Anti-GM logic doesn’t add up

Richard Heath

The debate over the safety of foods derived from non-conventional breeding methods is once again hitting the headlines, thanks to the proposed deregulation of a range of new breeding techniques.

Opponents of genetic modification (GM) in food maintain that the technology has too many unknowns and is therefore unsafe. In a survey conducted by the Pew Research Centre in 2014, 57% of Americans said it’s generally ‘unsafe to eat genetically modified foods’ (1), and sales of non-GM food have been rising each year.

The implication is that we can only trust conventional (‘natural’) breeding methods and must be cautious of anything not derived from ‘natural’ breeding. However, there is a large logic gap in this argument that will be tested by some of the new breeding methodologies now under regulatory review.

Following a 12-month technical review, Australia’s gene technology regulator Raj Bhula has proposed that gene editing techniques such as CRISPR should be less regulated.(2) CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) is a technique that edits a short sequence of DNA within an organism; no new or foreign DNA is introduced as a result of the process. For example, CRISPR has been used to remove the gene that makes barley susceptible to powdery mildew, without any other change to the barley genome.

Dr Bhula said that the case for deregulation was supported by the fact that the genetic outcome of using gene editing techniques was the same as that derived from breeding processes used for thousands of years, with a safe history of use.

‘If there is no risk case to be made when using these new technologies, in terms of impact on human health and safety for the environment, then there is a case for deregulation.’

One of the arguments used by those opposed to deregulation of these technologies is the ‘no problems – yet’ approach; that even though the crops or animals produced via gene editing may have the same genetic makeup as those bred using conventional techniques, there may be unanticipated or unobservable impacts in the short term which need a much longer timeframe of observation and testing before they can be considered safe. Therefore, says this argument, we should stick with conventional breeding techniques which we know are safe.

This is where the logic gap comes into play. Just because traditional breeding techniques have been performed for a long time doesn’t mean that the outputs are automatically safe.

The most toxic substances known to man are not man-made but originate from the natural world – for example, the botulism toxin, which is a result of ‘natural’ breeding between two organisms. In an evolutionary sense, the toxic substance produced by an organism may have originally been a genetic accident that inferred an evolutionary advantage and thus was fixed into the gene pool.

Every time two organisms combine their DNA through conventional breeding, new combinations of genes and DNA sequences are created. In plant or animal breeding when crosses are made this has the potential to result in unintended adverse genetic outcomes. In most circumstances the unintended outcomes are observable, and the progeny are not selected for continued breeding. It is completely possible however that adverse genetic outcomes not immediately observable – including the production of toxic or allergenic substances – are also produced.

Potatoes and tomatoes are two crops which both naturally produce steroidal glycoalkaloids, which are toxic to humans. Conventional breeding techniques can result in an increased expression of glycoalkaloids to a point where they become hazardous to humans. There are recent examples of commercial potato varieties (eg the Magnum Bonum in Sweden) being removed from market because elevated levels of glycoalkaloids were detected.(3)

Glycoalkaloids are a known problem; but conventional breeding can also result in entirely new foods being created with no previous exposure to humans. Kiwifruit were originally an unpalatable hard berry before being conventionally bred into the fruit that we know today. After they were commercially released some people developed allergic reactions to eating them, and long after release the allergenic compound was isolated and characterised.(4)

People opposed to new breeding technologies say that they should be restricted or banned because we don’t know the long-term outcomes of new compounds that might be produced, and that we should stick to conventional breeding techniques. However, known adverse outcomes from conventional breeding happen reasonably often – with no regulatory control or oversight. New breeding techniques result in minimal genetic change, are subject to a huge regulatory and testing regime and have had no demonstrated adverse outcomes from commercial releases. Conventional breeding results in random genetic recombination, has produced known adverse outcomes and is unregulated to test for these outcomes.

The logic that says that conventional breeding techniques are safer for human health than new gene editing methods just doesn’t stack up.





Image:  United Soybean Board