THIRD WORLD NETWORK BIOSAFETY INFORMATION SERVICE
Dear Friends and Colleagues
Risks of Glyphosate Residues in Food and the Environment
Glyphosate has been the most widely used herbicide in the world for the past three decades. It use has expanded greatly with genetically engineered herbicide-tolerant crops. A new study has reviewed recent literature to assess the possible risks associated with the presence of glyphosate residues in food and the environment. It reports that research has found thatglyphosate and its major metabolite, aminomethylphosphonic acid, AMPA, residues can persist in the environment and that the contamination of soil, water and some food occurs at concentrations that may pose ecological risks.
In 2015, the European Food Safety Authority (EFSA) reported that glyphosate and its major metabolite, AMPA, may be present in food consumed by humans. This review has found that it is not only possible, but also that chronic glyphosate exposure at low concentrations can potentially result in risks to human health. This review also revealed a striking lack of food residue analyses of glyphosate and AMPA in the peer-reviewed literature, including a complete absence of data for any species of fish.
This review adds to growing literature debunking the findings of many earlier studies that glyphosate did not pose a risk to people or the environment, and exposes the limitations of their methods of analysis. The researchers call for additional studies that analyse glyphosate and AMPA residues in food and explore the potential of chronic glyphosate toxicity to ensure that any continued use of glyphosate delivers minimal environmental contamination and no impact on human health.
We reproduce below the Abstract and Conclusion of the review.
With best wishes
Third World Network
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GLYPHOSATE: ENVIRONMENTAL CONTAMINATION, TOXICITY AND POTENTIAL RISKS TO HUMAN HEALTH VIA FOOD CONTAMINATION
by Bai, S. H., & Ogbourne, S. M.
Environmental Science and Pollution Research
doi: 10.1007/s11356-016-7425-3. 2016. https://link.springer.com/article/10.1007/s11356-016-7425-3
Abstract
Glyphosate has been the most widely used herbicide during the past three decades. The US Environmental Protection Agency (EPA) classifies glyphosate as ‘practically non-toxic and not an irritant’ under the acute toxicity classification system. This classification is based primarily on toxicity data and due to its unique mode of action via a biochemical pathway that only exists in a small number of organisms that utilise the shikimic acid pathway to produce amino acids, most of which are green plants. This classification is supported by the majority of scientific literature on the toxic effects of glyphosate. However, in 2005, the Food and Agriculture Organisation (FAO) reported that glyphosate and its major metabolite, aminomethylphosphonic acid (AMPA), are of potential toxicological concern, mainly as a result of accumulation of residues in the food chain. The FAO further states that the dietary risk of glyphosate and AMPA is unlikely if the maximum daily intake of 1 mg kg−1 body weight (bw) is not exceeded. Research has now established that glyphosate can persist in the environment, and therefore, assessments of the health risks associated with glyphosate are more complicated than suggested by acute toxicity data that relate primarily to accidental high-rate exposure. We have used recent literature to assess the possible risks associated with the presence of glyphosate residues in food and the environment.
Conclusion
Glyphosate is the most widely used herbicide in the world and its demand continues to grow. Although, the majority of glyphosate is mineralised following application, the half-lives of glyphosate and its metabolites are long under certain conditions, and glyphosate and AMPA residues can persist in soil, water and plants in some circumstances. In fact, recent research suggests that contamination of soil, water and some food occurs at concentrations that may pose ecological risks.
However, the majority of literature concludes that the levels of contamination do not pose a risk to most organisms and are unlikely to cause an environmental risk, if recommended application rates are followed and repeat applications are avoided.
In 2015, the EFSA reported that glyphosate and its major metabolite, AMPA, may be present in food consumed by humans. Whilst it is unlikely that human exposure will reach TMDI levels through consumption of contaminated crops or other food, this review showed not only that it is possible, but also that chronic glyphosate exposure at low concentrations can potentially result in risks to human health. However, this review also revealed a striking dearth of glyphosate and AMPA food residues analysis in the peer-reviewed literature, including a complete absence of data for any species of fish.
More recently, and despite conflicting reports in the literature, the carcinogenic classification of glyphosate was changed to ‘probably carcinogenic to humans’ by the IARC, a classification based on limited evidence of carcinogenicity on human studies but sufficient evidence from animal research (Guyton et al. 2015). However, this classification was rejected by European Food Safety authorise (EFSA 2015). Taken together, completion of additional studies that analyse glyphosate and AMPA residues in food and that explore the potential of chronic glyphosate toxicity seems prudent.
Glyphosate is a valuable and important weed management tool for agricultural professionals and hobby gardeners alike. However, in the light of recent research, there is a need to identify the most sensitive environmental and toxicological scenarios to inform future best practice management for glyphosate use such that it can remaineffective, whilst ensuring minimal environmental contamination and no impact on human health.