Monday, April 2, 2007

A GM-food primer. Not all GM-foods are created equal...

Last week's furor over genetically modified (GM) plants killing bees got me inspired to write a bit about genetic modifications. It's something I know a little about, as my day job is that of an academic post-doc in one of the larger medical schools in the U.S. I spend my days genetically modifying bacteria so that I can understand better how they work. Doesn't that mean that I'm biased? (I got called an industry stooge for defending GM-plants). Well, perhaps. But I earn so little that I have no money invested in biotech stocks (really, I have very little money invested in anything besides my house), so at least I have no financial horses in the race. And the work I'm talking about isn't really related to my own work. I'm just sufficiently educated in the field that I have a clue.

So, what did the Spiegel article mean when the author accused GM-plants of being responsible for the recent bee die-off? (a claim I debunk here and here). Do we need to worry that all GM-plants are killing bees? Well, no. They were talking about a particular, common modification called BT.

BT stands for Bacillus thuringiensis, which is just the latin name for a particular bacterium that kills insects. People started taking advantage of this bacterium over 70 years ago, by sprinkling dried bacteria onto plants to protect them from insects. (And even today, organic farmers consider this an acceptable pesticide that they are allowed to use). Indeed, the fact that it is a bacterium that only kills insects is of great use to us, as it is totally safe for humans.

Bacillus thuringiensis kills particular insects by virtue of a single protein that it makes. One gene specifies the creation of this protein. If you remove the gene from the bacterium, it no longer kills insects. What genetic engineers have done is to take the gene from bacteria, and place it into plants, particularly corn and cotton. (The insects that afflict corn and cotton growers are particularly susceptible to death by BT). So this one single gene is transferred from B. thuringiensis into corn or cotton, and allows the plant to kill insects that eat the corn or cotton.

Do we need to worry about BT harming people? No. In literally decades of study of B. thuringiensis, it has been shown that pure BT-toxin is no more harmful to people than table salt. You couldn't eat corn fast enough to accumulate enough toxin to give you so much as a bellyache (it is readily degradable in the stomach). And safety studies over the last 15 years have shown that BT-corn behaves no differently than B. thuringiensis sprayed on corn. Really, as much as you can say anything is safe, BT-corn is safe.

What about BT-corn harming bees? Well, folks have looked for this, too. But bees don't eat corn, and they don't pollinate corn. Indeed the dosage needed to kill bees is quite different than that of caterpillars and beetles, and the symptoms are rather different than what has been seen in the bee die-offs seen recently.

But, let's imagine for a moment that BT-corn is responsible for the bee die-off. Is this an indictment of genetically modified food? Not at all, it would be an indictment of BT-corn. There are all kinds of other modifications that people are working on that wouldn't have any kind of effect on insect populations. Take for example, coffee, genetically modified to not make caffeine. Or peanuts genetically-modified to remove the allergens. These are kinds of things that people are working on today, and one wouldn't expect there to be any kind of bad effects to people or plants by making these changes.

What I'm basically trying to say here is, when someone tells you they're talking about GM-food, it makes about as much sense to make general conclusions about it as it does when someone talks about "chemicals". Chemicals range in quality from vinegar to phenol to sulfuric acid. When speaking of the danger posed by these chemicals, there is quite a range of possibilities. So, too, with GM-foods. Each GM-food poses it's own risks and benefits, and current GM-foods, the risks seem rather small and the rewards rather large. I'll post in the future on some of the risks posed by newer GM-foods. But let's take these things on a case-by-case basis, shall we?



Skeptico said...

Great article – thanks. It’s good to see some rational discussion of GMOs from someone who actually knows what they are talking about. Pretty soon you’ll be getting comments from the “ban all GMOs” and “you’re just a pharma shill” crowd. Good luck with them. ;-)

The Factician said...

Heh, I've already been called a pharma shill over at How The World Works at Pretty funny, really, given that I work in an academic lab. Ah well, I understand that Orac gets called a pharma shill pretty regularly, and he runs an academic lab...

Pat said...

A point that maybe you could or your commenters could shed some light on.

It makes sense from a business perspective to make gm crops sterile so that growers have to come back to you for seed. Is it necessary for gm crops to be sterile?

The Factician said...


