What follows is the second in my series of responses to Greenpeace’s True Food Guide Questions and Answers. This one focuses on question number 6: “How do GE crops affect the environment?”
As you read this, it might seem that I am turning the facts around. Please remember that I’m just trying to fill in the other half of the story. If I was to write a paper on the possible effects of GM crops, I would include information on both positive and negative effects. I understand that it isn’t Greenpeace’s goal to provide both sides of the story, but they really should, if they want to help consumers make good decisions. Instead, they are only providing half of the story, as well as half truths and some outright lies, and effectively telling people what to think, instead of responsibly spreading information. No matter your views, this is just wrong! If you’d like to know more details about any of these points, or if you would like to see some peer-reviewed research to back anything up, just let me know in a comment.
On to the response!
There is growing scientific evidence that GE crops are harmful to biodiversity and the environment.
Where is this evidence? Strangely, no specific examples are given.
Furthermore, once GE crops are released into the environment they cannot be recalled. As living organisms they can reproduce and pollute indefinitely.
I can only imagine that they are referring to gene flow from transgenic plants to non-transgenic plants. This is actually a rather complex subject, because we every GM crop is not the same. Some GM plants are a lot easier to contain than others, and some need less containment than others. Variables include the new traits they contain, inherent traits in the species, the location, and the farming situation. To give you an idea of the wide range of individual situations, here are a few real world examples of GM plants that are either already available or in various phases of research, plus a little speculation about related situations that have not yet arisen.
Consider poplar trees engineered with a gene from rabbits to pick up toxins like trichloroethylene from contaminated soil then metabolize them into harmless compounds. Since poplar trees don’t flower until they are about 5 years old, they can be harvested after 4 years, before they even have a chance to produce pollen. What if a tree was allowed to flower, and pollen spread onto nearby poplars? This gene has no benefit for natural plants, so it won’t be selected for in future generations, and will simply remain in the population at low levels. It won’t cause any problems for plants that happen to end up with the gene, and nearby soils will actually be improved, not harmed. In the case of genes such as these, that benefit the environment, we might actually consider letting the gene spread into the natural population on purpose. Some candidate traits for intended release would be resistance to insects or disease in cases where the natural plant population would be wiped out without human intervention (such as with Whitebark Pine and Emerald Ash Borer).
Consider banana plants engineered to produce an antigen that will be used for edible vaccinations against Hepatitis B. Banana trees actually don’t reproduce sexually, instead propagating vegetatively, so there is no gene flow with other plants. Like the poplars, plants that do have the gene don’t have any benefits over plants that do not, but the gene does not harm the plants or nearby environment either. If the antibody was proposed to be put into a plant that does reproduce sexually, then we would need to consider ways to prevent unintended pollination, such as only growing the plants in greenhouses, or emasculating the flowers of the plants so the pollen could not spread. Some crops that do reproduce sexually, such as potato, are actually grown from tubers so “contamination” of seed would not be a problem unless there were wild relatives nearby.
Consider corn engineered with the Bt toxin as protection against certain herbivorous insects (for details on how the Bt toxin works, please see The Butterfly Affected from Canada’s Virtual Science Fair). Corn, unlike bananas, does reproduce sexually with copious amounts of pollen. Unlike poplars, corn is harvested after pollination. The Bt gene does confer an advantage to plants, so would be selected for in future generations. This presents a big problem, especially if the gene spreads to weedy relatives of corn like tripsacum or to other corn fields, but there are quite a few different ways to solve it. I’ve written about some of these ways in a post titled Gene Flow, IP, and the Terminator. To summarize, though, corn pollen is really heavy so doesn’t travel far. It can be contained by simply planting a border of another type of corn around it to “soak up” pollen, by planting it a certain distance away from other corn fields or native populations, or by using plants that produce sterile pollen. Because of the possibility of pollen flow, however small it might actually be, corn really isn’t a good choice for production of certain compounds like pharmaceuticals – plants that have limited or no sexual reproduction are much better, for the reasons discussed above.
