Sep 11 2014

19 Years of Feeding Animals GMO Shows No Harm

Often GMO critics will argue that the biotech industry is conducting a massive experiment with our food supply by introducing genetically modified organisms. The implication is that GMOs are not adequately studied, which is at best debatable, but in a way they are correct. We can look at what has happened in the 19 years of GMO use starting in 1996 to see if there have been any adverse effects.  A newly published study, Prevalence and impacts of genetically engineered feedstuffs on livestock populations, does just that. (Full study, may be behind a paywall.)

The study authors, Van Eenennaam and Young, first review the existing literature on animal feeding studies. They then review available data on livestock outcomes to see what effect feeding them mostly GMO since 1996 has had, if any.

GMO Feeding Studies

The first regulatory hurdle for safety testing of GMOs is to establish “substantial equivalence.” Researchers must show that the genetically engineered crop is essentially the same as the parent variety in all ways except for the desired introduced genetic change. The authors report:

Over the past 20 yr, the U.S. FDA found all of the 148 GE transformation events that they evaluated to be substantially equivalent to their conventional counterparts, as have Japanese regulators for 189 submissions.

The authors point out that the same testing is not required for conventional breeding or even mutation farming. It also cannot be assumed that such techniques are without risk.

There have been instances where plants bred using classical techniques have been unsuitable for human consumption. For example, the poison α-solanine, a glycoalkaloid, was unintentionally increased to unacceptable levels in certain varieties of potato through plant breeding resulting in certain cultivars being withdrawn from the U.S. and Swedish markets due to frequently exceeding the upper safe limit for total glycoalkaloid content.

They further point out that proteins, DNA, and RNA from the food we eat are digested. Whole proteins or genes from GMO have never been detected in the tissue of animals fed GMO feed. There is also no reason to suspect that transgenic genes or proteins present any more of a health risk than the countless other proteins and genes we consume. It is therefore implausible that eating an animal fed GMO poses any health risk to humans. But what about the animals themselves?

Animal feeding studies are a mainstay of testing the safety of GMO plant varieties. The authors summarize this research:

Several recent comprehensive reviews from various authors summarize the results of food-producing animal feeding studies with the current generation of GE crops (Deb et al., 2013; Flachowsky, 2013; Flachowsky et al., 2012; Tufarelli and Laudadio, 2013; Van Eenennaam, 2013). Studies have been conducted with a variety of food-producing animals including sheep, goats, pigs, chickens, quail, cattle, water buffalo, rabbits and fish fed different GE crop varieties. The results have consistently revealed that the performance and health of GE-fed animals were comparable with those fed near isogenic non-GE lines and commercial varieties.

Some of these studies were long term, conducted up to two years, and with multiple generations of animals, 2-5 generations. A recent review of these studies by Snell et. al found:

Results from all the 24 studies do not suggest any health hazards and, in general, there were no statistically significant differences within parameters observed.

Some differences were found, but they were not biologically significant and likely represent background variation. Snell et al point out that 90 day feeding trials show the same results as long term and multigenerational trials, therefore the results of the standard 90 trials are highly reliable. In other words, doing longer term trials has so far not revealed any health risks that were missed during the shorter trials.

There are only a few outliers in the feeding trials showing possible harm, such as the now infamous Seralini study. All of these studies are of dubious methodology and are not published in peer-reviewed journals (Seralini was withdrawn and then republished without peer-review).

The bottom line is that there are many short term, long term, and multigenerational feeding trials with GMO varieties and many species of test animal, many by independent scientists, all showing that current GMOs are safe and nutritionally equivalent to their non-GMO counterparts.

One Big 19-year Experiment

Van Eenennaam and Young then approach the question of GMO feeding from a different angle. Since 1996 90-95% of animal feed in the US has been GMO. Prior to 1996 0% was GMO. This offers the opportunity for a large observational study to see if the rapid and thorough introduction of GMO feed in the US resulted in any adverse health effects for the animals.

This data is observational, meaning the authors are looking at data collected out there in the world and not part of any controlled prospective experiment. Observational data is always subject to unanticipated confounding factors. However, robust observational data is still highly useful, and has the potential to detect any clear signals.