I think you're referring to "terminator" technology. A few points on that:

Terminator technology was first proposed in the late 80s, early 90s. Some folks suggested it would be a good idea to make GM-seeds sterile without a particular additive to prevent genetic contamination of nearby crops. Sounds like a good idea, right? Well, other folks suggested this would also make it possible for biotech companies to lockdown the seeds and prevent anyone from growing their own seeds. That said, it was a PR nightmare for biotech companies, and to my knowledge, no one ever deveolped it (though it is an internet myth to this day that terminator technology exists). It has never been implemented, it's only been proposed.

It's kind of sad that no one ever implemented it. It would be the perfect tool to keep pharma crops under control, and keep them from contaminating the food supply. And it would be a pretty lousy way to prevent people from growing their own seeds, as it would be relatively easy for molecular biologists to "crack" the terminator code, and provide the chemical to make seeds to farmers (much more easily and cheaply than developing new generations of terminator technology). It would be an even bigger nightmare than software folks have preventing pirates. My opinion is that terminator technology, for the right purposes, would be a grand idea.

Right now the only thing preventing farmers from planting their own seeds of GM-crops is intellectual property laws in the U.S. (in places like India, people use "pirate" seeds relatively frequently). It would be relatively easy for American farmers to flout the intellectual property laws, but it would also be relatively likely that they would get caught. Much like software, businesses don't tend to use pirate software because if they get caught, they get sued out of existence. Individual consumers do it, because it's not worth the time of software companies to go after small fish. Same thing for biotech seeds and farmers. If you grew it in your garden, no biggie. But a farmer would likely get caught and sued out of existence.

Hope this helps.

Pat said...

Thanks factician. Exactly the kind of information I was looking for.

Joanne said...

You mess with Mother Nature, what do you expect.

Anonymous said...

Why don't you reference this study in your article?

Monsanto's GM corn MON863 shows kidney, liver toxicity in animal studies

and yes, you are likely a paid (academic) shill.

The Factician said...

Thank you, Anonymous, for pointing me towards that paper. I had read the news releases, but you inspired me to actually look up the paper. I assume you're referring to Arch. Environ. Contam. Toxicol. 52, 596–602 (2007). It's a striking example of badly interpreted experimental biology.

Perhaps I'll write a longer post about it later (if it comes up again) but I'll post my major complaints about it here. First off, the effects that they claim to see on body weight are so small as to be negligible. They claim they are statistically significant, but have to use some pretty fancy statistics to show that. As one of my mentors told me, "Statistics are a substitute for not having enough data".

My second problem is that they use a battery of tests (58 tests done on multiple groups to do 494 comparisons) and find that in 40 of them there is a difference. Sounds frightening, until you realize that all the animals were treated differently, one would expect at least 25 of them to behave differently.

But, if you're inclined to believe their model that BT-corn is toxic, why do they have absolutely no dose dependence to their observations? More BT-corn often shows *less* symptoms rather than more. That suggests strongly that these are random distributions.

So, in conclusion, they see *tiny* effects that are almost certainly due to random distributions.

Amax said...

I was under the impression that the worry with the bees and BT corn was from the high fructose corn-syrup fed to bees as a food supplement. Does the BT survive the processing of corn to corn syrup?

The Factician said...


Two reasons to think it's not the BT corn syrup (though I doubt there's much BT in corn syrup - as corn syrup is largely a carbohydrate soup, and BT is a protein - I can't say for sure that there is no BT in corn syrup). Anyone else out there no about any data on this?

That said, let's imagine that there is BT in corn syrup produced from BT-corn. Given that Colony Collapse Disorder is occurring in countries where BT-corn is illegal (for example, Germany) it is highly unlikely that BT-corn syrup is to blame.

The second reason to think BT-corn is not the likely culprit is that the entomologists of the Colony Collapse Disorder Working Group have said that the manner in which a bee would die if poisoned with BT is quite different from the manner that they have died (i.e. the forensic evidence points to another cause).

Recent experiments have shown that you can repopulate a dead bee colony if you irradiate the hive, suggesting that the culprit is a living agent - a microbe, more than likely (the irradiation kills whatever the microbe is that has infected the hive).

The Factician said...


I found this paper: Food Research International 39 (2006) 250–255 where they were unable to detect any carryover of BT into corn syrup using an assay that had a lower detection limit of 0.1 ppm. Hope this helps.

Anonymous said...

First, bees absolutely gather the pollen from corn. Growing up, my parents grew small amounts of corn on our land here in Texas, and there were always bees gathering pollen from the corn tassels.