There is one more important detail regarding gene flow that few people are talking about. We should be worried not about transgenes, but gene flow from all domestic crops to wild populations of that crop or relatives of the crop. I wrote about this in some detail in a post called Contaminated. To summarize, wild populations have a much greater degree of genetic diversity than domestic fields. They have lots of genes that allow the population to react over time to things like disease and drought. These wild populations are a resource for plant breeders and genetic engineers who might be looking for beneficial traits. When domesticated pollen fertilizes wild relatives, that genetic diversity becomes diluted. If this was a one time event, then the population would recover – the hybrid plants usually won’t be at an advantage over their 100% wild neighbors. However, when the wild population is fertilized with domestic pollen year after year, the population dynamics can change quickly, especially for annuals. I’m not saying that we shouldn’t have domesticated crops, but we might want to rethink growing any domestic crops without safeguards near wild populations.
The introduction of herbicide-tolerant GE crops to the US has resulted in a huge increase in both herbicide use, and the incidence of herbicide-resistant weeds.
Nope. The introduction of herbicide resistant crops has decreased overall herbicide use, and more importantly, has decreased the use of more toxic herbicides like atrazine (deadly to bees and fish) in favor of the relatively benign glyphosate, which binds tightly to soil then degrades. Herbicide resistant crops have also allowed farmers to avoid tilling their fields (a physical weed control method), decreasing the release of greenhouse gases from the soil and decreasing removal of topsoil by water and wind. Fields of herbicide resistant crops have lower levels of pesticide in their runoff than conventional crops, according to a February 2008 study done by the USDA. However, even though it is comparatively better than other herbicides, glyphosate (and its typical additives) does have its own issues (see paragraphs on toxicity below).
All herbicides (whether used in conjunction with resistant crops or not) have increased probabilities of weed resistance developing the longer that they are used. Ideally, farmers would use complex rotation patterns, switching herbicides (and crops, and insecticides, and…) each year to prevent resistance from developing. Even better, they could integrate some natural weed control methods, such as planting grass between rows of crops, or moving away from they typical annual crops of corn and soy (and to a lesser extent, canola), although I see this as less likely. Regardless of how they are using
Roundup, the herbicide sold by Monsanto in conjunction with its Roundup Ready GE crops, has been shown to be a potential endocrine disrupter – that is, it could interfere with our hormones. It is also toxic to certain wildlife, such as tadpoles.
As I said above, glyphosate is a relatively benign herbicide. It very well could be an endocrine disruptor (there haven’t been enough studies yet to prove this), but again, it’s far far better than other herbicides. If these chemicals are indeed bad, then we need to restrict the use of the chemicals. It has nothing to do with genetic engineering, and everything to do with farming methods.
The introduction of GE canola has been shown to have serious biodiversity impacts. For example, a UK government study found there were 24% fewer butterflies in the margins of GE canola fields because there were fewer weed flowers (and hence nectar) for them to feed on. In addition, there were fewer seeds for birds.
This quote is presumably referring to herbicide resistant canola, and it makes a lot of sense. Less weeds producing fewer flowers producing nectar and fewer weeds producing seed for fewer butterflies and fewer weed seed eating birds. I haven’t seen the study, but I bet they compared a field sprayed with herbicide to one that was not sprayed with herbicide. The decrease in biodiversity has nothing to do with genetic engineering and everything to do with herbicide. To me, this speaks more against certain farming methods than against GM crops. These farming methods were developed to produce copious amounts of grain, which is used to feed animals. It’s really simple – if you want to improve biodiversity, fight against conventional farming methods by avoiding grain fed meat and animal products. Again, for emphasis, this has nothing to do with genetic engineering and everything to do with factory farming!
The use of Roundup on GE soy has also been shown to have an adverse impact on soil health, leading to reduced amounts of beneficial nitrogen-fixing bacteria in the soil.
Sure, some soil bacteria are affected by herbicides, while a few types survive, which can reduce biodiversity. This is a problem, but again – not a genetic engineering issue (see above).
Insect-resistant GE crops (termed Bt crops) have been shown to be toxic to “non-target” organisms (such as butterflies) and beneficial insects (such as green lacewings).
