Poster: Biotech risk assessment

Abs # 921: Grain composition and the concept of Substantial Equivalence

Presenter:	Astwood, James D, james.d.astwood@monsanto.com
Authors	Astwood, James D (A)   Reynolds, Tracey L (A)
Affiliations:	(A): Product Safety Center, Monsanto

Defining the composition of new biotech products is a key step in risk assessment, especially in the context of "substantial equivalence" or "comparative risk assessment". It is generally assumed that the composition of corn grain is fairly constant. To test this view, and to understand base-line variability in grain composition, 7 hybrid maize varieties grown at 4 different sites were analyzed for proximates, fiber, amino acids, fatty acids, vitamins, minerals, and secondary metabolite composition. Of 4935 comparisons, 40% were found to be statistically significant (p<0.05). More than a third of the comparisons at any one site or across combined sites were statistically different: This study has clearly demonstrated that analyte levels from maize hybrids grown in the same location can vary dramatically. A third of these statistical differences were greater than 20% different than the mean as a percent of the comparator line) and should be considered biologically relevant. These large differences in analyte levels underlines the importance of genetic background and breeding as determinants of biochemical composition and allows one to better understand the natural range of these components. Therefore, the levels of specific analytes are not static in corn grain. We conclude that the characterization of extant analyte variability is prerequisit to performing comparative risk assessments for biotech crops because natural variability will define the upper and lower boundies of acceptable composition. Thus, only those analytes which fall outside the boundries of natural variability will be relevant to further interogation with respect to safety and nutritional impact. The influence of environmental factors will be the focus of a future study.