¿Transgénicos o ciencia?

ALAI AMLATINA, 17/09/2015.- Jonathan Latham es biólogo, botánico, tiene maestría en genética vegetal y doctorado en virología. Publicó recientemente un texto titulado “Growing Doubt: a Scientist’s Experience of GMOs” (Dudas crecientes: la experiencia de un científico con los organismos modificados genéticamente), donde expresa graves preocupaciones sobre los impactos de los transgénicos y de las nuevas técnicas de modificación genética. Se basa para ello en su experiencia como científico que desde la década de 1990 trabajó haciendo plantas transgénicas, como parte de sus actividades académicas.

Como joven científico, Latham no estaba preocupado por los impactos en salud o ambiente de estas plantas creadas en laboratorio, en parte porque su entusiasmo por la ciencia y la investigación opacaban otros aspectos, en parte porque no imaginaba entonces que con la fragilidad y nivel de incertidumbres de tales técnicas, estas llegarían a productos de consumo y al ambiente.

Pero a las empresas de transgénicos –y los científicos que lucran gracias a ellas– eso no les importó y ahora varios cultivos y muchos alimentos con transgénicos se colaron a nuestros campos y mesas, pese a que tengan efectos dañinos.

Después de haber analizado cuidadosamente numerosas evaluaciones de riesgo de cultivos transgénicos, Latham señala varios problemas. Uno de ellos es que son las empresas que hacen su propia evaluación de riesgo –las agencias gubernamentales solamente las revisan, en general superficialmente. Las empresas, pese a que los datos de sus análisis muestren daños o aunque los análisis sean intencionalmente de pésima calidad, invariablemente informan que sus productos no tienen ningún problema.

Hay varios casos –por ejemplo el maíz Mon863 de Monsanto– en el que científicos independientes accedieron al estudio completo de la empresa, comprobando que las conclusiones no eran coherentes con el propio estudio, sino que habían sido maquilladas para desestimar los daños. Las agencias de bioseguridad y de inocuidad alimentaria solamente leyeron las conclusiones y dieron por buenas las recomendaciones de Monsanto. Eso hizo también la Comisión Federal para la Protección contra Riesgos Sanitarios (Cofepris) en México y organismos similares en varios otros países de América Latina, aunque el estudio en sí muestra graves anomalías en órganos internos de ratas de laboratorio.

Otro ejemplo que expone Latham es que la bacteria Bacillus Thuringiensis, (usada para hacer cultivos transgénicos insecticidas llamados “Bt”) es virtualmente igual al Bacillus Anthrax origen del conocido tóxico Ántrax; y que la acción de cultivos insecticidas Bt tienen similitudes estructurales con la del ricino. Ricino y ántrax se han usado como potentes tóxicos contra humanos. Además, agrega, no se conoce el modo de acción de las proteínas Bt, lo cual imposibilita análisis serios de sus riesgos a la salud, más grave aún porque las proteínas Cry (las del Bt) han mostrado ser tóxicas para células humanas in vitro.

El aumento de agrotóxicos que conllevan los transgénicos es un enorme problema para la salud y el ambiente. El glifosato, el agrotóxico más usado con transgénicos, fue declarado cancerígeno por la Organización Mundial de la Salud. Latham explica que otro químico que se usa con los cultivos transgénicos, el glufosinato, tiene un mecanismo de acción (inhibidor de la enzima glutamina sintetasa) que es tóxico para hierbas y también muchos organismos como hongos, bacterias y animales. Pero además, es neurotóxico en mamíferos y no se degrada fácilmente en el ambiente. Con los transgénicos manipulados para tolerar glufosinato, éste permanece en los cultivos, lo ingerimos en alimentos y se puede detectar que sigue presente hasta meses después. Su acción es tan amplia, dice Latham, que llamarlo “herbicida” es apenas un nombre que no refleja la amplitud de impactos que conlleva sobre muchas otras especies.