In this case the data is particularly useful for a couple of reasons. First, the number of animals for which there is data is massive – in the billions per year. Second, the industry actually carefully tracks certain outcomes, as it is necessary or critical to their business.

For example, cattle are examined both premortem and postmortem for any abnormalities, such as tumors or signs of infection or other illness. Any sign of illness and that cow is not approved for meat. The percentage of cattle that are found to have such abnormalities is called the condemnation rate, and annual condemnation rates are kept in public databases.

The authors pooled data from various such databases for various animal industries before and after the introduction of GMO into animal feed:

Livestock production statistics for the US before and after the introduction of GE feed crops in 1986 are summarized in Table 4. In all industries, there were no obvious perturbations in production parameters over time. The available health parameters, somatic cell count (SCC; an indicator of mastitis and inflammation in the udder) in the dairy data set (Figure 1), postmortem condemnation rates in cattle (Figure 1), and postmortem condemnation rates and mortality in the poultry industry (Figure 2), all decreased (i.e., improved) over time.

So, multiple health parameters for multiple animals, including billions of animals over about 15 years showed no adverse effects from the rapid introduction of GMO animal feed. If there were any significant adverse effects from GMO it seems reasonable that it would easily show up in this data.

The reason for the background improvement in health parameters is likely due to improved genetics and handling. This slow improvement over time continued without change through the introduction of GMO.

Conclusion

We now have a large set of data, both experimental and observational, showing that genetically modified feed is safe and nutritionally equivalent to non-GMO feed. There does not appear to be any health risk to the animals, and it is even less likely that there could be any health effect on humans who eat those animals.

In order to maintain the position that GMOs are not adequately tested, or that they are harmful or risky, you have to either highly selectively cherry pick a few outliers of low scientific quality, or you have to simply deny the science.

Here is a comprehensive list of animal feeding studies. Many of these studies are independent. The list included systematic reviews, all of which conclude that GMO feed is safe.

There is as strong a scientific consensus that GMOs do not present any novel health risk, that those in current use are safe, and that they pose no health risk to animals or humans, as there is a consensus for the safety and efficacy of vaccines or that humans are contributing significantly to global warming.

16 responses so far

16 Responses to “19 Years of Feeding Animals GMO Shows No Harm”

  1. bluedevilRAon 11 Sep 2014 at 8:56 am

    The FoodBabe calls milk from GMO fed cows “Monsanto milk.” Fearmongering at its finest.

  2. DevoutCatalyston 11 Sep 2014 at 9:39 am

    “Fodder yer zorses with GMO resources”

  3. jsterritton 11 Sep 2014 at 2:24 pm

    Another excellent post on GMO safety. The observational study is of particular force and interest because the signal is so clear. Coupled with the Snell et al findings that 90 feeding trials are highly reliable, this research should help quiet the straw man arguments we’ve encountered ad nauseum in these pages about feeding studies and the misuse/abuse of the Precautionary Principle.

  4. BBBlueon 11 Sep 2014 at 4:26 pm

    Here is the anti-GMO rebuttal to the following:

    Some differences were found, but they were not biologically significant…

    “Yes they are.”

    All of these studies are of dubious methodology…

    “No they’re not.”

  5. Sylakon 11 Sep 2014 at 6:37 pm

    Good article! Those kind of study might help to steer the layman into reason. Of course people with their ideology already set are not going to change minds anyway. At least we can now refute their claim of “not enough studies”.

  6. deltaVon 11 Sep 2014 at 8:15 pm

    This is great! This is the type of study a laymen can understand and is pretty clear. I’m really looking forward to shoving this in a few people’s faces.

  7. MaryMon 11 Sep 2014 at 9:42 pm

    This is a great data set. It really would have been obvious, though, if every dairy cow and slab of bacon now had tumors. Or if all the animals had died, failing to reproduce (which is a claim we hear all the time). We’d notice.

    Another place to look is research animals. Every mouse/rat/whatever colony in the US has been chowing on GMO feed in the same manner. And these animals have fast generation times. Again–we’d know if the whole US biomedical research industry had collapsed. And these folks are specifically trained to observe problems, variations, and animal health. Either it’s a giant conspiracy of every animal tech, veterinarian, and animal researcher…or there’s no there there. Guess which it is?

