Exploring the sense and nonsense of food and health

A Conundrum: GMOs and Labeling

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By Sally J. Feltner, PhD, RDN

In light of the current battle over GMO labeling of foods and the government interference in attempts to stop labeling these foods, one wonders if all consumers know what we are talking about. Most surveys in the past few years tell us we know surprisingly little. In one survey only 26% of consumers believe that have eaten genetically modified foods and 60 percent believe they have never eaten these foods. Yet, 92% want these foods labeled. For a more complete discussion, click my previous post HERE.

Here is the basic problem. Many groups want these foods labeled and do not trust that enough independent research has been done to “prove” they are safe for humans. Many also claim that they are detrimental to the environment. On the other hand, big companies like Monsanto, involved in producing the genetically altered seeds, claim that there has never been a reported danger to human health or the environment.

It is incredibly unlikely that someone has never eaten genetically modified foods. In 2004, 85 percent of soybeans and 45 percent of corn grown in the U.S. were genetically modified. It is very likely that these numbers have only grown since then.

Is genetic modification really new? This is a frequent argument from those who promote GMO foods. Actually, it is and it is not – it just depends on the differences in the processes. Humans have been modifying plants and animals for about 10,000 years. Our present day pumpkins, potatoes, corn, oats and rice have developed with human intervention, for example.

Plant breeders use a process called hybridization in which two related plants are cross-pollinated or cross-fertilized. The breeder would then select the offspring that acquired the desired traits from each plant. The same results occur with cross-breeding of the same species of animals. This process has limitations of time and outcome. A new trait can only be produced in once reproductive cycle and not every offspring will inherit the desirable traits.

On the other hand, modern biotechnology selects genes in a laboratory that speeds up this process in that it allows breeders to select, modify and transfer single genes. Genes can be selected from any species and transferred to other organisms, not necessarily related by species. This allows traits from different species and completely different organisms to be used. So we can insert genes from bacteria and put it into a plant DNA, for example. This is generally referred to as recombinant (rDNA). Organisms so altered are called “transgenic” or “a genetically modified organism” (GMO). Plants or animals bred by conventional methods are genetically modified relative to their wild ancestors, but are not considered transgenic. They would not normally carry genes from an unrelated species.

Bacillus thuringenesis: A bacterial Insecticide.

An example of gene transfer from one organism to another) is Bt (Bacillus thuringenesis,) a bacteria that carries a gene that produces a insecticide long used by organic gardeners. This process allows the plant  to make its own insecticide from the bacterial gene. The molecules are toxic to many insects and have been engineered into corn, soybeans, and cottonseed oil. Bt corn is designed to control corn pests such as the European corn borer, corn earworm, and southwestern corn borer, and Bt cotton effectively controls cotton pests such as the tobacco budworm, cotton bollworm, and pink bollworm The use of Bt crops has led to a reduction in conventional synthetic insecticide use. The EPA has analyzed Bt crops and found that they do not pose any significant risks to human health. Specifically, the EPA has done studies showing that the Bt protein in GM plants behaves as would be expected for a dietary protein, is not structurally related to a known food allergen or protein toxin, and does not show toxicity when administered orally at high doses.

Roundup Ready Soybeans

More recent attention and concern has been centered around the herbicide Roundup.  GM herbicide-tolerant crops enable farmers to use certain herbicides that will kill weeds without harming their crop. An ingredient in Roundup is glyphosate that is the most widely used herbicide in the world by volume. It is employed extensively in agriculture and can be found in garden products in many countries. The resistance was also engineered into not only soybeans, but corn, cotton, sugar beets, rapeseed (canola) and wheat.

The use of these herbicide-tolerant crops has allowed farmers to switch from traditional herbicides to glyphosate. The good news is that glyphosphate is thought to be less toxic and less persistent than traditional herbicides, which means that it carries fewer health risks for humans.

However, the World Health Organization recently announced that glyphosate is a probable carcinogen to humans, so we still need to be concerned.  Although studies have shown conflicting conclusions about the link between glyphosate and cancer in humans, glyphosate has been linked to cancer in rats and mice and experiments in human cells have shown that exposure to glyphosate can cause DNA damage.

Plants may develop resistance to herbicides over time. Weeds that have developed resistance to herbicides such as glyphosate may require higher amounts of glyphosate and perhaps other herbicides to keep them in check, and this means that herbicide-tolerant crops will be exposed to higher levels of herbicides as well.

GMOs have played a mixed role in helping reduce pesticide use in some cases (e.g. with Bt crops) and with increased pesticide use in other cases (e.g. with herbicide-resistant weeds). Thus, their use has not resolved our pesticide problem. Encouragingly, research is ongoing to find synthetic pesticides that have high specificity for their target pests. Alternative, non-chemical forms of pest control that are less toxic to humans and other organisms are also being studied.

However, the debate continues – should GMO’s be labeled?

FYI: Roundup (glyphosate) was commercially introduced and marketed by Monsanto in 1974. This popular weed killer now faces a lawsuit over cancer claims.


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