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Anytime you hear Genetically Modified Organisms (GMO) come up, someone always pipes in that it's perfectly safe because we've been doing it for thousands of years through selective breeding. Intuitively this sounds a lot like saying we've had solar power for thousands of years via chlorophyll (ie, true but not relevant to the real issue).

So specifically what risks exist with GMOs that do not exist from selective breeding?

Updating just in case it's not absolutely clear what I'm asking. There's almost a 0% chance that GMO is better in every single way than selective breeding without introducing any new risks at all, so what are the new risks?

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Is this a question specific to plants in agriculture, or does it include plants made for industrial products (potatoes for glue), animals for food, microbiology (production of Insulin for pharmacy)? –  user unknown Mar 11 '11 at 3:34

6 Answers 6

up vote 17 down vote accepted

The major risk associated with GMOs is due to the lack of "familiarity". This term means that if natural breeding product are similar to each other ("familiar"), GMOs aren't - and this is especially true in the cases of crossing between plant and animal genes.

This is a generic known principle which also applies to completely natural phenomena, like the introduction of the cold virus in central America in the XV century. So - lack of familiarity can introduce severe disruptions in the ecosystem.

This said, we do not know if there are any real risks with GMOs. But entities like the European Union have decided to take a very careful approach due to the possible consequences.

where there is a threat of significant reduction or loss of biological diversity, lack of full scientific certainty should not be used as a reason for postponing measures to avoid or minimise such a threat

Furthermore some direct risks are the following:

The ecological probabilities of harm focus on weediness, spread of the transgene by either vertical or horizontal gene flow, and the potential for any unintended, or pleiotropic, effects.

To know more you can refer to the following (presumably peer-reviewed) very complete and referenced paper:


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Nobody is making food to be eaten that mixes plant and animal genes. –  Django Reinhardt Apr 16 '11 at 14:36
@DjangoReinhardt, Scientists have created a frost-resistant tomato plant by adding an antifreeze gene from a cold-water fish to it. Sounds like mixing plant and animal genes to me - and somewhat worrisome, considering antifreeze is usually poisonous. Then again, tomatoes used to be considered poisonous... –  John C Nov 24 '11 at 13:15
@django, the question is about GMO in general, not food in particular. –  Sklivvz Nov 25 '11 at 8:26
@John C, So just to recap: There's no commercially available food anywhere in the world that mixes fish and plant genes. This means that nobody is making food to be eaten that contains those genes. Right? –  Django Reinhardt Nov 30 '11 at 7:34
@JohnC: the antifreeze you put in your car may be poisonous. It does not have anything to do with genes that confere cold-resistance, of course –  nico Apr 14 '12 at 10:50

There is a specific risk of litigation with GMOs (particularly ones bred through pollination) that does not exist with classical eugenics, or selective breeding.

Case in point would be the various lawsuits documented in Monsanto vs. U.S. Farmers, wherein as of 2005 more than 15 million dollars had been awarded to Monsanto for infringements of their products (not counting the 525 settlements as of 1999). Obviously these numbers are dated, but I doubt the occurence of these lawsuits have declined.

A frequent case for consideration is Percy Schmeiser whose case focused on Monsanto's claim of patent infringement and (the counter-claim) "whether Monsanto would be held responsible for 'genetic engineering crop contamination'". Essentially, genetic dangers aside, there is a danger of growing a field of non-GMO corn next to a field of GMO corn insofar as, if the two cross-pollinate, and you replant the seeds, Monsanto may show up with a cease-and-desist letter.

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There's a lot of misinformation out there regarding the Schmeiser case. He planted Roundup-Ready canola one year, saved the seed and planted it the next year (which is explicitly against the license granted with the purchase of the Roundup-Ready canola), and was subsequently sued by Monsanto. He believed that he should be able to grow the seed without paying them and he also sold some of the seed the next year, and the Supreme Court disagreed. Here's the judgement for further reading. –  tak Apr 16 '11 at 18:17
@tak while interesting, I would not over-generalize and consider the distaste for that ruling ((or precedent) misinformation. On the one hand, no TOS was signed with respect to using the seeds he did sow, on the other much of the sample obtained (3 samples from 9 plots) yielded wildly varying results in terms of their being Monsanto derived at all (thereby, despite the admissibility by common law, their 0-98% "Roundup Ready" status indicates Monsanto was on shakier ground than the ruling indicates). –  mfg Apr 16 '11 at 19:16
Moreover, the reason the case remains a controversial finding is due to not only those two points, nor that Schmeiser was some saint or hapless victim- but rather because of the likelihood that even if one of the nine plots was 100% Round-up Ready, and taken care of as such; the remaining 8 fields are still likely to become infected by cross-pollination inadvertantly and any farmer would likely reap the associated ills. –  mfg Apr 16 '11 at 19:19
Several samples were grown from seed by the defendant and the plaintiffs, and only the plants grown by the defendant had less than 98% glyphosate resistant plants. They also ran PCR tests for the patented resistance gene, which also were positive on all samples. If the seeds in question were the result of cross-pollination, it would be expected that the ratio of resistant to susceptible plants would be close to 50%, and definitely not 98%. The ruling goes over the evidence and is pretty clear on all this. –  tak Apr 16 '11 at 21:44
From the ruling: "The seeds provided to [Mr. Schmeiser] from the 1997 sample taken of plants growing along the road allowances of fields 2 and 5, demonstrated that the canola plants growing there were not the result of pollen movement into those fields, or out crossing between glyphosate-resistant and susceptible plants. Rather, in [the expert witness's] view, the high percentage of glyphosate-tolerant plants, among those which had germinated, indicated they were grown from commercial Roundup Ready canola seed." –  tak Apr 16 '11 at 21:45

Okay, round 2 at answering this question. Jonas's answer on a related question, quotes a highly relevant section of a FDA article.