Latham y Allison Wilson, otra científica, revelaron que una secuencia viral usada como promotor en casi todos los cultivos transgénicos (CaMV, virus del mosaico de la coliflor); se asumió erróneamente como “segura” por 20 años, pero un estudio comisionado en 2013 por EFSA (autoridad europea de seguridad alimentaria) mostró que es capaz de alterar la expresión normal de muchos otros genes en plantas, dejándolas indefensas ante las enfermedades, entre otros problemas. La EFSA trató de ignorar el estudio, pero Latham y Wilson lo sacaron a la luz.

El texto no sólo coloca a debate problemas graves de los transgénicos, expone también que si éstos llegaron a los mercados y alimentación, es solamente por presión comercial de las trasnacionales de transgénicos y la falta de ética de los científicos involucrados, ya que no hay certidumbre de su inocuidad y por el contrario, existe certidumbre de un amplio espectro de riesgos. Son los mismos actores que “informan” a los gobiernos -y a jueces en casos de litigio– a favor de los transgénicos, ocultando los problemas reales.

Justamente, ante esta falta de ética científica, ante estos intentos de simplificación absurda de la complejidad de la naturaleza y ante el descompromiso con las necesidades, culturas e historia de la mayoría, se han ido formando en el mundo asociaciones de científicos críticos que no aceptan seguir siendo cómplices de la ciencia mercenaria que trabaja para los intereses de lucro empresariales.  Ejemplo de ellos es la recientemente formada Unión de Científicos Comprometidos con la Sociedad y la Naturaleza en América Latina (UCCSNAL), que se constituyó en una reunión en Rosario, Argentina, con científicos y expertos de diez países del continente. La UCCSNAL se posicionó por la prohibición de los transgénicos, haciendo suyas en su declaración constitutiva las palabras del difunto Dr. Andrés Carrasco (nombrado presidente honorario): “Los transgénicos son una tecnología basada en supuestos falaces y anacrónicos que reducen y simplifican la lógica científica, al punto de ya no ser válida”.

El emperador transgénico está desnudo y cada vez más científicos responsables lo están denunciando.

– Silvia Ribeiro es investigadora del Grupo ETC. www.etcgroup.org

Growing Doubt: a Scientist’s Experience of GMOs

August 31, 2015 Biotechnology, Commentaries, Health 32 Comments

Jonathan R. Latham, PhD

By training, I am a plant biologist. In the early 1990s I was busy making genetically modified plants (often called GMOs for Genetically Modified Organisms) as part of the research that led to my PhD. Into these plants we were putting DNA from various foreign organisms, such as viruses and bacteria.

I was not, at the outset, concerned about the possible effects of GM plants on human health or the environment. One reason for this lack of concern was that I was still a very young scientist, feeling my way in the complex world of biology and of scientific research. Another reason was that we hardly imagined that GMOs like ours would be grown or eaten. So far as I was concerned, all GMOs were for research purposes only.

Gradually, however, it became clear that certain companies thought differently. Some of my older colleagues shared their skepticism with me that commercial interests were running far ahead of scientific knowledge. I listened carefully and I didn’t disagree. Today, over twenty years later, GMO crops, especially soybeans, corn, papaya, canola and cotton, are commercially grown in numerous parts of the world.

Jonathan Latham

Jonathan Latham

Depending on which country you live in, GMOs may be unlabeled and therefore unknowingly abundant in your diet. Processed foods (e.g. chips, breakfast cereals, sodas) are likely to contain ingredients from GMO crops, because they are often made from corn or soy. Most agricultural crops, however, are still non-GMO, including rice, wheat, barley, oats, tomatoes, grapes and beans.

For meat eaters the nature of GMO consumption is different. There are no GMO animals used in farming (although GM salmon has been pending FDA approval since 1993); however, animal feed, especially in factory farms or for fish farming, is likely to be GMO corn and GMO soybeans. In which case the labeling issue, and potential for impacts on your health, are complicated.

I now believe, as a much more experienced scientist, that GMO crops still run far ahead of our understanding of their risks. In broad outline, the reasons for this belief are quite simple. I have become much more appreciative of the complexity of biological organisms and their capacity for benefits and harms. As a scientist I have become much more humble about the capacity of science to do more than scratch the surface in its understanding of the deep complexity and diversity of the natural world. To paraphrase a cliché, I more and more appreciate that as scientists we understand less and less.

