Researchers at the Minneapolis Veterans Medical Center believe they are closer to connecting the dots between soldiers' exposures to burn pits and toxic fumes and the broad array of health problems that can follow.

Using a new animal model, rodents are placed in an enclosed chamber and move freely while they inhale substances that simulate what soldiers experienced during deployments to Iraq or other locations in Asia or Africa. Carbon particles, for example, represent the black smoke soldiers inhaled when everything from tires to equipment to ordinance was burned near their bases.

The goal is to identify patterns of inflammation, produced by the immune system in response to the toxins, that signify burn pit-related illnesses and predict the resulting health problems, said Tammy Butterick, a VA health science specialist leading the research.

"Different types of inflammatory responses … can be identified by profiling biomarkers in various tissues such as blood," she said. "There's markers that would indicate cancer, heart or airway disease. Those markers do overlap but can also indicate the onset of specific diseases."

Results of the carbon exposure experiment were presented at the Minneapolis VA earlier this spring and are due for publication in a medical journal this summer. Next steps include different combinations and concentrations of inhaled substances that simulate the toxic exposures from burn pits.

"Ultimately that's the goal, to test and identify diagnostic markers," Butterick said.

The VA research comes amid heightened recognition and legislative support for veterans with burn pit-related illnesses. An estimated 3.5 million veterans were exposed to burn pits and related airborne contaminants, but many who believe their health problems are related have struggled to prove it and qualify for service-connected medical and disability benefits.

Sen. Amy Klobuchar, D-Minn., helped push legislation through the Senate last month that would automatically presume a service connection for veterans with certain lung or other disorders who served in areas where burn pits were used. Action on the bill, which also would increase training on treatment of these illnesses, has been delayed in the House amid cost and procedural concerns.

"When we ask our young men and women to defend our nation, we make a promise to be there for them when they return home," Klobuchar said. "I've long led efforts to ensure servicemembers and veterans exposed to toxic substances, including burn pits, receive the health care and benefits they deserve."

Lacking a presumption, Julie Tomaska of Woodbury said it took her three years and the expense of an attorney to access veterans benefits by having her lung disease connected to her burn pit exposures during her two tours in Iraq with the Minnesota Air National Guard.

The condition is like "having a big rubber band on your chest," she said. "Mornings are brutal to be honest. It's just rough getting up."

Tomaska, 44, also lacked the kind of simple diagnostic test the VA research is hoping to inspire. Instead, she needed an open-lung biopsy to identify the rare and hard-to-detect scarring in her lungs, and post-operative recovery took a year.

"It was really, really big for me to have that diagnosis and know, like, I'm not crazy," she said. "But it took a toll."

Tomaska has become an advocate, serving as a scientific adviser to the Burn Pits 360 national group and co-founding the the Amie Muller Foundation, named after a Minnesota veteran who died at 36 from pancreatic cancer. Diagnostic markers of an elevated cancer risk because of exposures might have been lifesaving, Tomaska said.

"They didn't run all the tests that they would normally, because she wasn't a 60-year-old man," she said. "So, they missed it. And by the time they caught it, she was stage 4."

Tomaska was a Minneapolis VA researcher for a decade, and she talked about her health problems with Butterick, her colleague and friend.

Butterick grew motivated to tackle the subject. Her research team quickly grew to include experts in inhalation toxicology at the West Virginia University School of Medicine as well as engineers and specialists in cancer and other diseases linked to toxic inhalations.

"At first it seemed very simple, but it turned out it's a complicated thing to do to model inhalation exposures," she said.

A whole body inhalation chamber was the solution, creating a more realistic scenario of inhalation during prolonged, everyday activities — albeit in rodents and as a proxy for human exposure.

"You're never going to be able to repeat what someone has been exposed to, especially when they're out in a military base doing whatever they were assigned to do," she said. "But we can provide a surrogate for that."

The research builds on existing respiratory research, including some exploring the consequences for first-responders and others following the collapse of the World Trade Center towers in New York in 2001.

Researchers at Stony Brook University in New York used their geological expertise to find harmful metals in lung tissue that otherwise weren't being detected by common X-rays and exams. They used soil samples from an Iraq military base and found that inhalation in mice deposited sharp, asbestos-like metals — probably titanium — in their lungs.