Does chronic contact to xenobiotic compounds in the human digestive tract carry health risks? Do GMOs contain any molecules that do not naturally occur in nature?

Expert response from Community Manager

Friday, 12/12/2014 12:41

This is not a simple question to answer, since it is pretty much the basis of the entire field of toxicology. To start, though, let me summarize my response to your question.

• The composition of GMOs is tested extensively to determine if they are equivalent to the composition of non-GMOs (and therefore equally safe); 
• GMOs may contain xenobiotic chemicals but are no more likely to contain them than non-GMOs;
• The presence of xenobiotic chemicals does not mean that they are dangerous, because we are routinely exposed to them.

Allow me to break my down answer into more detail. First, the word “xenobiotic” may not be familiar to everyone. It simply refers to chemicals that are not naturally produced in the organism consuming them. In this case, you are referring to chemicals that are not produced by humans. 

The foods we eat are a collection of chemicals, whether they are further processed or in their raw form found in nature. Some of these chemicals are identical to those our bodies produce, like certain amino acids, and would not be considered xenobiotic. Other chemicals found in food, including vitamins and minerals with important nutritional value, are xenobiotic. So you can see that the mere classification of something as xenobiotic does not necessarily mean that it is hazardous.

Foods from GMOs on the market today are no more likely to contain xenobiotic chemicals than the same foods from non-GMO sources. We know a lot about the composition of soybeans and corn. One of the most important tests we do before commercializing a new GMO is one that analyzes and compares the concentrations of all the major nutrients and antinutrients in the GMO to those same substances in non-GMOs. If a new GMO is to continue on in the development process, it must be equivalent to — and therefore as safe as — its non-GM counterpart. 

The processes used to produce GMOs do not introduce complex enzymatic systems that are capable of producing new compounds that are not also present in non-GMOs. In fact, the modification in most cases is limited to expression of one or more proteins with a very narrow range of activity, such as metabolism of an herbicide, or pesticidal activity toward a particular insect. One exception would be the introduction of herbicide-tolerating enzymes that could produce new metabolites when treated with an herbicide as a process of tolerance toward that herbicide. GMO crops and pesticides are thoroughly tested and subject to strict government review before they come to market. 

Expert response from Laura Privalle, Ph.D.

Global Head Regulatory Field Study Coordination, BASF

Friday, 07/11/2014 16:53

To answer the first question, we must consider the definition of “xenobiotic compounds.” According to the Merriam-Webster dictionary, a xenobiotic is “a chemical compound (such as a drug, pesticide, or carcinogen) that is foreign to a living organism.” By this definition, xenobiotics that are carcinogens cause cancer, for example. So, yes, chronic contact to some xenobiotic compounds can carry health risks.

In answer to your second question: neither non-GM plants nor GM plants contain molecules that do not naturally occur in nature. However, any plant (conventionally, organically or genetically grown) that has had crop-protection solutions applied to it may contain xenobiotics.

What makes GMOs unique and different from conventional plants is that humans have introduced new genes into them. These genes encode proteins that are produced in the plant. Proteins are not foreign to living organisms. They naturally occur in nature and are in fact essential for life (think about what you had for lunch).

We must consume certain quantities of proteins in order to live. Among plants, legumes and nuts have the highest protein levels. All proteins, including the newly produced ones in GMOs, consist of the same 20 amino acids. The proteins we consume are digested to their component parts — amino acids. We take up these amino acids in our digestive system and synthesize our own proteins within our bodies. The specific proteins that are produced in GMOs are found in nature. Bt proteins are found in a soil bacterium known as Bacillus thuringeinsis. Many of the herbicide-resistant proteins are found in other bacteria (such as Agrobacteria) or in plant species (such as corn).