Another option, the precautionary principle, while potentially flexible, functions in a context of “what if” instead of evidence, rendering it toothless and inconsistent. The Obama administration recently applied this principle in its unprecedented override of FDA approval of over-the-counter sales of Plan B, the “morning after” pill, asserting that drug makers couldn’t “conclusively establish” its safety for 11-year-old girls. This conclusion illustrates a main fault of the principle: It doesn’t balance uncertainty against known risks, which are substantial for 11-year-olds who become pregnant.
Frameworks aside, pending further evaluation, these new findings suggest that humans and other animals have lived with ingested plant miRNAs for a long time. No evidence exists of altered miRNAs in genetically modified plants, so the GM plants that are now on the market won't affect that longstanding relationship.
In trying to link miRNAs and GM foods, LeVaux seems to confuse this type of small RNA with another kind that also regulates protein production in our cells. Some GM plants have been engineered to produce “small interfering RNA,” or siRNA. In the short-lived 1994 GM product the Flavr Savr tomato, for example, engineered siRNAs specifically blocked production of a protein that normally hastens tomato ripening.
LeVaux seeks to emphasize the dangers of one with examples of the other. Some plants have been engineered to create siRNAs or longer RNAs that silence toxin-processing genes in insect consumers. But these are perfectly matched to their insect targets, and no studies have identified any such GM plant molecules in human tissues. Further, siRNAs and miRNAs are not simply interchangeable. They can have similar effects, but cells process and use them differently.
Some groups—with no industry affiliation, thus far—do research artificial miRNA technology to alter plant characteristics, although its use in crop plants remains speculative. If artificial miRNA GM foods become possible, would the Zhang data “blast a hole” in substantial equivalence? No. Substantial equivalence would dictate further testing.
Speaking of testing, LeVaux asks, “A tomato with fish genes? … That, to me, is a new plant and it should be tested. We shouldn’t have to figure out if it’s poisonous or allergenic the old fashioned way, especially in light of how new-fangled the science is.” (Next, he’ll be yelling at scientists to get off of his lawn.) But substantial equivalence doesn’t mean “untested.” Researchers did develop a tomato that contained an inserted Arctic flounder gene to render the plant cold tolerant. But the tomato foundered in tests of its cold tolerance. Had it not failed, according to one expert review, “additional environmental and safety tests would have been conducted” to demonstrate substantial equivalence—as was done for the Flavr Savr tomato. As that review notes, all current GM products in the U.S. marketplace have undergone a full regulatory review.
Such tests aren’t full-scale clinical trials on human volunteers, but they do assess how toxic or allergenic GM foods might be in ways that are similar to nonclinical safety assessments for pharmaceuticals. In addition, thanks to technological advances in the “–omics” fields that allow comparisons of genomes, proteins, and metabolites between organisms, these tests can now incorporate comparisons of the molecular profiles of GM and non-GM versions to identify any distinctive differences that might warrant further investigation.
Largely overlooked in all of the GM alarmism are the real implications of the Zhang miRNA study. Human versions of these tiny molecules play many roles in development and disease, and now it seems that some plant miRNAs can survive our digestion and enter our bloodstream. What influence, if any, do they have on our health? That’s the question that shouldn't get lost amidst the shrapnel of LeVaux's social-media bombshell.
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