going after the school, one of McCain’s biggest campaign donors.

But in a subsequent investigation, the Department of Defense confirmed the Center for Investigative Reporting’s story and barred the University of Phoenix for three months from all U.S. military bases worldwide.

Steve House, who joined the U.S. military just after the Vietnam War, was ordered to bury multiple barrels of Agent Orange at the Camp Carroll Army base in South Korea.

The exposure lead to multiple serious illnesses.

House fought for a decade with the VA to get his disability, traversing the country collecting evidence confirming what he was saying actually happened.

House sent eight registered letters to McCain. But got no replies.

He was finally awarded his disability benefits in 2014.

“I was saddened to hear about Sen. McCain’s diagnosis. He has a rough fight ahead of him,” said House, who hopes McCain’s illness makes the toxic exposures to U.S. troops a front-burner issue.

“John was the first politician I reached out to for help when I tried to prove there was a cover-up going on between the Department of Defense and the Department of Veterans Affairs,” House said.

“He knew all about the illegal burial of Agent Orange that took place at Camp Carroll two years before I ever went to the press,” House added.

House said Americans need to know that Agent Orange is “one of the most insidious compounds ever created by man. Its effects on our health and on our environment will not go away for thousands of years. It continues to kill. I will say a prayer for John.”