  8. Yehouda Harpazon 17 Sep 2014 at 8:54 am

    While I am a strong supporter GMO, relying on studies in “sheep, goats, pigs, chickens, quail, cattle, water buffalo, rabbits and fish” and also lab animals for long-term human safety is not that convincing.

    You really need to do studies in primates, and it is a shame that (apparently) nobody does.

    In fact it is quite surprising that companies like Monsanto don’t do it themselves. How much would it cost to keep ten macaques on GMO for 10 years? Much less than they spend on lobbying, and it would be much more convincing that all of these studies together.

  9. rezistnzisfutlon 17 Sep 2014 at 10:49 pm

    Yehouda,

    No one is relying on one study to formulate opinions about that here – single study fallacy is a tactic of the anti-GMO activists in this debate. However, what it does do is add to the ever growing body of evidence that GMOs are safe to consume. Afterall, if they were as dangerous as activists claim with the myriad maladies they say GMOs cause, it would have manifested itself in livestock and other animals who consume it regularly, at times comprising the vast majority of their diet (when they’re not in open range).

    Monsanto knows better than to have such a weak study sample as 10 macaques. That being said, there simply is no hypothesis to test. That’s the problem with anti-GMO activists, they don’t understand basic science (I know you say you support GMOs, but your language is similar to anti’s).

    If Monsanto, or anyone else for that matter, had a hypothesis to test and had just cause to form a long-term study, they would do it. It would be a tremendous resource burden to do so, on the other hand, when there is little reason to have such studies done in the first place. If it were indeed required, it would need to be done on every cultivar produced.

    And where are the similar calls for safety studies for non-GMO cultivars? There is just as much cause to view those with suspicion.

  10. rezistnzisfutlon 17 Sep 2014 at 10:50 pm

    Incidentally, here’s a Forbes article on this very topic:

    http://www.forbes.com/sites/jonentine/2014/09/17/the-debate-about-gmo-safety-is-over-thanks-to-a-new-trillion-meal-study/

  11. jsterritton 18 Sep 2014 at 12:21 am

    Small cohort primate studies of GMO!? Nooooooo! A) primate testing is unnecessary (’cause of all the incidental large-scale human feeding trials and all the non-primate ones, too). B) such a small sample would be a nightmare! Recent reports show that 90 day feeding trials are the “sweet spot” for such research. Anything longer is a noise generator. Same for small sample sizes. 10!!!??? What if one dies of ennui and another of SMD (sudden monkey death)? If a third runs off with the troubled macaque in pen 4 and they both die in a botched jewel robbery, almost half your sample have died on GMO diets. Even if just one gets cancer (because let’s face it, monkeys get cancer), you’ve got a well-intentioned study showing NOTHING (except that monkey life is a very rich tapestry).

    I second Rez: no more single study fallacy fodder; from now on, only good, baby-step science building on the solid consensus we’re lucky to have.

  12. Yehouda Harpazon 18 Sep 2014 at 10:01 am

    >>>>>>>>> rezistnzisfutl

    > That being said, there simply is no hypothesis to test.

    Why not? isn’t it obvious that the hypothesis is that it will cause the macaque health problems?

    > If Monsanto, or anyone else for that matter, had a hypothesis to test and had just
    > cause to form a long-term study, they would do it.

    We certainly have an hypothesis (see above). The cause is to convince the many people that feel unsafe about eating GMO (with or without a good reason).

    > It would be a tremendous resource burden to do so

    Why?

    > And where are the similar calls for safety studies for non-GMO cultivars?

    Since there are no objections to non-GMO cultivars, you don’t need safety studies to convince people.

    > Incidentally, here’s a Forbes article on this very topic:

    Doesn’t contain anything we don’t already know.

    >>>>>>>>> jsterritt

    > A) primate testing is unnecessary (’cause of all the incidental large-scale human feeding trials and all the non-primate ones,

    What is “necessary’ is not the question. The question is it useful to convince people that feel unsafe about GMO.

    > B) such a small sample would be a nightmare!

