Genetic Changes. Allergenicity

Although some bioengineers claim that GMOs are no different from plants and animals derived from traditional breeding, genetic engineering is revolutionary and provides unprecedented power to alter and accelerate evolution. GMOs are radically different from anything produced before. Unanticipated incidents signal how unprepared science and society may be for unanticipated consequences of widespread utilization of this technology in food production.

The DNA insertion sequences from viruses and bacteria that allow these pathogens to infect their host organisms also permit movement of transgenes to new positions within an organism's genome. GM soybeans exemplify how this instability of transgenes can lead to new mutations. Roundup Ready brand soybeans were engineered to survive applications of the herbicide glyphosate.

The molecular marker that tracks the Roundup- resistant transgene has detected a new molecular signature in Roundup Ready seed now on the market that is distinctly different from the approved transgenic event. This confirms that a genetic change has occurred and illustrates the inherent genomic instability of GM products. In addition to movement within genomes, transgenes may move from the host organism into the DNA of other organisms, a phenomenon referred as "horizontal gene transfer."

For example, a synthetic transgene for herbicide resistance in oilseed rape has been detected in bacteria that live in the gut of honey bees. Although horizontal transmission of transgenes to close relatives of crop plants was expected, movement of transgenes into organisms other than closely related wild species was not anticipated.

Because of this instability and movement of transgenes it is impossible to predict where and when genetic changes may occur, what effect they might have on gene expression in host or other organisms, and what the environmental and human health effects might be. The application of transgenic technologies in agriculture extends beyond basic science into public policy and regulatory affairs where consumer safety and environmental protection are paramount.

Allergenicity. One of the health risks posed by GM foods is the possibility that eating proteins to which the human body has never been exposed may cause allergic reactions. An allergic reaction is a complex immune system response to a foreign substance. Typical symptoms include skin rashes, headaches, asthma, nausea, colic, and diarrhea. More serious reactions include difficult breathing, anaphylactic shock (a reaction to exposure to an antigen), and even death.

Allergic reactions can be worsened by other molecular conditions in a person's body or the environment. The only treatment for food allergies is dietary avoidance. Critical to avoidance is the ability to identify the source of exposure. Because GM products are not labeled in the United States, it is virtually impossible for consumers and clinicians to determine when symptoms that may be caused by an allergic reaction to food are caused by a GM ingredient.

Two criteria are currently used to gauge whether a transgenic protein is safe for human consumption. One compares the amino acid sequences of the transgenic products to the amino acid sequences of food proteins known to elicit allergic reactions. However, the critical criterion for predicting allergenicity involves subtle differences between similar proteins that are not picked up by computer programs and search engines currently available.

Another problem that cannot be detected by comparison of primary amino acid structure to proteins in databases is that allergic reactions are often caused by modifications to proteins after they are produced in the cell to accommodate their functional role in the body.

The second criterion for predicting allergenicity is the test tube assay, which measures stability of the transgenic protein to digestive enzymes. This assumes that food allergens exhibit more stability to digestion than other foods. However, such digestion assays are not reliable for determining food allergenicity because some major food allergens are broken down by gastric enzymes. These cannot be detected in the digestion stability assays.

Another flaw in the assay for assessing safety is these in-vitro (outside the body) tests use enzyme concentrations that are much higher than occur in the human digestive tract. Therefore, they do not adequately simulate how GM proteins will perform in the human gastro-intestinal tract. Furthermore, there is considerable variability in results from different laboratories because of lack of standardization.

People develop sensitivity to allergens depending on exposure, their developmental stage, and individual sensitivity. Babies and children up to age three are more sensitive to allergens because of their immature immune systems. Immune systems of the elderly are also more vulnerable because of age-related conditions. In the United States about 7 million people have documented food allergies.

A severe allergic reaction can cause anaphylactic shock, the most feared form of hypersensitivity, which can be fatal unless the person receives immediate emergency treatment. With ISO - 175 deaths per year from allergic reactions in the United States alone, there is a clear need for better understanding of the genetics and physiology of allergenicity and the molecular modulators that regulate the complex, enigmatic reactions to food allergens.

Although a possible benefit of biotechnology in the future could be to reduce the amount of allergic substances in foods, there are significant loopholes in current methods for assessing GM foods for possible adverse reactions in humans.

A dramatic incident illustrates that failing to have a comprehensive regulatory scheme to address the complex dimensions of genetics, toxicology, ecology, and evolutionary biology can have serious consequences. In October 2000 it was discovered that taco shells sold at a fast food chain tested positive for a GM corn approved only for animal feed.

StarLink was not approved for human consumption because of the possibility that it could cause allergic reactions. Since the revelation of the presence of StarLink corn in taco shells, it was found that millions of bushels of StarLink had gone to food processors and that the product was widely distributed in processed foods from corn chips and corn flakes to a wide array of products that contain a corn ingredient.

There were massive recalls, and EPA withdrew the manufacturer's permit to sell StarLink. A number of allergic reactions to the cry protein in StarLink were reported, and some were life threatening. This incident documented that widespread contamination of food by transgenic products that are unapproved for human consumption—but that are approved for other uses—is virtually unavoidable because of multiple opportunities and sources for human error in addition to natural cross-contamination in the fields.

The inadequacies of regulatory laws to ensure human health and environmental safety are beginning to be more widely recognized. Several bills were introduced in 2001 in the 106th session of the U.S. Congress to address these concerns.