Risk assessment of genotoxic chemicals according to EFSA

Margin of Exposure

In former days, the European countries used the approach of assessing genotoxic contaminants using the method of linear extrapolation and the slope factor. One can still find assessments in the EU based on this method. EFSA did however propose in 2012 another approach in its Statement on the applicability of the Margin of Exposure approach for the safety assessment of impurities which are both genotoxic and carcinogenic in substances added to food and feed. Here it is described to calculate a "Margin of Exposure" (MoE). This is the ratio between the exposure and the effect dose level. For the effect dose level EFSA uses a BMDL. In the paper the Scientific Committee reiterates its view expressed in 2005 that a margin of exposure above 10,000 is of low concern, if it is based on the BMDL10 of an animal study. This approach does not calculate risk quantitatively as the slope factor does.

Consequently the risk assessment of genotoxic carcinogens as promoted by EFSA follows a different calculation. First one has to define the intake of the genotoxic compound in food (per kg body weight per day) and then to compare it with the BMDL10 for carcinogenic effects of that compound. If the exposure is 10,000 times or more less than the BMDL the intake is safe for the consumer, if less than not safe.