Second here is a great article about Bt corn exsposure in the Phillipines.

Here is a BT fact sheet from Oregon state university.

The findings do not state that BT is highly toxic to mammals, but it is not 100 percent safe either. There is no data on the effects that BT has on reproductive health, and the research states that "undesirable chemicals produced by BT may cause changes in genetic material." There are also no studies that evaluate the long term effects that ingesting BT corn, or any GMO for that matter, have on the the human body. It is true that BT has been used by organics farmers TOPICALLY as a pesticide, but when a plant is making the pesticide within its own genes IT IS NOT THE SAME, AND THE CUMULATIVE EFFECTS OVER A PERIOD OF SEVERAL YEARS ARE NOT KNOWN. The mixing of genetic material across species is a dangerous and unnatural business. New amino acids and proteins are created that are not recognized by our bodies when ingested.

Pollen from GM crops has also been linked to the increase and severity of allergies. My personal physician and many others are suspect of GM pollen as the reason they have seen and explosion in allergies here in Texas. My physician says are bodies are literally freaking out as we inhale this stuff.

Many European countries no longer allow GMO crops to be grown or imported, because the people there are aware that they are dangerous, and that there is no way to contain cross pollination and infection of native crops. Ireland recently recalled rice from the US that was imported because HUMAN GENES were found in the rice. The company that farmed the rice swore that their rice was not GMO, but their crops were infected by cross pollination with a nearby GMO crop.

GM is simply a way of patenting our food supply. There are several farmers whose crops have been infected by GMO crops. GM companies, of which MONSANTO is the biggest culprit, conduct their GM experiments open air with absolutely no containment. They send investigators to nearby farmers fields, take samples of their crops, and if their crops contain the patented gene, the farmers are sued for stealing the patent. Here are some articles documenting this.

The fact is, that cockroach genes and hepatitis vaccines should not be put into potatoes, spider genes should not be put into tomatoes, and pesticides should not be put INSIDE corn. You have no idea whether or not the bt corn is affecting bees. I 100% believe that you are either a shill, or just a person who is failing to look toward the future at the big picture.

And to comment on another blog you wrote, the FDA does not need to regulate supplements. Big pharma wants this to happen because herbs cannot be patented, and many do provide significant benefits as an alternative to drugs. Drugs approved by the FDA have killed or permanently injured far more people that herbal supplements ever have or ever will. I am actually a chemist that works for pharmaceutical companies, and its all about money, bottom line, period. Much of the science that goes into creating new drugs is rushed and just plain poor. I would much rather take an herb that has been around for hundreds of years than a drug that has been around for only a few.

Anonymous said...

Anonymous here again - you replied poorly to the liver toxicity study I linked to above. The issue isn't the weight loss, Mr. Shill, but rather liver toxicity:

"Triglycerides increased by 24–40% in females (either at week 14, dose 11% or at week 5, dose 33%, respectively); urine phosphorus and sodium excretions diminished in males by 31–35% (week 14, dose 33%) for the most important results significantly linked to the treatment in comparison to seven diets tested. Longer experiments are essential in order to indicate the real nature and extent of the possible pathology; with the present data it cannot be concluded that GM corn MON863 is a safe product."

Perhaps you can answer to these studies as well? There's a video of the report findings for your viewing pleasure.

How much do the PR firms pay you, anyways?

The Factician said...

Mr./Ms. Anonymous:

Hmmm... my own blog seems to have eaten my reply...

Okay, I have several problems with the study that you link to. I already described the problems above, but I'll try to break it down further for you.

1. Small sample size is more likely to be messed up by random fluctuations.

2. Large number of tests done. If you do 100 tests, you would expect *just by random fluctuation* that 5 of them will come out statistically different from the control at a level of p < 0.05.

3. Dose independence. As they increase dosages, liver triglycerides reverse their changes. (i.e. at low dose they see a level that is *slightly*. lower than control, at higher dose it is higher than control). At earlier timepoint they see the opposite. This suggests rather strongly that what they are seeing is random fluctuation (and if I were the author of that report, I wouldn't try to make any conclusions about that without doing followup studies).

4. This paper disagrees with mountains of literature, (and other experiments have been much better done).

5. The authors misrepresent several of the papers they reference in their study. That doesn't mean that they are dishonest (they could be just incompetent). Anyway, it doesn't lend any more credence to their interpretation of the data...

I hope this helps outline why I have problems with the study that you cite.

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