Policymakers trying to figure out how to oversee a new generation of genetically engineered crops face a dilemma: gene-editing techniques are making it more difficult to tell what a GMO even is.

That’s important because the way GMOs are defined in new regulations, or in rules like the one in Vermont that will require food companies to label products containing ingredients “produced with genetic engineering,” could restrict or open opportunities for innovation in agricultural biotechnology.

Of course, the term “GMO” is colloquial, not scientific. It stands for “genetically modified organism,” but we don’t call all crops whose genes have been modified GMOs. We’ve reserved the label specifically for plants or animals containing DNA from another organism. That works for most of the genetically engineered crops in commercial production, which contain genes from bacteria that make them resistant to insect pests or certain herbicides. But techniques like CRISPR, which can be used to make precise modifications to a plant’s DNA without adding any new genetic material, are calling the term’s usefulness into question, at least from a regulatory standpoint.

Gene editing has already given rise to beneficial new traits through the removal of just a small number of DNA letters. A new potato doesn’t produce as much acrylamide, a suspected carcinogen, when it is fried. A mushroom, the first CRISPR-made crop to achieve the official green light from the U.S. Department of Agriculture, doesn’t brown as easily.

A gene-edited version of white button mushrooms like these is unregulated by the USDA.

Are these crops GMOs? That depends on whom you ask. Most opponents of genetic engineering in agriculture would say yes. Federal regulators in the U.S. effectively say no, at least for the time being.

Under the current system, the USDA is the main regulator of genetically engineered crops, and the agency’s authority stems from a law that puts it in charge of protecting crops and the environment from “plant pests.” Most of the previous generation of GMOs triggered regulation because they were made using soil bacteria to deliver new genetic material, because the new gene itself came from bacteria, or both. But a growing number of new crop varieties are avoiding regulation because the techniques used to make them do not require the use of a plant pest, and the plants don’t contain DNA from one.

Varieties that have been modified without adding new DNA are blurring the distinction between genetic engineering and conventional breeding. The changes to their genomes are similar in type to those achieved through a common technique called mutagenesis, which entails using chemicals or radiation to induce mutations, or genetic changes, that generate beneficial new traits. Mutagenesis is considered a conventional breeding approach, and it has been used to develop thousands of new varieties over the past several decades, including the Ruby Red grapefruit.

If the nonbrowning mushroom made using CRISPR is a GMO, why isn’t a crop developed via mutagenesis one? “It would be reasonable to think about a GMO as anything where a genome has been manipulated in the laboratory,” says Richard Amasino, a professor of biochemistry at the University of Wisconsin, Madison. “If you are mutagenizing it with a chemical, you’ve manipulated the genome in a laboratory.” Either way, a change of just a few DNA letters is similar to changes that happen spontaneously in nature, he says.

The term “GMO” doesn’t work anymore, says Dominique Brossard, a professor of life science communication, also at the University of Wisconsin, Madison. Gene editing is “completely revolutionizing what we think genetic engineering might be,” she says.

The bottom line is that calling something “genetically engineered” says nothing in itself about the risks to human health or the environment that it may present. That’s why a committee of 20 experts, including Amasino and Brossard, recommended in a comprehensive report published last week by the National Academy of Sciences that new regulations focus not on the process used to make a new plant variety but, instead, on the plant’s new characteristics. That would be more like the system used in Canada, where what matters to regulators is not the breeding technique used but whether the plant is “novel.”

The committee also argued that technologies for analyzing a plant’s DNA, as well as the molecules and proteins produced in its cells, can be used to test new varieties for unintended changes and determine whether the crops pose new risks compared with their nonengineered counterparts.

Those conclusions will now be taken under consideration by the USDA, which earlier this year informed the public that it would explore rule changes. Current regulations define “genetically engineered organism” to mean one “genetically modified by recombinant DNA techniques,” which excludes things like the CRISPR-made nonbrowning mushroom.

The agency is considering several new definitions for use in the new rules, which don’t include one for “genetically engineered.” The most important one defines “biotechnology” in terms of techniques for deleting segments of the genome, adding segments to it, or changing it by “directed altering.” Under the proposed definitions, a regulated organism would be one made with biotechnology that poses a plant pest or noxious weed risk.

Meanwhile, Vermont’s labeling law, which goes into effect in July, has prompted several major food companies to use the “produced with genetic engineering” label nationwide. Does the law cover gene editing? “The short answer is yes,” says Todd Daloz, a Vermont assistant attorney general. But he says a scenario in which gene editing is used to produce a result similar to one achievable through conventional breeding “merits further consideration.”