Scientists have figured out how to brew heroin’s raw ingredient in genetically modified yeast, raising concerns over whether the process should be regulated, according to The New York Times.

Until now, heroin production has required opium poppies, which yields morphine. Scientists at two California universities published a paper this week in Nature Chemical Biology that explains a crucial step in turning genetically modified sugar-fed yeast into morphine.

In a commentary on the study, Kenneth A. Oye, a professor of engineering and political science at M.I.T., says the bioengineered yeast strains should be locked up in secure labs, and access to the yeast’s DNA should be restricted to prevent drug cartels from getting their hands on it.

“By providing a simpler — and more manipulable — means of producing opiates, the yeast research could ultimately lead to cheaper, less addictive, safer and more-effective analgesics,” Oye wrote. “And in generating a drug source that is self-replicating and easy to grow, conceal and distribute, the work could also transform the illicit opiate marketplace to decentralized, localized production. In so doing, it could dramatically increase people’s access to opiates.”

Oye warns that because yeast is easy to conceal, grow and transport, drug cartels and law enforcement agencies would have trouble controlling the distribution of an opiate-producing yeast strain. “All told, decentralized and localized production would almost certainly reduce the cost and increase the availability of illegal opiates — substantially worsening a worldwide problem,” Oye notes.

A spokesman for the Drug Enforcement Administration (DEA) told the newspaper his agency “does not perceive an imminent threat” because no modified yeast strain is commonly available yet. If that happens, he said, DEA labs would be able to identify heroin made from it.