GMOs - environmental concerns

Genetic modification is a contentious issue. This article looks particularly at how it is used in crops, and the environmental risks. See also an introduction to GMOs, GMOs - health concerns, GMOs - political and ethical concerns, and GMOs - the future.

The issues are complex. But GM is unlikely to go away. As organic growers and suppliers – the more we understand the subject, the greater strength we have in order to influence safety regulations, to prevent contamination, and to encourage governments to support growers and farmers to use other less invasive crop cultivation.

What is Genetic Modification?

A Genetically Modified Organism (GMO) is one whose genetic material (DNA) has been added to, removed or changed.

Genetic engineering allows scientists to insert desired traits or features into an organism – enhancing a crop’s resistance, for instance. This artificial manipulation of DNA would never happen in nature. It replaces the traditional method of selective breeding, a common and completely safe practice used by growers. European law defines a GMO as an organism in which “the genetic material has been altered in a way that does not occur naturally by mating and/or natural recombination."

There are many environmental concerns about GMO crops. We concentrate on just three:

1. Increased use of toxic herbicides and pesticides

The majority of GM crops are those which have been engineered to be herbicide resistant. ‘Roundup ready’ soya, produced by Monsanto, is grown extensively in North and South America. It allows farmers to spray with a toxic cocktail of glyphosate and other chemicals. This may not harm the crop – but it does create residues and run off, making it disastrous for surrounding ecosystems. See Glyphosate.

It also encourages the development of ‘superweeds’ which are resistant to glyphosate, such as the giant pig weed, which grows over 2m tall.

Morning Glory is another weed which has developed resistance to glyphosate. This paper reveals how the plant has evolved a reproductive system which ensures its tolerance of glyphosate. Something not predicted by the genetic engineers. "What kind of evolution are we causing due to impacts that we didn't quite foresee?"questions researchers from the University of Michigan.

Since the introduction of GM, there has been a dramatic increase in the use of glyphosate worldwide.

Proponents of GM argue this is cheaper and simpler weed management for farmers, it reduces tillage (and therefore carbon loss) and that it does not harm the environment or our health (believing glyphosate to be safer than other herbicides).

Critics of GM recognize the terrible damage to the life forms surrounding the crops. The risk to beneficial insects such as pollinators, the residues left in the soil, and the run off into fresh water sources such as rivers and streams. But there is also the potential health risk for humans and animals who consume the crops. See Health concerns.

The response, unfortunately, is to create GM crop varieties which are resistant to multiple herbicides, such as Dow’s multi-herbicide soybean, engineered to tolerate glyphosate, glufosinate and 2,4-D (an ingredient of the defoliant Agent Orange.) See What are Superweeds? It appears this chemical treadmill benefits GMO seed companies, who also produce the agrichemicals.

2. Pleiotropy.

DNA is a complex structure. It is not like Lego - altering it in any way can create new consequences in the cell’s composition, as well as its relationship with other cells. Chemists call this Pleiotropy. In every organism, genes, proteins and pathways do not act as isolated units but interact with one another and are regulated in a complex, multi-layered network process. Such is the wonder of natural life.

Despite scientists’ claims to ‘solve’ a problem, it is impossible to predict the impacts of even a single gene modification. Pleiotropic effects have included alterations in the crop’s nutritional, toxic and allergenic properties. For example, a GM soya tested in 1996, had 27% higher levels of a major allergen, trypsin-inhibitor, than the non-GM parent variety. GM Bt insecticidal maize, tested in 2008, had an altered protein profile, including the appearance of a new form of the protein zein, which is a known allergen. See

Even the new technique, called CRISPR, heralded for it's accuracy, still has unknown effects on non-targeted cells. CRISPR scientists rely on algorithms to predict the most obvious cell changes, but in a recent test case there were 100s of unforeseen effects - none of which would be picked up by the indadequate testing carried out to comply with GMO regulation. See Health concerns.

For the scientists among us, this report explores the mutational consequences of genetic engineering.

3. Contamination

GM crops can – and do - cross pollinate with wild and non-GM plants. Other sources of contamination are the inadvertent spread of seed by farm machinery, as well as mixing seeds during storage.

Cross pollination will not only contaminate wild plants, affecting their natural genetic makeup, but will seriously compromise any organic or non GM farming system. Despite claims that GM and non-GM can co-exist, it is patently untrue.

Search the internet for ‘Co-existence of GM crops’ and you will find a slew of papers which confirm the unrealistic claims of spatial regulation between pollinating crops. For economic and geographical constraints, farmers cannot be expected to isolate their GM crops. Organic farmers will lose their registration, and in Canada, for instance, it is now virtually impossible to cultivate non-GM oilseed rape, such is the overwhelming GM presence.

Recent examples from the Contamination Register include the arrival in the UK in 2015 of some genetically modified rape seed in a consignment of conventional seed from France. DEFRA was forced to destroy the crop and the consignment. Germany found GM Bt resistant rice (see GMO Health concerns) in organic rice flour imported from China.

New genetic engineering techniques, such as CRISPr, increase the danger of plants with altered genes spreading throughout whole wild populations. A gene 'drive’ system allows for an edited gene on one chromosome to copy itself into its partner chromosome. The result is that nearly all offspring will inherit the engineered gene. If just a few organisms with gene drives are released into the wild, the whole population could end up with the edited gene. See New Genetic Engineering.

For further reading on the effect of genetic engineering on the natural environment, we recommend reading GMO Myths and Truths (2015) Robinson, Antoniou, Fagan.