The Flawed Processes of GMO Risk Assessment

Some of my concerns with GMOs are “just” practical ones. I have read numerous GMO risk assessment applications. These are the documents that governments rely on to ‘prove’ their safety. Though these documents are quite long and quite complex, their length is misleading in that they primarily ask (and answer) trivial questions. Furthermore, the experiments described within them are often very inadequate and sloppily executed. Scientific controls are often missing, procedures and reagents are badly described, and the results are often ambiguous or uninterpretable. I do not believe that this ambiguity and apparent incompetence is accidental. It is common, for example, for multinational corporations, whose labs have the latest equipment, to use outdated methodologies. When the results show what the applicants want, nothing is said. But when the results are inconvenient, and raise red flags, they blame the limitations of the antiquated method. This bulletproof logic, in which applicants claim safety no matter what the data shows, or how badly the experiment was performed, is routine in formal GMO risk assessment.

To any honest observer, reading these applications is bound to raise profound and disturbing questions: about the trustworthiness of the applicants and equally of the regulators. They are impossible to reconcile with a functional regulatory system capable of protecting the public.

The Dangers of GMOs

Aside from grave doubts about the quality and integrity of risk assessments, I also have specific science-based concerns over GMOs. I emphasise the ones below because they are important but are not on the lists that GMO critics often make.

Many GMO plants are engineered to contain their own insecticides. These GMOs, which include maize, cotton and soybeans, are called Bt plants. Bt plants get their name because they incorporate a transgene that makes a protein-based toxin (usually called the Cry toxin) from the bacterium Bacillus thuringiensis. Many Bt crops are “stacked,” meaning they contain a multiplicity of these Cry toxins. Their makers believe each of these Bt toxins is insect-specific and safe. However, there are multiple reasons to doubt both safety and specificity. One concern is that Bacillus thuringiensis is all but indistinguishable from the well known anthrax bacterium (Bacillus anthracis) (1). Another reason is that Bt insecticides share structural similarities with ricin. Ricin is a famously dangerous plant toxin, a tiny amount of which was used to assassinate the Bulgarian writer and defector Georgi Markov in 1978. A third reason for concern is that the mode of action of Bt proteins is not understood (Vachon et al 2012); yet, it is axiomatic in science that effective risk assessment requires a clear understanding of the mechanism of action of any GMO transgene. This is so that appropriate experiments can be devised to affirm or refute safety. These red flags are doubly troubling because some Cry proteins are known to be toxic towards isolated human cells (Mizuki et al., 1999). Yet we put them in our food crops.

A second concern follows from GMOs being often resistant to herbicides. This resistance is an invitation to farmers to spray large quantities of herbicides, and many do. As research recently showed, commercial soybeans routinely contain quantities of the herbicide Roundup (glyphosate) that its maker, Monsanto, once described as “extreme” (Bøhn et al 2014).

Glyphosate has been in the news recently because the World Health Organisation no longer considers it a relatively harmless chemical, but there are other herbicides applied to GMOs which are easily of equal concern. The herbicide Glufosinate (phosphinothricin, made by Bayer) kills plants because it inhibits the important plant enzyme glutamine synthetase. This enzyme is ubiquitous, however, it is found also in fungi, bacteria and animals. Consequently, Glufosinate is toxic to most organisms. Glufosinate is also a neurotoxin of mammals that doesn’t easily break down in the environment (Lantz et al. 2014). Glufosinate is thus a “herbicide” in name only.

Thus, even in conventional agriculture, the use of glufosinate is hazardous; but With GMO plants the situation is worse yet. With GMOs, glufosinate is sprayed on to the crop but its degradation in the plant is blocked by the transgene, which chemically modifies it slightly. This is why the GMO plant is resistant to it; but the other consequence is that when you eat Bayers’ Glufosinate-resistant GMO maize or canola, even weeks or months later, glufosinate, though slightly modified, is probably still there (Droge et al., 1992). Nevertheless, though the health hazard of glufosinate is much greater with GMOs, the implications of this science have been ignored in GMO risk assessments of Glufosinate-tolerant GMO crops.

