(CNN) A rise in the use of medical marijuana has spurred a debate about organ transplantation, and it's changing some laws across the nation.

Garry Godfrey found out in 2010 that he was removed from an organ transplant waiting list in Maine due to a health risk associated with his use of medical marijuana, CNN affiliate WGME reported . Now Godfrey is speaking out in support of a bill in Maine that would prohibit hospitals from determining a patient's suitability for transplantation solely on the basis of medical marijuana use (PDF).

That bill is in committee, and similar legislation has been passed in other states, including California Delaware and New Hampshire (PDF).

Godfrey, 32, uses marijuana to relieve pain and other symptoms he suffers due to Alport syndrome , a genetic condition that can cause renal failure -- and he needs a new kidney, WGME reported.

"I've tried so many pharmaceuticals and none of them worked, but the medical cannabis does," Godfrey told WGME. "It helps me function. It helps me take care of my kids."

But if a transplant candidate already has a compromised immune system and is taking prescribed or recreational marijuana, that can increase their risk of a deadly fungal infection known as Aspergillosis during the transplantation process, according to a press statement released this week by the Maine Transplant Program. Once off marijuana, patients can be put back on the waiting list.

Meanwhile, researchers are desperately trying to better understand the potential health risk that may be associated with marijuana use and organ transplantation.

'When we turn someone down, it's a personal failure'

"The thing that comes up with marijuana is the risk of pulmonary infections, (specifically) fungal infections with Aspergillosis," said Dr. David Klassen, chief medical officer at the United Network for Organ Sharing

Such infections "can be an absolutely devastating complication but, you know, how often does that really happen? How likely is it? Those questions are less well understood," Klassen said. "It's a question of how much risk does that really impose versus the benefit that the patient potentially gets from getting the transplant."

The Maine Transplant Program has a policy in place around marijuana because two people who had transplants died as a result of the fungal infection, Maine Medical Center spokesman Clay Holtzman said. Both patients had smoked marijuana, which suggests it might have been the cause of the infections. It's not clear what the risks are around edible medical marijuana, he said.

The issue is an emerging puzzle that is also shaping conversations within the transplant community, said Dr. James Whiting, surgical director of the Maine Transplant Program at Maine Medical Hospital.

"These conversations around medical marijuana will continue, and I think that we will try to find ways, whether they be using edibles or other things, to allow people to be listed and transplanted," Whiting said.

"The transplant community is always going to be focused on using as many organs as possible," he said. "Our goal is to transplant as many Mainers successfully as we can. That's how our program's evaluated. That's how I'm evaluated. That's why we're here. So when we turn someone down, it's a personal failure in many ways."

More than 118,000 people in the United States are waiting for a life-saving organ transplant, according to UNOS.

The behind-the-scenes politics of organ donation

The policies of most transplant programs, which determine who gets on a waiting list, are evaluated through UNOS and the Centers for Medicare and Medicaid Services , among other agencies.

"The decisions for a center to accept anything -- (for example) some people say I'm not going to transplant anybody over the age 50 or 60 -- they're allowed to do that," said Dr. John Fung, chief of transplantation surgery and director of the Transplantation Institute at the University of Chicago Medicine.

Other than protecting against racial or gender discrimination "no rule says you have to transplant any given population," Fung said. "But each center basically evolves their own criteria," he said.

"The people who review our transplant programs, Medicare and UNOS, review us on a periodic basis to make sure we have those criterion and that they're not discriminatory and that we are adhering to them," Whiting said about the individual policies of transplant programs.

"That being said, there is a lot of local variability allowed in those inclusion and exclusion criteria," he said. "So across the country, someone who gets turned down in one program may actually be able to go to another program."

Some variability was seen among how heart and lung transplant providers listed medical marijuana patients in a paper that published last year in the journal Circulation: Heart Failure

For the paper, 360 heart and lung transplant providers from 26 countries around the world completed online surveys about their individual practice patterns and attitudes. About 64% indicated that they supported listing transplant recipients who legally use medical marijuana and about 27% supported listing patients who legally use recreational marijuana.

'People feel like they're in a Catch-22'

"The decision on whether to list the patient or not is really up to the transplant program. We don't have any real policy that says a patient like this must be accepted or must be denied," said UNOS's Klassen.

Yet, "there are some things that are quite common to all transplant programs," he said. "A patient that has active malignancy cancer , (for example), typically those patients are not for transplant."

Current or recent cancer diagnoses are among the few widely accepted medical conditions that might rule out organ transplantation , according to UNOS. Morbid obesity, for instance, is also among those common conditions.

Certain long-term medications, including prescribed marijuana, can also impact organ transplantation eligibility, such as, "people who might be on an anticoagulant because they needed a heart stent," said Maine Medical Hospital's Whiting.

In some cases, "the only reason they knew they needed a heart stent was because they went through the testing for transplant and now they can't get the transplant because they're on an anticoagulant ," he said. "A lot of these people feel like they're in a Catch-22."

Parallels of HIV then, medical marijuana now

Human immunodeficiency virus, or HIV, used to be widely seen as a condition to disqualify a patient for organ transplantation, Whiting said. But then, opinions changed.

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"One of the absolute contra indications to receiving an organ was HIV positivity. One of the absolute contra indications to giving an organ was HIV. And, of course, we know now that's not true at all," Whiting said.

"Certainly I think most people now, if not everybody, realize that HIV patients can do quite well after transplant, but," he said, "that change happened over 10 to 15 years."

When research studies started revealing that the anti-viral therapy for HIV could prolong survival, that shifted conversations about organ transplantation, said the University of Chicago Medicine's Fung.

"Around 1997 I had to argue to all of my colleagues that, 'Hey we shouldn't just say that transplants with HIV are out entirely. Look at all this new literature and technology that's coming out. Let's think about it,'" Fung said. "So, I would like to think that we were, as a community of transplanters, reasonable and willing to accept new findings and data as we evolve our criteria."

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Fung sees many parallels between past conversations about HIV and organ transplantation and current conversations about medical marijuana and organ transplantation, he said.

"The biggest question, in this day and age of increasing acceptance of medical marijuana and its benefits, is: Should it be considered illegal or as a factor in deciding whether or not somebody's a candidate for transplant or not?" Fung said about medical marijuana.

He mentioned that he knew a young man who was a medical marijuana patient in Ohio. That patient was turned down for organ transplantation "and he died," Fung said.

"My views have gone more towards allowance of a patient with medical marijuana, documented for a good medical reason, to be allowed to take it without getting penalized for it," Fung said. "I would still say that that is the minority view."

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In the future, UNOS's Klassen said that he thinks more transplant programs will continue to evaluate and evolve their policies to address the changing climate around medical marijuana.

"There is an increasing acceptance of medical marijuana as an acceptable and relatively commonly prescribed medication," Klassen said. "I think programs are incorporating that into their assessment of patients."