Difficulties assessing the environmental impact of GM Crops

The world’s population is growing. By 2050 it is estimated that global population will breach 9.5 billion.

Regrettably the current world’s population is already straining the globe’s natural resources impacting the availability of agriculture land, causing increased erosion and desertification due to landuse change, water diversion and pollution of land and water resources. This along with a predicted average global temperature rise by 1.4-5.8ºC by 2100 increasing extreme fluctuations and weather events will put added stress on meeting the globe’s food and agro-product needs. It is important to ensure future food requirements can be met by the agriculture land in current use or less if the current area of agricultural land is reduced.

One of the methods proposed to meet this foreboding challenge is the use of genetically modified (GM) crops with, for example, increased yield and resistance to pests or draught. Questions regarding the safety of the technology to both the health of the consumer and damage to the environment has led to GM becoming and staying a controversial subject. Despite this 10% of global agricultural land was planted using GM crops in 2010, comprising of 11 different crops across 29 countries. By 2011 GM crops covered 395 million acres.

The potential of GM crops cannot be understated however it is important that Government policy makers as well as members of the general public have access to clear, impartial and robust reports and appraisals. Yet the information available seems to be inconclusive, even faulty with an apparent lack of subjectivity. After having been spoilt by the IPCC reports over the years the lack of a comprehensive report outlining degrees of certainty is frustratingly absent. Policy makers and the general public are left feeling bewildered and wondering who to trust.

We are told that there are significant environmental benefits in the use of GM crops. The reduction in global pesticide use is reported by Agobio Forum to have been reduced by 503 million kgs between 1996 and 2004, having a positive effect on the biodiversity of beneficial insects.

The reason for the reduction in pesticide use is the introduction of the ‘Bt’ gene into species of maize, cotton and soybean, this gene causes the production of the Bt toxin that acts as an insecticide killing pests species that prey upon it. Studies have been conducted into adverse effects on non-target species, such as the North American Monarch Butterfly (Danaus plexippus) although no significant impact has been observed in field trials in comparison to conventional pesticides.

Although the amount of pesticides used is reduced, due to Bt secretion pesticides are still present and scientists are looking to perform longterm studies on the accumulation of Bt concentrations within soils. GM crops are not the only source of the Bt toxin with the use of ‘natural’ Bt insecticide considered ‘safe’ for certified organic agriculture.

In addition to pesticide use the adoption of herbicide tolerant GM crops (HT crops) has the potential to alter agricultural herbicide use. HT crops are resistant to either glyphosate (Roundup) or glufosinate, two of the most common less-toxic forms of herbicides, enabling a shift to the use of less toxic herbicides with these crop species. Yet the use of less toxic herbicides has increased total herbicides used. HT maize, spring oilseed rape and sugar beet have been trialled in the UK with an observed range of environmental impacts including positive in the case of maize, on weed vegetation and populations that feed on them. The practice of using HT crops promotes low-till agriculture benefiting soil conservation by decreasing erosion from use of plows.

GM crops are not necessarily developed as replacements for conventional agricultural crops but can be produced with increased resistant to drought, high salinity levels and industrial waste to widen the viable range of available agricultural land.

GM crops represents an opportunity but all risks and benefits must be approached using the scientific method, they should be evaluated using science-based procedure on a case-by-case basis and compared to the use of ‘conventional’ agricultural practises, which we already know have a detrimental effect on the environment.

For a first impressions min-podcast on GMOs dictated by the author: “What do you think about GMOs?”

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Samanta Webster

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