When it released a 408-page report on genetically engineered (GE) crops yesterday, the National Academies of Sciences (NAS) said claims about GE crops—both pro and con—“have created a confusing landscape for the public and policy-makers.” But the report itself might not clear up all the confusion.

While the NAS report says there is no conclusive evidence to suggest GE crops now on the market have any more “risks to human health” than conventional crops, it also stresses the need to avoid sweeping generalizations about these crops, which it says must be evaluated on a case-by-case basis. It also says there is no “conclusive cause-and-effect evidence of environmental problems from the GE crops,” while detailing a great deal of information that the Academy deems cause for concern.

For example, the NAS report found that so many weeds have become resistant to herbicides in places where crops engineered to be herbicide-tolerant are grown that it is now a “major agricultural problem.” In addition, the Academy says more up-to-date methods of assessing GE crop safety are needed and that “regulators should focus on the extent to which novel characteristics of a plant variety (both intended and unintended) that are likely to pose a risk to human health and the environment.”

The report also calls for greater authority for federal agencies so they can better monitor and deal with environmental impacts that may occur after GE crops are approved and in use. And in a number of ways it kicks the can down the road, leaving many important questions of impact and safety unanswered. Among these are questions about environmental impacts of herbicide use associated with GE crops.

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Whether the report—written by a 20-member committee that reviewed more than 1,000 research and other publications on GE crops—will clarify the issues or quell the vociferous public debate on this issue remains to be seen. But at first look, it seems unlikely to because both the agricultural and biotechnology industry and environmental advocates appear to be hailing the points that reinforce their positions.

Should Weed-Resistance be Considered an Environmental Impact?

The bulk of the GE crops on the market have been modified to resist herbicides and insects. But that technology appears to have backfired. The NAS report notes that “both for insect pests and weeds, there is evidence that some species have increased in abundance as IR [insect-resistant] and HR [herbicide-resistant] crops have become widely planted.” NAS suggests that rather than relying solely on pesticides, farms should use more integrated—that is more varied—forms of pest and weed control to forestall further spread of chemical-resistant insects and weeds, a recommendation supported by both the agricultural chemical industry and environmental advocates.

“One of the major take-home messages of the report is that herbicide-resistant GE crops have contributed significantly to the evolution of weed resistance,” Natural Resources Defense Council (NRDC) senior scientist Sylvia Fallon told Civil Eats. “That is consistent with our concerns about the next generation of herbicide-tolerant crops. The report is showing that continuous use of herbicides is not a way to address weed resistance.” Fallon pointed to the latest GE crops to be approved, which have been engineered to tolerate a pesticide combination known as Enlist Duo, developed to help farmers deal with weeds that had become glyphosate-resistant.

When it comes to questions of impacts associated with this herbicide use, NAS says, “better and more transparent data on actual herbicide use is needed” before those effects can be evaluated. “More pounds [of herbicide] per acre doesn’t automatically translate to more harm to human health or the environment,” said NAS committee chair Fred Gould, professor of entomology at North Carolina State at the press briefing.

At the briefing, NAS committee members pointed to a chart of pesticide use that showed herbicide use for the three major U.S. GE crops—corn, cotton, and soybeans—in kilograms per hectare* with no remarkable changes in use between 1995 and 2010. But overall acreage has increased dramatically. And in looking at overall volume for the same time period, the U.S. Geological Survey shows glyphosate use for these crops increasing from about 1 million pounds to over 200 million pounds.

“Glyphosate use has gone up tremendously but other [herbicides] have gone down, so overall pounds per acre have not changed so dramatically,” Center for Science in the Public Interest (CSPI) biotechnology project director Gregory Jaffe explained to Civil Eats. Yet given the persistent concerns about health effects of glyphosate, that still leaves many questions unanswered. And the report doesn’t answer these questions, but instead says, “the complex nature of assessing long-term environmental changes often made it difficult to reach definitive conclusions.”

For these reasons and others, CSPI’s Jaffe said, “it is disappointing that the report does not recommend that the [U.S. Food and Drug Administration]’s oversight change from a voluntary to a mandatory process.”

Monsanto, a major manufacturer of glyphosate, told Civil Eats in a statement, “After 30 years of research and assessments, the science and safety behind GE crops has been well established and strongly supported by the scientific community—and today’s announcement by the National Academies underscores this conclusion.” CropLife America and Bayer CropScience did not yet have comments to offer.

Calls for Transparency and Better Regulation

While saying that there is no conclusive cause-and-effect evidence of environmental problems associated with GE crops, the report makes precautionary recommendations for additional oversight by federal regulators involved with GE approval: “Regulatory agencies responsible for environmental risk should have the authority to impose continuing requirements and require environmental monitoring for unexpected events after a GE crop has been approved for commercial release.”

It’s notable, said Scott Faber, Environmental Working Group vice president of governmental affairs, that while the report “didn’t find evidence that GMOs that have been commercialized are unsafe to eat, it did see the potential for future risk and urges policy-makers to modernize the regulatory system and do more-post marketing monitoring.”

The NAS report also calls attention to the fact that “new technologies in genetic engineering and conventional breeding are blurring the once clear distinctions between these two crop-improvement approaches.” Take CRISPR gene editing, which does not combine genes from more than one species and which the USDA has expressed a lack of interest in regulating. For these reasons, the NAS report says assessing each GE crop individually will be “critical to detecting unintended changes in new crop varieties.”

On the hot-button issue of GMO labeling, the report takes a similar approach. While it says it found no human health reasons to justify mandatory labeling of food produced with GE crops, NAS said questions about labeling involve “social and economic choices that go beyond technical assessments of health or environmental safety,” considerations that include “consumer autonomy.”

Throughout the report, NAS calls for greater transparency, particularly in informing the public about GE crop development and regulation. Regulatory authorities, it says, should be “proactive in communicating information to the public” and in seeking public input on these issues given that GE crops raise social and cultural, as well as scientific and legal questions.

“The report confirms the importance of transparency and the need for mandatory GMO labeling on the package,” said Gary Hirshberg, chairman of Stonyfield Farm and the Just Label It campaign. He added that it also “confirms that the GMO regulatory system is broken” and that glyphosate use is rising.

“Consumers want the right to know how their food is produced so they can decide for themselves whether the current regulatory system is adequate or whether rising glyphosate use is safe,” said Hirshberg.