- RNA interference (RNAi) was also used by JR Simplot of Boise, Idaho to silence PPO production in nonbrowning potatoes, which were approved by the USDA in November (Nat. Biotechnol. 33, 12–13, 2015). For that product, fragments of a single potato PPO gene were re-introduced into potato, activating the RNAi pathway. But unlike the apple, the potato's double-stranded RNA is formed by an inverted repeat transcribed in the tuber and processed into small interfering RNAs that ultimately silence their targets. JR Simplot's crop was also modified to have reduced acrylamide, which was achieved by using RNAi to silence the asparagine synthetase-1 gene (ASn1).
See: How safe does transgenic food need to be? The short: plenty of acute (<= 90 days) toxicity studies as well as details on the nature of the changes and their expected interactions. Not much is studied in the way of chronic toxicity prior to approval.
I would be shocked to find such a change would have anything but chronic toxicity, if any. That's what bothers me most about adding GMO foods to my diet. Chances are, they are going to be fine. But, if they aren't, we will know long after it's too late. It's a luxury, but I avoid them when possible. Organic usually tastes better anyway.
It's not like there aren't studies on chronic toxicity after approval, just not before. It's a contended topic, but to be fair, you don't do any studies on the chronic toxicity of food when you cross a new strain, either, and often that generates much more complex genetic changes. Tangent: I learned recently that big ag companies have taken an interest in microbiome research. Supposedly they've become more pro-active because it would be fairly straightforward now to link an outbreak of antibiotic-resistant infection to farm strains if one turned out to exist. Then the blame would be on them for ignoring decades of research and they could be liable for damages / deaths.
Are there? I don't think that the USDA requires it. Although crossing strains can lead to widespread genetic changes, they are typically of a different sort. I am not sure how these genes have been introduced, where the copies have been placed, and under what promoters. I can't say that I know how well the siRNAs are conserved between strains that might be crossed, or what the other targets of the introduced siRNAs are. I am not saying that the apples aren't likely safe, they most likely are. But, I don't think it's fair to compare GMOs to cross-breeding. Still, you could probably achieve toxicity by cross-breeding if you tried.It's not like there aren't studies on chronic toxicity after approval, just not before.
In the world of academia, I mean. There's some 2,000 studies published on the effects of RoundUp / glyphosate. It's definitely a different environment from the sort of rigor required of drug trials, but there are still plenty of plant / epidemiology labs paying attention to the topic. But the changes would be documented in the approval request (I would think?). The difference is that crossing two plants has changes that would mean merging billions of bases of DNA, as opposed to a few kilobases. That sort of change in the DNA / expression / metabolic profiles would take decades to fully understand at a detailed level. And the complexity grows even more if that hybrid is then allowed to cross further with itself or either parent. And at any point in the crosses, you might put two enzymes together that form a new metabolite that wasn't seen in either host. In contrast, if you're introducing 1-2 genes, you can search them for similar targets in human / insect genomes, compare them for similarity to known allergens, and run trials between the modified and unmodified strains. And you can compare how the general technique (siRNA) tends to effect the plant and its eaters across different GMO products. I'll clarify that I'm also in favor of more testing of chronic toxicity, pre-approval. (I'm in general in favor of regulations ;) ) I just don't think it's quite as risky as one might think from first glance at the regulations.Are there? I don't think that the USDA requires it.
I am not sure how these genes have been introduced, where the copies have been placed, and under what promoters.
True enough. I suppose that's why I grew up with margarine, but wouldn't dare raise my kid on it. As for the insertion, I hope they know exactly where the insertion has taken place, and how many copies there are. They should also see if they move around before being released to the wild. Of course, the chances are that the insertions won't hit a coding section of the DNA, but my guess is that years from now, we will appreciate the majority of the non-coding DNA much more. I don't know enough about genetics to compare these insertions to changes due to cross-breeding, but I would be surprised if they weren't different in some meaningful way. Like I said, it's most likely not a big deal at all. I am not anti-GM for food in any general sense. But I am conservative on the issue. If only, because of the historical evidence of so many cases where our ignorance only came to light decades later.In the world of academia, I mean. There's some 2,000 studies published on the effects of RoundUp / glyphosate. It's definitely a different environment from the sort of rigor required of drug trials, but there are still plenty of plant / epidemiology labs paying attention to the topic.