Since newly introduced substances in foods derived using recombinant DNA techniques would be proteins, fats or carbohydrates, we then examined the safety questions that should be addressed before products reach the market. We identified four broad safety issues that should be evaluated: (consumption; (2) the need to ensure that the changes in the food, such as the level of natural toxins in the food, if any, stay within normal safe levels; (3) the need to ensure that significant nutrients stay within normal range; and (4) the need to analyze the potential for introduced proteins to cause allergic reactions. We incorporated these and other issues into a comprehensive guidance to industry that is central to our policy.

So, there are real risks and I don't doubt that GM will eventually cause some issues. Biological systems are inherently complex and things interact in all kinds of strange ways. People have all kinds of strange allergies. Even though the FDA has given this matter careful consideration, it isn't perfect and organisations in other countries may be less stringent. However, the same could be said about various chemicals and medicine. Things have gone wrong a number of times, but I believe that they have been beneficial to society as a whole. I think it will be the same with GM, except the risks are much less.

What worries me though is how many people reject offhand the possibility of there being risks. Sure there is a lot of alarmism, but we can't reject legitimate concerns based purely on contempt for anti-GM activists. I think GM can be used responsibly, but only if we respect the power that we hold and the limits of our knowledge.

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Does this address the question, which asks for risks that are not also in selective breeding? (I am desperately wracking my brain for the selectively-bred crop which was hastily withdrawn from the market when it was discovered to have abnormally high levels of "natural toxins". Even if I remember it, it would make a good question.) –  Oddthinking Feb 23 '12 at 5:12
@Oddthinking: In the FDA's opinion, these risks either don't exist with selective breeding or don't exist to the same degree. On the contrary, do you have any evidence that the FDA's suggestion that genetic modification may result in abnormally high toxins isn't justified, other than mere skepticism? –  Casebash Feb 23 '12 at 6:26
To clarify: I am wondering if the risks of selective breeding aren't also present. While your argument (a politically-influenced but science-based government department asserts it) is only moderately strong, my idea is based on a rumour I can't even remember, so your argument is more persuasive so far. –  Oddthinking Feb 23 '12 at 9:26
@Oddthinking: You might be able to get an answer biology.stackexchange.com. Sorry, I misread what you were saying. Yes, the question does asks for risks that aren't present with selective breeding, but it would be misleading to answer that there are "no risks that don't exist with selective breeding" without mentioning risks that it enhances. It would be far too easy for someone to misread that as GMO having exactly the same risks as normal organisms –  Casebash Feb 23 '12 at 9:57
@Oddthinking - not sure about crops per se, but they kinda stopped using Beladonna and opium for cosmetics/medicinal purposes in raw form over some safety concerns. –  DVK Apr 23 '13 at 19:01

In the latest "Skeptics' Guide To The Universe" episode, Kevin Folta said that you have much more control over the outcome of the genetic material using GMO, as opposed to "breeding by chance" (classical) - which is acceptable by public but gives no controllable results. I would say, GMO is more safe, and my source is intervew with Dr Folta :)

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How does control over outcome equate with lessend risk or higher safety? –  mfg Feb 25 '11 at 15:32
mfg: You're asking how introducing a single gene with known function differs from randomly introducing unknown number of unknown genes with unknown functions? –  Mchl Mar 2 '11 at 17:45
@Mchl: Yes, that's exactly what @mfg is asking. Does greater control over outcome lessen risk? Only if the outcome the being aimed for is, in fact, less risky. (There are many cases where increased human control has lessened risk - smallpox, for example. There are also cases where increased human control increases risk - chemical and biological industrial accidents happen, and kill people, in ways not otherwise likely.) I am neutral on the subject of GMOs, because I know nothing about it. But an answer to this question calls for evidence. What are the risks? Measured how? –  Tynam Apr 3 '11 at 15:32
-1: Because this is clearly fallacious reasoning. As Tynam said, more control only equals more safety if you are trying to do the same thing. The whole point of GM is to produce organisms that are different –  Casebash Feb 23 '12 at 2:28

Genetic engineering is a bit like cars. Humans always moved from place to place. Having cars allows us to go faster.

That's both good and bad. It allows us to save time but also increases the accident rate.

For a longer analysis the Long Now foundation hosted a high level debate about GMO with synthetic biology.

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The argument has long been made that the gmo that are put in the plants to protect them will not be able to withstand the human digestive system. A study done at the University of Sherbrooke found that not only did they survive and circulate in the body, they also passed to the fetuses of pregnant women.


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The article you cite refers to specific pesticides that are also expressed by specific GMOs, e.g. Bt-Maize. The article has been met with quite some criticism, they just assume that the source of the pesticides is from GMOs, though the same pesticide is also used in organic agriculture. –  Fabian Nov 22 '11 at 16:51

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