10 conceptos erróneos sobre los transgénicos

Desde que los científicos comenzaron a probar cultivos modificados genéticamente a fines de la década de 1980, la idea de jugar con el ADN en nuestro suministro de alimentos ha sido uno de los temas más controvertidos que puedas imaginar. Para algunos, los OGM ( organismos genéticamente modificados , que incluyen tanto plantas como animales) son un gran avance científico, que nos proporcionará mayores rendimientos de cultivos y alimentos más nutritivos, y ayudará a las granjas en los países en desarrollo a producir lo suficiente como para acabar con el hambre. Para otros, los transgénicos son "Frankenfood", un ejemplo de pesadilla de la ciencia enloquecida, que plantea graves riesgos potenciales tanto para la salud humana como para el medio ambiente.

La aguda división sobre los transgénicos no es solo ideológica, sino también internacional. En los EE. UU., la Administración de Drogas y Alimentos (FDA) decidió en 1992 que los OGM no eran inherentemente peligrosos y no requerían una regulación especial [fuente: American Radio Works ]. Hoy en día, alrededor del 60 al 70 por ciento de los alimentos procesados ​​de EE. UU. tienen ingredientes derivados de OMG [fuente: Dupont ]. Por el contrario, en Europa, la Unión Europea impuso regulaciones mucho más estrictas. Solo alrededor del 1 por ciento de las tierras de cultivo tienen cultivos transgénicos y muy pocos alimentos procesados ​​los contienen [fuente: Barber ].

Los defensores de los OGM apuntan a la aprobación de organizaciones científicas independientes como el Consejo Nacional de Investigación, que concluyó en 2010 que los OGM en realidad tienen menos efectos adversos sobre el medio ambiente que los cultivos ordinarios cultivados con pesticidas, y la Organización Mundial de la Salud, cuyo sitio web afirma que los estudios sobre los alimentos modificados genéticamente muestran que "no es probable que presenten riesgos para la salud humana" [fuentes: NAP , OMS ]. Los críticos afirman que la investigación sobre la seguridad de los OMG es insuficiente porque tiende a centrarse en los efectos a corto plazo en lugar de a largo plazo, que advierten que son desconocidos [fuente: Barber ].

Como suele ocurrir con las controversias científicas, la verdad es demasiado compleja y necesita demasiadas calificaciones para caber en una calcomanía. Aquí hay un vistazo a 10 afirmaciones sobre los OGM que los debatientes pronuncian con frecuencia, y la verdad real detrás de ellas.

1. La modificación genética de los alimentos es nueva
2. Los transgénicos son solo una versión moderna de la reproducción selectiva
3. Hay pruebas sólidas de que los alimentos transgénicos causan cáncer
4. Los cultivos transgénicos son peligrosos ya que contienen sustancias tóxicas
5. Los cultivos transgénicos representan un riesgo para la salud de las personas con alergias
6. Los genes alterados de las plantas transgénicas invariablemente se propagarán y causarán estragos
7. Si semillas transgénicas patentadas crecen accidentalmente en su propiedad, podría ser demandado
8. Los cultivos transgénicos causan una disminución catastrófica de las abejas melíferas
9. Casi todos los cultivos de hoy son transgénicos
10. Los transgénicos no están etiquetados y son imposibles de evitar

Realmente no. Los críticos de los transgénicos a menudo describen los ajustes genéticos como una ruptura antinatural con la herencia pastoril de la agricultura. Pero, en verdad, hemos estado jugando con el ADN de nuestros alimentos desde los albores de la agricultura, mediante la cría selectiva de plantas y animales con rasgos deseables [fuente: Scientific American ].

