No "substantiated" evidence exists that genetically engineered crops have caused health problems in humans or damaged the environment, but it’s too soon to be making broad statements, positive or negative, about laboratory-based manipulations of crop genomes, an elite panel of scientists concluded in a report Tuesday.

The panel of 20 experts, most of them academics, was convened by the National Academies of Sciences, Engineering and Medicine and asked to review various claims about the benefits and hazards of GE crops. The 388-page report is nuanced and, on some issues, equivocal, with comments from all sides of the issue.

Despite the heavyweight credentials of the panelists, their assessment seems unlikely to quiet the polarized debate over crops that supporters say can feed a hungry world but which critics have referred to as “Frankenfood.”

“We make a very strong point that sweeping generalizations about GE crops are misguided,” said committee head Fred Gould, a North Carolina State University professor.

The biotech industry has long argued that GE crops are safe to humans, animals and the environment generally and that these crops can improve yields and in some cases reduce the need for pesticides. Previous studies from the National Academies have generally backed the industry position; the prevailing scientific view is that there is nothing intrinsically more dangerous about changing a genetic trait through a laboratory technique than through the kind of field-based plant breeding that farmers have employed for millennia. Already, much of the corn and soybeans grown in the United States is genetically modified.

The new report essentially reiterates that view, saying government regulators shouldn’t focus on the process by which a plant is altered but rather on the plant itself and whatever traits it has. Every newly introduced plant should undergo safety testing regardless of how it was created, the report states. But, it also says, the fact that previous GE crops have not caused health or environmental problems does not mean that all prospective GE plants should be presumed to be benign.

That point is particularly important, the researchers said, given rapidly evolving laboratory processes. New techniques include CRISPR, the revolutionary gene-editing tool that lets researchers delete or inactivate genes without introducing  genetic material from other organisms.

“One of the take-home messages is, it makes less and less sense to talk about genetic engineering as a distinct category of plant breeding,” said Michael Rodemeyer, an attorney and former University of Virginia professor who served on the committee. “What we’re seeing is rapid development of technology blurring all of those lines.”

But the recommendation of a process-agnostic approach to new crops -- one that would wouldn't single out laboratory-engineered plants from ones bred traditionally -- drew immediate criticism from the technology watchdog organization ETC Group.

“In our view the report is inconsistent on the crucially important question of whether or not to regulate the new techniques such as genome editing and synthetic biology. That is the most urgent question regulators face right now, and this report doesn’t  come to logical conclusions,” ETC spokesman Jim Thomas said by email. The potential for gene-editing techniques to have “off-target” effects should persuade regulatory agencies to focus on the process and not just the ultimate product, he said.

Thomas noted that the general public already is highly suspicious of genetically engineered food. "The consumer is saying, 'We don’t trust this stuff and we don’t trust the companies that are pushing it,'" he said.

Dana Perls, senior campaigner on food and technology with Friends of the Earth, said the biotech industry has long supported the National Academies.

“I’m concerned that their findings and recommendations are deceptive and even biased toward industry interests," she said in advance of reading the report.

The National Academies did not appoint anyone from the biotech industry to the committee, nor use any money from the industry to fund the study, a spokesman said, adding that all committee members were required to disclose any potential conflicts of interest.

The panelists knew they were entering contested territory that is influenced not just by scientific data but also by concerns about corporate agriculture, the ownership of GE seed supplies and the struggles of small farmers around the world. The debate has social and economic elements that can’t be solved by science alone, according to the report. On the issue of whether the government should require that products sold at grocery stores be labeled if they contain genetically modified organisms, for example, the panel declined to take a firm position. It instead detailed pro and con arguments.

Michael Hansen, a senior scientist with Consumers Union, praised that element of the report: "When it comes to GMO labels, the NAS report points out that there are value choices that consumers want to make when they shop for food. We're pleased to see that the report cites the wealth of polling data showing consumers want GMO labeling."

In an email to The Post, Hansen pointed out that the committee acknowledged that genetic engineering could introduce  allergens into a plant that would be hard to detect in tests prior to the food hitting the open market. That's another reason for labeling, Hansen said.

The new report stressed that very few GE crops are currently in heavy cultivation. Only two types of laboratory-derived genetic enhancements have been widely used so far – one that confers tolerance to herbicides, and another that reduces vulnerability to insect pests.  Badly managed GE  crops can lead to herbicide resistance in weeds and pesticide resistance among insects.

“We wanted to be transparent, we wanted to be inclusive, we wanted to include all the voices that have expressed concern about this technology or have expressed support," said Dominique Brossard, a University of Wisconsin professor who studies risk communication in emerging technologies.

“We have heard all the sides of the argument," she said. "Potentially, we may displease both sides of the issue that is extremely polarized.”

Once humans started cultivating wild plants, fruits and vegetables got a lot more colorful. (Daron Taylor, Dani Johnson, Osman Malik/The Washington Post)

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