A yet further reason to be concerned about GMOs is that most of them contain a viral sequence called the cauliflower mosaic virus (CaMV) promoter (or they contain the similar figwort mosaic virus (FMV) promoter). Two years ago, the GMO safety agency of the European Union (EFSA) discovered that both the CaMV promoter and the FMV promoter had wrongly been assumed by them (for almost 20 years) not to encode any proteins. In fact, the two promoters encode a large part of a small multifunctional viral protein that misdirects all normal gene expression and that also turns off a key plant defence against pathogens. EFSA tried to bury their discovery. Unfortunately for them, we spotted their findings in an obscure scientific journal. This revelation forced EFSA and other regulators to explain why they had overlooked the probability that consumers were eating an untested viral protein.

This list of significant scientific concerns about GMOs is by no means exhaustive. For example, there are novel GMOs coming on the market, such as those using double stranded RNAs (dsRNAs), that have the potential for even greater risks (Latham and Wilson 2015).

The True Purpose of GMOs

Science is not the only grounds on which GMOs should be judged. The commercial purpose of GMOs is not to feed the world or improve farming. Rather, they exist to gain intellectual property (i.e. patent rights) over seeds and plant breeding and to drive agriculture in directions that benefit agribusiness. This drive is occurring at the expense of farmers, consumers and the natural world. US Farmers, for example, have seen seed costs nearly quadruple and seed choices greatly narrow since the introduction of GMOs. The fight over GMOs is not of narrow importance. It affects us all.

Nevertheless, specific scientific concerns are crucial to the debate. I left science in large part because it seemed impossible to do research while also providing the unvarnished public scepticism that I believed the public, as ultimate funder and risk-taker of that science, was entitled to.

Criticism of science and technology remains very difficult. Even though many academics benefit from tenure and a large salary, the sceptical process in much of science is largely lacking. This is why risk assessment of GMOs has been short-circuited and public concerns about them are growing. Until the damaged scientific ethos is rectified, both scientists and the public are correct to doubt that GMOs should ever have been let out of any lab.

(An earlier version of this article appeared at http://nutritionstudies.org/)

(1) Two references on the anthrax issue (added Sept 2nd): Helgason, E., O. A. Økstad, D. A. Caugant, H. A. Johansen, A. Fouet, M. Mock, I. Hegna, and A.-B. Kolstø. 2000. Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis—one species on the basis of genetic evidence. Appl. Environ. Microbiol. 66: 2627-2630.

And:

Adelaida M. Gaviria Rivera, Per Einar Granum, Fergus G. Priest. 2000. Common occurrence of enterotoxin genes and enterotoxicity in Bacillus thuringiensis. FEMS Microbiology Letters 190 (2000) 151-155; http://dx.doi.org/10.1111/j.1574-6968.2000.tb09278.x

References

Bøhn, T, Cuhra, M, Traavik, T, Sanden, M, Fagan, J and Primicerio, R (2014) Compositional differences in soybeans on the market: Glyphosate accumulates in Roundup Ready GM soybeans. Food Chemistry 153: 207-215.
Droge W, Broer I, and Puhler A. (1992) Transgenic plants containing the phosphinothricin-N-acetyltransferase gene metabolize the herbicide L-phosphinothricin (glufosinate) differently from untransformed plants. Planta 187: 142-151.
Lantz S et al., (2014) Glufosinate binds N-methyl-D-aspartate receptors and increases neuronal network activity in vitro. Neurotoxicology 45: 38-47.
Latham JR and Wilson AK (2015) Off -­ target Effects of Plant Transgenic RNAi: Three Mechanisms Lead to Distinct Toxicological and Environmental Hazards.
Mizuki, E, Et Al., (1999) Unique activity associated with non-insecticidal Bacillus thuringiensis parasporal inclusions: in vitro cell- killing action on human cancer cells. J. Appl. Microbiol. 86: 477–486.
Vachon V, Laprade R, Schwartz JL (2012) Current models of the mode of action of Bacillus thuringiensis insecticidal crystal proteins: a critical review. Journal of Invertebrate Pathology 111: 1–12.

 

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