New treatments that target cancer with radioactive drugs are raising questions about whether they create a health risk for workers who cremate the bodies when the patients die.

In February, doctors at the Mayo Clinic in Arizona published findings in an influential journal of low-level radiation contamination at a crematory that handled the remains of a patient who received one of the new “radiopharmaceutical” treatments.

One month after the cremation, testing revealed traces of radiation in the crematory oven, vacuum filter and bone crusher.

“Certainly, in our case, the dose to the crematory operator was very low. And because the dose was low, the risk is also very low,” said Kevin Nelson, a radiation physicist at Mayo Clinic in Arizona. “But if that person is continually exposed, what happens with the risk? That’s where I really think we need additional studies.”

In the weeks since the findings appeared in the Journal of the American Medical Association, some safety experts have stressed that current guidelines for wearing gloves, masks and gowns provide good protection from contamination for crematory workers.

The chance of a cumulative risk seems unlikely, they say, since it would require many deaths within one year of treatment landing at a crematory with no notice of medical history.

“The risk of harm to the crematorium operator is so small that it cannot be measured,” said the American Association of Physicists in Medicine in a statement.

Even so, the National Funeral Directors Association said it welcomed further study of the issue. The group noted that crematory operators are supposed to be told whether a body includes pacemakers or radioactive implants.

The Cremation Association of North America said it welcomed more information, as well, while also lamenting what it called “a many-headed hydra of confusion, concern and misinformation” since the Mayo Clinic research was published.

“Let’s take a breath, and learn about what these radiopharmaceuticals are,” said Barbara Kemmis, the cremation group’s executive director. “Often death care, as we refer to ourselves, is reactive to advances in health care.”

About 62 percent of all deaths in Minnesota resulted in cremation during 2017, when the state Health Department says some 27,700 bodies were cremated. State law describes the process as the reduction of a dead human body to “essential elements” by direct exposure to intense heat and flame.

Radiopharmaceuticals join a select group of medical interventions that have raised questions about what safety measures are needed at the crematory.

A statute in Ontario, Canada, prohibits cremation of bodies that have undergone “brachytherapy,” a procedure in which dozens of radioactive “seeds” are implanted near tumors to treat conditions such as prostate cancer. Canadian officials are taking a second look at the statute because the radioactive material fully decays over time and families have increasingly balked at the ban.

Minnesota law says implanted mechanical and radioactive devices must be removed before cremation, but the rule doesn’t apply to radioactive seeds, said Sherrie Flaherty, supervisor in the radiation control program at the Minnesota Department of Health. Instead, the radioactive device rule applies to old heart pacemakers that were powered with plutonium, Flaherty said, and pose an obvious explosion risk.

As a practical matter, the Minnesota law means heart pacemakers are removed, while knee and hip implants are not. Regulators cited one case in the state where a pacemaker exploded inside the crematory chamber, and a ricochet nearly hit the operator.

There’s no state law when it comes to cremation of decedents who’ve received radiopharmaceutical treatments, which doctors say offer some cancer patients new hope for longer and better lives.

In February, doctors at the Mayo Clinic in Arizona published a research letter about a 69-year-old patient who in 2017 was being treated on an outpatient basis with a medicine typically given in eight-week intervals. The day after one such treatment, the man was admitted to a different hospital and subsequently died from his underlying disease.

Caregivers at Mayo learned of the death about a month later. The state conducted tests at the crematorium and found traces of radiation. A test of the operator’s urine didn’t find any evidence of the radiopharmaceutical, but revealed a trace amount of a different radioactive material that’s commonly used in certain diagnostic tests.

The research letter called for studies to evaluate the frequency and scope of radiation contamination in crematories as well as the health implications for workers. It also suggested future safety protocols for “postmortem management” such as evaluating radioactivity before cremation and standardizing notices to crematories.

“With more and more radiopharmaceutical therapy agents coming onto the market, the concern is: Will the risk for the crematory operator become greater?” said Nelson, the Mayo radiation physicist. “Maybe it’s time to see if there should be a federal regulation. There are various state regulations, but there’s not a federal regulation.”

Flaherty, the state Health Department supervisor in the radiation control program, said the Arizona case is raising needed awareness for crematory operators, but she said that radiopharmaceuticals present a very low risk. Patients being treated with the new medicines as well as the radioactive seeds have been released from medical care, Flaherty said, with instructions to keep exposure to others low.

It’s up to family to disclose medical information before cremation, which means some details might not be shared. While that’s “not an ideal situation,” Flaherty said, “it’s not a high-risk situation.”

Some fear attention to the radiopharmaceutical issue will scare patients away from radiation treatments they need.

Radioactive materials are regularly used to help patients, and special precautions aren’t needed when cremating decedents who’ve undergone medical imaging, said Cynthia McCollough, president of the American Association of Physicists in Medicine.

Depending on the treatment type, current guidelines call for surgical removal of radioactive material tissue when death occurs within three months to a year of treatment, McCollough said. After that, the radiation is gone or remains at harmless levels.

Still, some find the current crop of guidelines confusing, said Carey Smith, chief executive at the Bereavement Authority of Ontario. Canadian guidance on radiopharmaceuticals, for example, suggests delaying cremation for weeks or months in some cases, but also says “death-care professionals can rest assured that the radiation risk would still be minimal” if precautions weren’t taken.

As for the Arizona case, Smith said: “I think people are saying: Don’t freak out, yet. Let’s see what the evidence is.”