1.2 Application of comparative approach

The strategy for GMMs assessment is based not only on evaluation of intended modifications, but also on the unexpected outcomes of the genetic manipulation process. It compares the GMM or GM food or feed with its conventional counterpart. This comparative approach is based on the concept that a conventional counterpart with a history of safe use can be taken as a referent point for the environmental, food and feed risk assessment of a particular GMM. In order to characterize this, OECD has developed concepts of “familiarity” and “substantial equivalence”, which were further worked out by ILSI and WHO/FAO. The risk assessment goals to identify new or altered hazards connected to the conventional counterpart. These comparative investigations could be used as a first step of the risk assessment. After, in the second step, both intended and unintended differences should be identified and their environmental and food/feed safety and nutritional impact should be assessed.

The information about concepts of “familiarity”, “body of knowledge:”, “history of safe use” and “substantial equivalence” is given below:

Table 2

The concept Description
“familiarity” and “body of knowledge” Majority of GMM strains used for food / feed purposes belong to well characterized microbial species. Such “familiarity” permits the risk assessor to draw on previous knowledge and experience with the introduction of similar microorganisms into food and environment, as well as to the results from risk / safety analysis, performed before scale up of technologies. This term is replaced by the new one – “body of knowledge”.
“substantial equivalence” This concept is based on the underlying principle that an existing microorganism with a “history of safe use” as food or feed can serve as comparator when assessing the safety of GM food and feed. Detailed description is given in ILSI and EFSA Scientific Colloquium on QPS.

Neither the concept “body of knowledge”, nor “history of safe use” guarantee creating no harm. In case the parental microorganism has been given a recognized status of QPS, all available information on the history of safe use has already been assessed.

The natural diversity of microbial genome becomes obvious in foods and during their processing as very complex microbial associations it may be a common event. Moreover, chemical and physical factors/characteristics of foods influence gene expression and cause variations. This peculiarity should be taken into consideration during safety assessment as a variety of data can be obtained in laboratory experiments with foods or in gastro-intestinal tract during ingestion. Thus, a concept for substantial equivalence should be applied to GMMs themselves as well as to the foods obtained using them. Here must be noted that application of a substantial equivalence concept should be done very precisely because minor differences can distinct pathogenic and non-pathogenic strains of microorganisms.

The main characteristics of the concept of substantial equivalence are involvement of a specific analysis of composition and phenotype of GMM and comparison to that of conventional parent strain. In this respect FAO and WHO noted in their report that it was necessary to keep in touch with the progress in new molecular methodologies. Their application provides a powerful tool for obtaining of detailed analytical information and can facilitate a successful comparison between the conventional and genetically modified microorganisms. In this respect to use DNA microarrays and proteomics techniques is especially convenient. Metabolic profiling of microorganisms trough a range of analytic techniques is an advanced approach, possessing special value in assessment of GMMs where metabolic rearrangement is the anticipated result

The application of such kind of technique is restricted by necessity of evaluation of a background in the normal variations and the significance of differences detected. Important steps should be carried out prior to considering these techniques in the routine assessment of safety:

  • Validation of methodology for insurance of their reproducibility and robustness
  • Achievement of agreement for assessing their performance (i.e. definition of the range of differences in one array/profile which can be considered as “normal variation”)

Evaluation of each difference in the profile which is not considered as a “normal variation”