The European Food Safety Authority has published a draft report on ways to strengthen existing methods for assessing allergenicity of genetically-modified organisms, and is seeking comments from stakeholders.

EFSA's existing guidance recommends step-by-step, case-by-case assessment of GMO allergenicity that draws conclusions based on the weight of evidence. Such an approach is in tune recommendations from the Codex Alimentarius Commission.

The new draft report stands by this method, but seeks to update this guidance - and make the weight-of evidence approach stronger - by taking account of the latest developments in clinical aspects of allergic reactions, structural aspects of GM food and feed, in silico approaches, IgE binding studies, cell-based methods, profiling techniques and animal models.

Amongst the general recommendations, it suggests optimising the search for sequence homology and structural similarities by having comprehensive, good quality allergen databases.

"In general, the alignment based criterion involving 35 per cent sequence identity to a known allergen over a window of at least 80 amino acids is considered a minimal requirement," it says.

For measuring the capacity of a newly expressed protein to bind serum IgE from allergic individuals, the report recommends using sera from well-characterised individuals rather than pooled sera.

And improvements to the physiological conditions in which in vitro digestibility tests are carried out are suggested, to take into account the impact of the food matrix and processing, as well as the pH value and protein-to-enzyme ratio in the stomach. Moreover, infants and others may have different digestive physiology, and that should be taken into consideration.

Whole foods and beyond

When it comes to assessing a whole GM food, the report suggests including allergens in a list of compounds for comparison between the GM plant and its non-GM equivalent, and to conduct qualitative and quantitive comparisons taking into account cultivars' natural variability.

The draft report also makes some suggestions about additional testing that could be conducted. This includes animal models, and developments on 3-dimensional structure of allergens, profiling technology, post-market monitoring and exposure assessment.

The report is available here .

EFSA is accepting comments via its online system until 31 January 2010.