Study shows current buffer zones as recommended by EFSA are "inappropriately small"

Monitoring data from Germany, Switzerland, and Belgium show that maize pollen can travel for over four kilometers, according to a new study. This means that buffer zones around GM maize are required to be "in the kilometer range" in order to prevent harmful exposure of non-target organisms, such as butterflies.

Currently the European Food Safety Authority (EFSA) only recommends buffer zones of only 20 to 30 metres between Bt maize and protected habitats of extremely sensitive butterfly species. The authors of the new study say their data shows that such buffer zones are "inappropriately small".

It's yet another example of the gross inadequacy of GMO regulatory regimes, even in Europe, which has a stricter system than other countries.

These data also show that the proposal to allow some EU countries to grow GM crops will rapidly result in contamination of neighbouring countries' crops.


Maize pollen deposition in relation to distance from the nearest pollen source under common cultivation - results of 10 years of monitoring (2001 to 2010)

Frieder Hofmann, Mathias Otto and Werner Wosniok
Environmental Sciences Europe 2014, 26:24. 17 October 2014
Open access:


Information on pollen dispersal is essential for the risk assessment and management of genetically modified organisms (GMOs) such as Bt maize. We analyzed data on maize pollen deposition at 216 sites in Germany, Switzerland, and Belgium from 2001 to 2010. All data were collected using the same standardized sampling method. The distances between sampling site and the nearest maize field ranged from within the field to 4.45 km.

Maize pollen deposition was negatively correlated with distance from the nearest pollen source. The highest pollen deposition was within the field, but depositions of several thousand pollen grains per square meter were recorded over the kilometer range. A power function model most accurately described the relationship between deposition and distance from the nearest pollen source, rather than the exponential model currently used in EU risk assessment and management, which underestimates exposure for distances greater than 10 m. Regression analysis confirmed the high significance of the power relationship. The large variation in pollen deposition at a given distance reflected the influences of wind direction and other meteorological and site conditions. Plausible variations of single values and the predicted mean pollen count at a given distance were expressed by confidence intervals.


The model described here allows estimations of pollen deposition in relation to distance from the nearest field; therefore, it will be valuable for the risk assessment and management of GMOs. Our results indicate that buffer zones in the kilometer range are required to prevent harmful exposure of non-target organisms to GMOs.