Several weeks ago I spent lots of time arguing about the letter signed by more than 100 Nobel laureates. In the letter, they urged Greenpeace and the United Nations to support genetically modified organisms as the only way to put an end to global hunger. I feel the urge to give my opinion about almost everything, so I’m going to talk a bit (well, not a bit, it’s a 2 part post) about GMOs in general and this letter in particular.
A few things about the letter to begin with
Their web is called “Support precision agriculture”. I assume they are using this term as a euphemism referring to GMOs. Well, it’s not correct. This type of agriculture (Wikipedia) uses remote sensing, aerial photography and geographical information systems to optimize the decision making in farms. What exactly does this have to do with GMOs? Nothing, I’m afraid. Why this name? No idea.
The fact that most people blindly accepts the opinions of this people “just because” they are Nobel laureates strikes me. Appealing to authority really is not my thing. Plus, the signers are doctors, chemists, physicists and economists. There isn’t a Nobel prize in environmental science or ecology, which would be much more relevant.
Arguments for GMOs
These are the most common:
- They are harmless for human health.
- Their yields are higher.
- They are better for the environment, as pesticide use is reduced thanks to disease and pest resistant varieties (such as the Bt varieties).
- They are the only solution to global hunger and malnutrition in the third world (golden rice and vitamin A deficiency).
- They are more cost-effective for the farmers.
What does biological and agricultural science have to say about this?
Regarding the health risks of eating GMOs, there are lots of studies guaranteeing their safety (recent literature review) and even talking about “scientific consensus” about the issue. However, there are still many studies questioning this consensus and affirming that many research groups are financed or influenced by the biotechnology companies or lobby groups (reference, reference, reference).
Let’s explain some concepts before start talking about yields and environmental issues (arguments 2 and 3):
- Conventional farming: Uses pesticides and chemical fertilizers but not GMOs.
- Organic farming: No pesticides, artificial fertilizers or GMOs (some fertilizers may be accepted depending on the country’s regulations and certification).
- GM agriculture: Uses GMOs and their associated pesticides and fertilizers.
Conventional farming usually produces higher yields than organic farming, ranging from 5% to 34% higher depending on the crop, environmental conditions and management (reference, reference). But this difference can be reduced by mixing and rotating crops (reference). Plus, this decrease in yields comes with an increase in biodiversity (reference), which has a positive impact in the ecosystem and the sustainability of agriculture, as biodiversity is essential for ecological flows such as pollination or to preserve soil structure and fertility, among others (reference).
Yields increase in an indirect way compared to conventional farming when using GM agriculture, as there is less loss as a result of pests and diseases. There is no yields gene to be modified to make them higher.
Harvest losses are reduced thanks to pest resistant varieties such as Bt crops, which generate Cry proteins from Bacillus thuringiensis (a type of bacteria). These proteins are toxic for some pests larvae. This way, GMOs may reduce the use of some pesticides (reference, reference). These varieties could be really useful where pests cause big losses (reference).
However, not all GMOs are pest resistant. The so called RoundUp ready crops are another big group. These varieties tolerate the use of glyphosate, a broad spectrum herbicide, simplifying weed control. But high amounts of glyphosate residue in these plants vegetal (reference). On top of that, natural selection goes on and there are already glyphosate resistant weeds and Cry toxin resistant pests. Consequently, higher concentrations of pesticide are being used and extremely toxic chemicals such as the 2,4-D defoliator are being used again (interesting NY Times article about the broken promises of GMOs).
What about the environmental impact?
A decrease of pesticide means less pollution. But this isn’t always the case, so it’s better not to make generalizations when talking about GMOs.
Crop biodiversity is also worth considering. Lots of varieties are an insurance against bit pests and diseases. If we only grow one type of corn (or wheat, soy, rapeseed…), a new type of virus, bacteria or insect may come and kill all crops in the area. Growing different varieties minimizes this risk, as the gene pool is bigger (reference, reference).
GM farming has also a much higher carbon footprint than conventional, as the energy required during the development, production, distribution and farming is higher (reference). They rely in fossil fuels to a great extent.
Lastly, genetic pollution outside farms exists and its understudied, as it’s very difficult to take into account all the species to which the transgenic gene could potentially be naturally transferred (reference, reference, reference).
In a nutshell, even though GMOs are probably safe for human consumption (at least in the medium term) they don’t seem to reduce the environmental impact that farming has on the ecosystem. What about the social, economic and political issues? I’ll talk about them next week. Enough is enough.