Esas mazorcas de maíz de color amarillo dorado y granos regordetes que nos encanta untar con mantequilla no existían hace 10.000 años. En cambio, los humanos antiguos tomaron una hierba salvaje y desaliñada llamada teosinte , que tiene mazorcas y granos comparativamente pequeños, y cruzaron los especímenes más robustos. Los genetistas modernos que han analizado el ADN del maíz moderno y sus ancestros antiguos descubrieron que solo se necesitaba una pequeña alteración en el genoma (alrededor de cinco regiones de genes individuales o grupos de genes) para cambiar el teosinte en las primeras variedades de maíz (otra palabra para maíz). Pero los cambios menores en los genes influyentes pueden marcar una gran diferencia. En genética, este tipo de intervención humana en la evolución se denomina selección artificial [fuente:Universidad de Utah ]. La selección artificial a lo largo de los siglos ha aumentado el rendimiento de los cultivos y ha creado alimentos que son más grandes, más resistentes a las plagas y enfermedades, y más sabrosos [fuente: Museo Americano de Historia Natural ].

Bueno, sí y no. Es cierto que la reproducción tradicional, el cultivo de plantas a propósito o el cruce de ciertas características, puede ser un asunto complicado. Dado que las plantas a menudo intercambian grandes porciones no reguladas de sus genomas, los criadores pueden terminar obteniendo rasgos no deseados junto con los que están buscando. Por ejemplo, las variedades de patata creadas a través del cultivo convencional a veces producen niveles excesivos de sustancias químicas llamadas glicoalcaloides , que pueden ser venenosas. Y puede tomar muchas generaciones obtener las características que los criadores están tratando de lograr [fuente: Universidad de California en San Diego ].

La ingeniería genética es un poco más sistemática. Básicamente, los científicos extraen el ADN de un organismo, copian el gen responsable de las características deseadas (llamado transgén ) y luego lo colocan en otro organismo. Lo hacen insertándolo en una bacteria e infectando el organismo con él, o usando una pistola genética, que dispara partículas de oro microscópicas cubiertas con copias del transgén en el organismo. Dado que no pueden controlar si el transgén se inserta en el genoma del receptor, pueden ser necesarios cientos de intentos para obtener algunos OMG [fuente: Universidad de Nebraska -Lincoln ].

But there is one really significant difference. Genetic engineering can produce much more radical changes in plants and animals than selective breeding ever could. Scientists, for example, have implanted monkey embryos with a jellyfish gene to breed monkeys with glowing green feet [source: Coghlan]. It's not hard to imagine how the power to create a plant or animal with freaky characteristics could be misused, either accidentally or on purpose.

Not exactly. A 2012 French study found that rats fed a lifetime diet of genetically modified corn that made it resistant to the herbicide Roundup— or else given water containing Roundup — suffered tumors and organ damage. The researchers reported that 50 percent of male rats and 70 percent of females died prematurely, compared with only 30 percent of males and 20 percent of females in a control group [source: Reuters].

That made for a scary-sounding headline. But as routinely happens in the world of science, other researchers who had come to different conclusions in their own work started scrutinizing the study. Six French scientific academies quickly issued a rebuttal in which they found fault with the design of the experiment, the statistical analysis and the amount of data. The European Food Safety Authority declared that the study was "of insufficient scientific quality to be considered as valid for risk assessment." Additionally, the strain of rat that the researchers picked tends to get breast tumors easily, and can get them from overeating or eating corn contaminated by a common fungus that causes a hormone imbalance. The study didn't screen for those factors, so it's unclear whether the rats' tumors were caused by the GMO corn [source: MacKenzie].

Some GMOs — for example, a variety called Bt corn — actually do contain a pest-killing toxin. That may sound pretty dangerous, until you stop to consider that unlike, say, chemical insecticides and herbicides, the toxin in the Bt corn is engineered to work on specific ravenous insects, and doesn't affect other species, including humans.

A recent Scientific American article that summarized the research on Bt corn noted, "The evidence overwhelmingly demonstrates that Bt toxins are some of the safest and most selective insecticides ever used. Claims that Bt crops poison people are simply not true." Indeed, the article argues that when properly managed, fields of Bt corn actually help protect the environment, because they reduce the use of broad-spectrum insecticides that kill off insects, including beneficial ones, indiscriminately [source: Jabr].