    That is a point. You may need more than 10 animals, but to eliminate large effects it doesn’t have to be that many.

    > Recent reports show that 90 day feeding trials are the “sweet spot” for such research. Anything longer is a noise generator.

    How can they show that?
    There are pollutants that cause the effects over many years. How would a 90 day feeding trial found this kind of things?

  13. edwardBeon 18 Sep 2014 at 10:13 am

    “this research should help quiet the straw man arguments we’ve encountered ad nauseum in these pages about feeding studies and the misuse/abuse of the Precautionary Principle.”

    If only that were possible. Nothing will ever quiet anti-science idiots.

  14. jsterritton 19 Sep 2014 at 4:14 pm

    YH…

    Respectfully, I still don’t understand what your “hypothesis” is. Is it that GMOs don’t cause harm? Surely you know that experiments are not undertaken to prove negatives or (as in this case) the null hypothesis. Scientists would look for a hypothesis based on positive preclinical research to follow up on. Of course feeding studies often exist to demonstrate safety for regulatory reasons and there was a time when such studies might have been beneficial to our understanding of GMOs, but without a hypothesis to test, experiments like Seralini’s infamous one are nothing but fishing trips. The massively powered observational studies that Dr Novella writes about in this post demonstrate safety of GMO in a way that small cohort experimental studies cannot — that is to say: conclusively (or as close as you’ll ever get in science). Feeding 10 monkeys GMO Pop Tarts for 10 years sounds like the kind of poorly-designed and ethically challenged experiments that anti-GMOers love to cherry-pick: ones where the noise and signal are inextricably linked due to tiny sample size, poor controls, uncontrolled-for confounding factors, bad analytics, and the famous unpredictability of monkeys. They’re nature’s clowns.

    Also, the feeding trials of “sheep, goats, pigs, chickens, quail, cattle, water buffalo, rabbits and fish” are being done to demonstrate safety in food animals. We don’t farm and eat monkeys. You could say the same thing about rats and mice, which is another reason that feeding studies needlessly challenging the null hypothesis are ethically dubious and — in light of Van Eenennaam and Young’s review — wholly unnecessary (this review confirms the scientific consensus based on hundreds of overwhelmingly net-negative feeding and other studies).

    It is a hallmark of the anti-GMO science-ignorer to move the goalposts away from good science (i.e., the losing battle), instead calling for red herrings like unscientific studies (e.g., clinical testing absent testable hypotheses) and recasting the non-controversy of GMO safety as a matter of consumer rights or business practices. You seem sincere, yet when you say you don’t find these good studies to be “convincing,” instead proposing lousy ones in primates, I have to question whether you are just being disingenuous and only pretending to be a “strong supporter [of] GMO.”

    Taking you at your word, I hope this helps explain why the study you propose would not be “useful to convince people that feel unsafe about GMO.” For too many, even a well-powered and well-designed large-scale feeding trial of primates would just be another among thousands of studies that would be embraced or rejected based on the ideological appeal of the results of the study, not its merits.

  15. Sterling Ericssonon 21 Sep 2014 at 7:11 pm

    Of course, the anti-GMO people are now claiming the study is biased because one of the authors worked for a short time as a researcher for Monsanto 15 years ago.

  16. grabulaon 21 Sep 2014 at 10:00 pm

    @YH

    “We certainly have an hypothesis (see above). The cause is to convince the many people that feel unsafe about eating GMO (with or without a good reason). ”

    “Since there are no objections to non-GMO cultivars, you don’t need safety studies to convince people.”

    “What is “necessary’ is not the question. The question is it useful to convince people that feel unsafe about GMO.”

    At what point does GMO-denial become moot when it comes to the science? What’s the critical mass here you think we need to reach? There will ALWAYS be those who deny the safety of GMO, because of the human brains ability to make the naturalistic fallacy.
    Doing science just to convince people of something is wasteful. Once the evidence for safety of GMO is provided by science then it becomes less and less necessary to continue to dump resources into it. At some point GMO’s are utilized en masse and you get a de facto study of the safety in human beings.
    What I’m saying is convincing people who already don’t understand the science isn’t a good reason to spend time and energy trying to convince them through the science they can’t be bothered to understand.

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