A new study reveals how GM contamination occurs and gives pointers as to how it might be avoided
By Claire Robinson
Genetically modified genes are still getting into native Mexican maize varieties, a new study has found. This is in spite of the fact that the cultivation of GM maize is banned in Mexico, which is the genetic center of origin for the crop. The study also identifies the crucial factors that decide whether or not GMO contamination occurs: the social organization and seed management systems of local communities.
The study, led by Dr. Sarah Agapito-Tenfen, is the latest in a series that have found GM contamination in native Mexican maize varieties, beginning with David Quist and Ignacio Chapela’s investigation in 2001.
While these studies focused on whether or not GMO contamination was found in native Mexican maize, the vital question of how it might have got there was given less attention. The studies sampled farmer seeds and fields without collecting information on the social context in which the seeds were produced and maintained over time. Dr Agapito-Tenfen’s study aims to fill this knowledge gap.
Study of two communities
The researchers visited the Oaxaca region and collected samples from two communities for analysis, called in the paper Community A and Community B. In Community A, farmers grew native (“landrace”) maize and hybrid maize. They saved seed but also shared it outside the community. Farming decisions were taken at an individual level and fields were owned as individual property.
Community B was more isolated in terms of location. Its people had a strong history of organization and defense of their rights, territories, and autonomy. Farmers grew only native maize. They saved the seed and only shared it within the community. Decisions made by the community had led to a ban on the replacement of traditional seeds by hybrid maize or maize from outside the community.
The researchers tested 57 samples: 13 from stores and local markets (12 in Community A and 1 in community B); 40 farmer samples; and 4 control samples. In Community A, six out of the 32 samples tested (18.75%) were positive for GMO contamination. In contrast, the samples from Community B were negative for GMO presence.
Knowledge to minimize GM contamination
The authors concluded, “Our results suggest that transgenes are highly likely to be present in Mexican maize landraces and importantly that the extent and frequency at which transgenes can be found will very much depend on the seed management practices and societal characteristics of the different communities engaged in maize farming.”
Dr. Agapito-Tenfen told GMWatch that the GMO contamination is coming from U.S. corn imports and is being spread through an informal system of farmer seed sharing practices.
But the authors point out that once Mexican people become aware of the mechanisms through which GM genes are getting into native crops, this knowledge can be used by farmers and community leaders to minimize GMO contamination.