Even so, there are downsides. One problem is that pests can become resistant to genetically engineered toxins, just as they can develop immunity to pesticides. For example, farmers in the Midwest have discovered that one variety of Bt corn no longer repels the root-chomping beetle larvae that it's meant to stop. If GMOs fail to be pest resistant , that might lead farmers to start dousing their fields with problematic chemicals again [source: Jabr].

This was one of the first big fears that people had about GMOs. If you know that you're deathly allergic to peanuts, you'll probably stay away from peanut butter . But if a scientist puts peanut genes into some other food, would you have to avoid it as well, and how would you know they were even there?

There actually is an example of this happening. Back in the mid-1990s, scientists found that a Brazil nut protein, added to improve the nutritional quality of genetically engineered soybeans, had the ability to cause an allergic reaction in people sensitive to Brazil nuts [source: Nordlee et al.].

Unwary consumers never actually got sick from eating those soybeans . That's because the researchers discovered the dangerous effect during the development process and ultimately abandoned that particular GMO [source: Palmer].The allergy risk could be nipped in the bud by such safety testing, which is why the American Medical Association, among others, has called for mandatory pre-market safety testing of GMOs [source: Eng].

The FDA doesn't require allergy screening, but instead uses a "voluntary consultation process" to look at safety. And while the agency hasn't found any GMOs that cause allergy problems so far, it's possible that some might slip through the regulatory cracks. The answer might be for Congress to mandate such testing and provide funds for it, but don't hold your breath waiting for that to happen.

It's possible to conjure up all sorts of terrifying scenarios. What if a GMO gene that causes resistance to antibiotics somehow is transferred from a food into pathogenic bacteria in your gastrointestinal tract? That could make you really, really sick [sources: WHO, Palmer]. But it's probably not going to happen. Dutch scientists, who looked at the risks of specific bacteria being altered by GMO genes in a 2005 study, found that the data "does not give rise to health concerns" [source: Kleter et al.]. And an Australian government scientist concluded in a 2008 study that the frequency of such gene transfers from plant-based foods to microorganisms is so low that it "poses negligible risks to human health or the environment [source: Keese]. Nevertheless, the World Health Organization (WHO) doesn't want to take any chances, and is urging member countries to pick GMOs that don't have antibiotic resistance.

Another potential problem is outcrossing, in which genes from GM plants spread into conventional crops or wild species. Traces of a type of corn only approved for animal use, for example, once began to show up in corn products for human consumption. Some countries have adopted regulations to reduce mixing, including a clear separation between fields with GM and conventional crops [source: WHO]. And a 2006 Australian government report noted that outcrossing could be controlled by making GMO plants' pollen sterile [source: Mills].

Like many of the fears about GMOs, this is one that has a germ of truth in it. In 1999, agribusiness giant Monsanto sued a Canadian organic canola farmer, Percy Schmeiser, for growing the company's pesticide-tolerant canola without paying the required fees. The farmer, in his defense, argued that he hadn't planted any of the company's GMO canola seeds, and that they must have blown onto his property.

What actually happened is still in dispute. But ultimately, the Canadian Supreme Court ruled that although 95 percent of the canola plants on Schmeiser's farm had grown from Monsanto seeds, he didn't owe the Monsanto any royalties because he did not benefit from them. The company ended up paying him $660, the amount Schmeiser spent to remove the plants [source: Hartley]. On its Web site, Monsanto says that it only pursues legal action against farmers who've purchased patented GMO seeds and then violated the terms of use that bar them from saving and replanting seeds produced by the plants.

An NPR journalist who investigated the issue of windblown seeds in 2012, reported that he didn't find any cases where Monsanto had sued anyone over trace amounts of seeds introduced through cross-pollination [source: Charles].

