Presence of glyphosate in food products in South Africa of which maize or soybean is the primary constituent

[摘要] English: South Africa is considered a major GM crop producing country. The predominant GM trait in maize and soybean in South Africa is herbicide tolerance. Herbicide tolerant (HT) crops allow for the application of herbicide during the growing season to selectively kill weeds without damaging the crop. Glyphosate is the most widely used herbicide on HT crops in South Africa and the world.Glyphosate is absorbed by HT crops after application. Studies have detected levels of up to 2.2 mg/kg in HT maize and 26 mg/kg in HT soybean. Glyphosate is not removed from grain by washing, cooking or processing. As a result of this, glyphosate can also be detected in processed food products. It has also been found that glyphosate can be detected in animal tissue and urine after exposure to the herbicide through feed. Similarly, glyphosate has also been detected in the urine of humans, either as a result of occupational exposure, through diet and/or water.Pure glyphosate is considered safe by regulatory authorities and international bodies. However, recent studies have found that glyphosate in formulation at low concentrations results in endocrine disruption as well as DNA and chromosomal damage. As a result of this, the IARC re-classified glyphosate as a 'probable human carcinogen. Glyphosate is used on HT maize, a major staple food, and HT soybean, an important source of protein, in South Africa. Thus, the aim of this study was to determine whether glyphosate is present in commercially available South African food products containing maize and/or soybean as a primary constituent.The majority of food products tested in this study contained glyphosate. The level of glyphosate ranged from 0.027 mg/kg to 2.257 mg/kg that is below the MRL and ADI established in South Africa. However, recent studies have shown that glyphosate in formulation is genotoxic at the levels found in maize and soybean containing foods in South Africa. The results from this study found that the level of glyphosate in food products in South Africa is comparable to the limited number of studies from the UK and USA. This study is unique to other published studies since it focused on food products likely to be consumed daily. This study has confirmed that South Africans are exposed daily to low levels of glyphosate through food products.The GM HT events in the food products were quantified in order to explain the variation in the levels of glyphosate. It was determined that 57 products contained one or more GM HT event in a range of 0.25% to 100%. However, there was no correlation between the level of glyphosate and percentage GM HT event in the products, even when GM HT negative samples were excluded from the analysis. This suggests that either glyphosate is not applied to some GM HT crops, when weed control is not required, or that the herbicide is applied to non-GM crops as a desiccant prior to harvesting.Most of the food products used in this study were labelled in terms of GM content. The percentage GM HT event(s) in the food products was used to determine compliance to mandatory GM labelling in South Africa since the data was available. Results indicated that the majority of companies in South Africa are compliant with the Consumer Protection Act (2008) concerning GM labelling. However, most of the products labelled 'GMO free, did not comply with the expectation of discerning consumers.To conclude, this is the first study to investigate the extent of glyphosate in South African food products. This study has confirmed that South African consumers are exposed to low levels of glyphosate as a result of consuming maize and soybean food products. The level of glyphosate detected in the food products although considered low, is at a concentration reported to cause genotoxic effects at cellular level by in vitro studies. It is currently not known what the safety implications are of chronic exposure to glyphosate, through the consumption of a staple like maize meal and soybean in South Africa. The question of whether glyphosate in food is safe in the long term needs to be addressed through future research.

[发布机构] University of the Free State