Expert response from Bruce M. Chassy
Professor Emeritus of Food Safety and Nutritional Sciences, Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign
Tuesday, 25/11/2014 11:16
For all meaningful purposes, the answer is no, but it’s seldom that simple. Let’s review quickly that the differences in most crops from GM methods and traditional breeding are a protein (1 new protein of 30,000 background proteins) and a gene sequence (on average, 0.0003 percent of the DNA). Notice that I said a “new protein” or “gene sequence,” since proteins and DNA are made of amino acids and nucleotides, respectively. The GM-derived amino acids and A’s, C’s, T’s and G’s are exactly identical to those in the original crop. The modern scientific methods of detection and analysis are extremely sensitive and becoming more sensitive each year, as clever researchers develop better analytical strategies and equipment.
It also makes a big difference which of the several products I mentioned is being analyzed, as will be explained below. For some (sugar and alcohol, for example), the answer today is no. For starch, on the other hand, it may be possible to detect infinitesimal amounts of DNA or proteins (see below). The important thing to remember is that not only are the amounts of DNA and protein present in any of these products exceedingly difficult to detect, but it is inconceivable that they could cause harm —first, because so few of them are present, if they are there at all, but more important because thorough, careful study has shown that the proteins and DNA that are present in genetically engineered foods and feeds are as safe as, or safer than, any others to consume.
The distillation process used in producing alcohol (ethanol), from wet- or dry-milled corn, assures no carryover of protein or DNA in the ethanol. Therefore, it is impossible to differentiate between 200-proof ethanol produced from transgenic corn and the same type of ethanol produced from nontransgenic corn.
A second fraction for which the detection of novel proteins or DNA is highly unlikely is for refined sugar products. For corn, the starting point for the production of refined sugar products is purified starch. The starting starch component has a purity of 99.5 percent, with a protein content of 0.3 to 0.35 percent. Presumably, DNA/RNA constitutes a significant proportion of the remaining 0.2 percent of the contaminants for the purified starch. Acid hydrolysis generates free sugars from the purified starch with hydrochloric acid at elevated temperatures and pressures, or through the use of enzymatic hydrolysis. Additional steps are taken to remove DNA and protein from this sugar-containing matrix, so it is unlikely that novel DNA or protein would be detected in refined sugar products derived from corn or sugar beets.
Because purified corn starch contains low levels of protein and DNA, detection of novel DNA and protein in purified starch is possible. Novel DNA can be detected in corn starch, given the ability of modern PCR methods to detect pg (10-12) amounts of DNA. The detection of novel proteins is possible in corn starch, but the method would need to be able to detect this one protein present in the starch at less than 0.1 ppm (equivalent to one-half drop in a 55-gallon barrel).
The detection of novel proteins in highly refined corn oil is extremely unlikely, given that 100 ml of oil would contain 0.16 ng (10-9) of the novel protein. This would be very difficult to detect using current immunological methods.
If I may presume a follow-up question, you might be wondering whether a product with processed fractions derived from a GM crop could (not “may”) be “labeled” as non-GM. I guess the simple answer here is that it could conceivably happen, and it would require tracing these fractions back to the farm to ensure that this does not occur.
Video: GMO Answers at SXSW