Over the past decade, Americans have become more and more informed about where their food comes from. That's a great thing, but it has led to a vocal, passionate debate about the role that genetically modified organisms (GMOs) -- in particular GM seeds -- play in our diet.
While I tend to sympathize with the view that we shouldn't be tinkering with nature's wisdom within the confines of a laboratory, it's important to look at the real benefits and most pressing threats that GMOs pose to our population.
Moving beyond the broad "Don't mess with nature" argument, here are three key reasons GMOs could be harmful over the long run.
Super bugs and weeds
GMOs are engineered to have one of two key traits. In some cases (i.e., Bt corn), the crop is infused with a chemical that is only toxic to certain pests; in other cases, it is made so that when pesticides are applied, the crop itself is unharmed.
Either way, the same basic strategy applies: Kill off the undesirable forms of life (pests and/or weeds) while maintaining the integrity of the crop that we want to harvest. But already, problems are arising from this paradigm.
For instance, in 2011, Iowa scientists found rootworms that were able to withstand toxins that were a part of Monsanto's (NYSE: MON ) Bt corn. Though farmers are supposed to grow non-GMO refuse areas to guarantee superbugs are less common, it hasn't stopped them from developing. That has led some farmers to seek similar seeds from Monsanto's other Big Four competitors: Syngenta (NYSE: SYT ) , DuPont (NYSE: DD ) , and Dow Chemical (NYSE: DOW ) .
Meanwhile, super weeds that are resistant to treatments from any of these four companies are also developing. In 2012, US News & World reported that "after years of constant exposure, certain invasive plants have also developed a resistance [to Monsanto's Roundup herbicide], leading farmers to use more of the chemical. In some cases, the weeds have grown completely tolerant to the chemical, giving farmers fits."
Using earlier data, The New York Times demonstrated the proliferation of superweeds. In 2000, only one state (California) had one type of weed that was resistant to glyphosate, a popular herbicide. By 2009, there were 22 states dealing with such problems -- often on a much bigger scale.
Giving a tour on his organic, sustainable coffee farm in Atenas, Costa Rica, Gabriel Calderon picks a leaf from a coffee plant that is infected with the potentially dangerous form of the rust fungus.
"Every year, we lose a small portion of our coffee to this fungus. Most years, other farmers don't have it, but this year, over 15% of this country's coffee will be lost to the fungus. Why hasn't our farm experienced such devastation?" Calderon asks.
The answer is that his farm, which has been extensively studied by local scientists, has more than 700 different types of life forms on it, while a conventional coffee farm may have less than 100. In the case of the rust fungus, there is enough biodiversity on Calderon's farm to keep the threat in check. On other farms, where no such diversity exists, the use of chemicals has wiped them out.
Though the crop and pests differ greatly, the same story plays out in North America year after year.
While this only tangentially refers back to GMOs, there's an important connection. The way that farming is increasingly practiced now -- where one or two crops are grown on huge swaths of land -- biological diversity is sacrificed for short-term profits.
This is all fine and good until a new bug or weed comes along (see above) that is resistant to customary treatments. Then, because of a lack of diversity, that new threat can wipe out a whole year's harvest. While GMOs per se aren't to blame for this phenomenon, they help encourage and proliferate such practices.
The great unknowns
But perhaps the greatest threat -- that which strikes the most fear in Americans -- is the one we don't yet know about. Genetically modified crops have been around on a large scale for only about two decades.
In that time, no obvious and alarming health threats have been observed by reputable sources. In 2008, the National Center for Biotechnology Information analyzed nutritional differences between conventional and GM wheat, corn, and tomatoes. The study found that the GM plants were "nutritionally similar to conventional varieties of wheat, corn, and tomato on the market."
But it's still too early to know for sure that there aren't any long-term consequences to eating GMOs. Several opponents focus specifically on the possibility of GMOs acting as dangerous endocrine disruptors. More studies need to be carried out before the veracity of such claims can be verified.
Approach with eyes wide open
In the end, if you're investing in this sector, you need to keep a sharp eye on both scientific findings within this arena as well as possible legislation resulting from a large public outcry.
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