This is true – sort of. If, in carefully controlled laboratory settings, you force feed a butterfly large amounts of pollen from a transgenic plant expressing Bt from a constitutive promoter, then yes, the butterfly will die. However, butterflies don’t eat pollen, and generally aren’t even near corn field when they are shedding pollen (again, see The Butterfly Affected). Neither do lacewings. Both butterflies and lacewings, along with a host of other beneficial insects, are certainly susceptible to broad spectrum insecticides, which Bt can and does decrease use of. There are more beneficial insects in number and in diversity in Bt fields than in conventional non-Bt fields. And, using tissue specific promoters solves the problem of Bt in pollen.
They also threaten soil and water ecosystems, since many Bt crops secrete Bt toxins from the root into the soil.
Some Bt crops are designed to express Bt in the roots, but do not “secrete Bt toxins” – it stays in the roots. Root expression of Bt is specifically used in corn to combat root borer, which can devastate fields. The amount of Bt toxin that ends up in the soil and subsequently in the water is virtually nothing, especially when we compare it to regular insecticide run off.
Agricultural wastes from Bt maize have been identified entering water courses.
Plant matter from all sorts of crops has “been identified entering water courses”. But this essentially means nothing, except that maybe we should harvest these waste materials for biofuels (see the second half of my post Even scientists make mistakes for more). There is no evidence that Bt leaches from these residues.
Bt crops are intended to prevent the need for three applications of insecticide.
Bt crops do prevent the need for insecticide applications that are needed for the particular insect pest that is susceptible to the particular version of the Bt toxin that is used. They aren’t a silver bullet and should be used in conjunction with a Integrated Pest Management plan (and preferably crop rotations and non-Bt refuges to prevent insect resistance).
Yet Bt maize varieties continuously release a toxin into the environment in quantities 3000-5000 times higher than the sprays used for non-GM farming.
Bt crops do not “continuously release a toxin into the environment”. Instead, they keep the toxin safely locked away in plant tissues, where it can only affect insects that try to eat the plants. This is very much preferred to insect control methods that do not discriminate.
In 1935, some 3000 imported cane toads were introduced in north Queensland to control native cane beetle populations. Today, cane toad numbers exceed 200 million, spreading into neighbouring states and threatening local biodiversity.
In 1935, we made a lot of bad decisions. We just didn’t have the experience we do now.
We learnt an important lesson from this – playing around with natural ecosystems can have unpredictable effects which are extremely difficult to undo. This is just as true for the genetic engineering of crops.
I understand the point that they are trying to make here. Unfortunately, we have been “playing around with natural ecosystems” intentionally and unintentionally for a long time. The biggest instance of our “playing around” is the number of humans on the earth. We will not be able to feed every person with existing farming methods, even if we assume perfect distribution. We are failing to satisfy the daily nutritional needs of every person even today! As the number of people on the planet increases, the disparity will only get worse. I refuse to accept a scenario which includes a large human die off or to write off human suffering. If a GM crop like drought tolerant rice or Bt eggplant can keep people from starving, with little or no negative impact on the environment, then we have a moral imperative to make sure that they have them. This might seem a little off topic, but this point is worthy of consideration. It’s easy for a well-fed (or over-fed) American, European, or Australian to put their nose up at this technology, but it’s not about us. We can not make the decision for the developing world, or even for the developed world. We need to stop the conceit and deceit of claims that genetic engineering is worse than all of the other things we do. Farming itself (no matter how organic or biointensive) is unnatural and irreparably changes the landscape, but very few people are calling for the end of farming. We need to move ahead responsibly, which we can best do through cooperation and level headedness.
In fact, the risks associated with GE crops may be greater – pollination through open air exacerbates the potential for contamination and hampers containment.
I covered this at the beginning of this post.
To date no assessments of the environmental impacts of GE crops have been undertaken in Australia. However, one thing is certain – once harmful effects become apparent, it will already be too late.
Why isn’t Greenpeace funding studies to assess the environmental impacts? As soon as there was good data (from sound, peer-reviewed research) showing problems with any particular GM crop, deregulation of that crop would be denied. They could put their money where their mouth is. Instead, they make vague claims.