This seems to be a case of guilt by association. Between 2008 and 2013, 30 percent of bees in the U.S. have either disappeared or failed to pollinate blossoms in the spring. It's even worse in some other countries — Spain has lost close to 80 percent of its beehives [source: Entine]. Some beekeepers and environmental activists have argued that the cause is a powerful class of pesticides called neonicontinoids, which are similar in structure and action to nicotine. Unlike the usual pesticide sprays, neonicontinoids are absorbed by plants and relocated through their vascular systems, so that boring insects will suck them up [sources: Wines, Oliver].

These pesticides are different from GMOs, though activists sometimes lump them together, possibly because the pesticides are sometimes used to treat seeds. There's no solid evidence that GMOs themselves are causing the bee collapse. That said, GMOs may not necessarily be so great for other insects. There are recent studies that indicate that in rare instances, they may inadvertently kill butterflies, ladybugs and other harmless or even beneficial insects [source: Jabr].

It is true that since GMOs were introduced in the 1980s, people in the U.S. have consumed a lot more of them. By one estimate, 70 percent of processed foods in the U.S. contain genetically modified ingredients [source: Scientific American].

But that's largely because a few big-ticket crops — corn, in particular— are used in a lot of foods. According to one anti-GMO Web site, there are around 60 GMOs that have been approved in the U.S. for human consumption or animal feed. That list includes 20 varieties of corn, 11 varieties of oilseed rape/canola, 11 varieties of cotton, six tomato varieties, three types of soybeans and sugar beets, two different squash varieties, and single types of cantaloupe, rice, flax, radicchio, papaya, alfalfa and wheat [source: Organic Consumers].

But of all those crops, only corn, soybeans, cotton, canola, squash, and papaya grown in Hawaii currently are being commercially cultivated. Some were tried but eventually taken off the market, while others — like wheat and rice—have never been grown in the U.S. [source: Organic Consumers]. The upshot is that most of the vegetables and fruits in your local supermarket are non-GMOs.

One big reason GMOs haven't caught on even more extensively is that U.S. consumers are suspicious of them. According to a June 2013 ABC News poll, 52 percent of Americans believe such foods are unsafe [source: Langer].

It is true that the federal government doesn't require food from animals that have been raised on feed from GMO plants to be labeled. However, in June 2013, the U.S. Department of Agriculture officially approved a label that food companies can use to identify meat and liquid egg products that come from animals that haven't been fed GMOs. All these producers have to do is provide proof that they've been vetted by an independent certifying organization [source: Strom].

Additionally, some specialty grocery store chains are trying to keep their distance from GMOs. Trader Joe's, for example, recommends that consumers concerned about genetic engineering buy its organic-labeled meats and dairy products and wild-caught seafood. Another chain, Whole Foods, announced that by 2018 all products in its U.S. and Canadian stores will be labeled to indicate whether or not they contain GMO ingredients, and it will label some animal products as non-GMO verified.

But unless you grow your own food, perhaps the surest way to avoid GMOs is to live in Europe. Since the late 1990s, the European Union has required labeling of food products containing GMOs, and as a result, European food retailers — fearful that the labels would drive away customers — have kept them out of their wares. As a recent Scientific American editorial notes, "It is virtually impossible to find GMOs in European supermarkets."

Author's Note: 10 Misconceptions About GMOs

No estaba particularmente bien versado en la controversia sobre los OGM antes de investigar este artículo, aunque como muchas personas, probablemente albergaba una vaga inquietud sobre los llamados "Frankenfoods". Sin embargo, después de aprender más sobre el tema, he desarrollado una visión más matizada. No es fácil descartar todas las preocupaciones que tienen las personas que se oponen a los OGM, y tiene sentido para mí que los consumidores puedan decidir si quieren consumir alimentos OGM o evitarlos. Pero también creo que se puede argumentar con fuerza que los transgénicos en realidad pueden ser buenos para las personas, particularmente en los países en desarrollo donde la desnutrición sigue siendo un problema grave. Por ejemplo, un OGM, Golden Rice, que ha sido diseñado para producir betacaroteno, un precursor de la vitamina A, podría desempeñar un papel importante en la lucha contra la deficiencia de vitamina A, que mata a 250,

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