Margin of Exposure
1. What is the margin of exposure (MOE) approach and how is it used?
The MOE is a tool used by risk assessors to consider possible safety concerns arising from the presence in food and feed of substances which are both genotoxic (that is, which may damage DNA, the genetic material of cells) and carcinogenic. The MOE is a ratio of two factors which assesses for a given population the dose at which a small but measurable adverse effect is first observed and the level of exposure to the substance considered.
Risk assessors at EFSA use the MOE approach to consider possible safety concerns arising from the presence in food and feed of substances which are both genotoxic and carcinogenic. The presence of substances which are both genotoxic and carcinogenic in food and feed, while not desirable, could result from environmental pollution or manufacturing processes.
The MOE is not used to assess the safety of regulated substances deliberately added to the food chain (for instance food and feed additives or food contact materials). However, EFSA’s Scientific Committee advised in a statement published in March 2012 that it could be useful in assessing the safety of any genotoxic and carcinogenic impurities present in such substances at very low levels. Use of the MOE can in this way help support risk managers in defining possible actions required to keep exposure to such substances as low as possible.
EFSA’s Scientific Committee published a first opinion in October 2005 recommending the use of the MOE approach for the safety assessment of contaminants that are both genotoxic and carcinogenic.
2. Did EFSA develop the margin of exposure (MoE) approach with any industry-backed group?
No. The approach developed by EFSA for use of the MOE was the work of its Scientific Committee made up of highly experienced scientists from across Europe, who have published widely in scientific literature and are extremely well placed to consider new methodologies for risk assessment.
More than 10 years ago, before EFSA was created, a number of international groups and advisory bodies had already begun to consider various approaches relevant for the assessment of the potential risks associated with the presence in food and feed of substances that are both genotoxic and carcinogenic, including Margin of Exposure. Among those groups was the European Commission’s Scientific Committee on Food (SCF), the precursor to EFSA.
Before it handed over its tasks to EFSA in 2002, the SCF had already started work on developing methodologies to further refine the general advice which was then given to risk managers regarding exposure to substances which are both genotoxic and carcinogenic. Scientists generally advise risk managers to reduce exposure to such substances to a level that is as low as reasonably achievable (known as the ALARA principle).
In 2004, EFSA asked its Scientific Committee to propose a harmonised approach for the risk assessment of substances that have both genotoxic and carcinogenic properties. In its opinion published in October 2005, the Scientific Committee recommended using the MoE approach.
In November 2005, EFSA and the World Health Organization (WHO) organised a conference to discuss the possible approaches for risk assessment of such substances, how the approaches may be interpreted and whether they meet the needs of risk managers. The conference was widely attended by scientists from across Europe, including ILSI Europe, which sent some of its scientific experts. EFSA, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and ILSI Europe each presented for discussion documents outlining approaches for evaluating the potential risks associated with the presence in food of substances that are both genotoxic and carcinogenic. These documents considered similar scientific data and reached similar overall conclusions that the MOE approach was a useful and pragmatic option for the risk assessment of substances that are both genotoxic and carcinogenic, and had the potential to improve the advice provided to risk managers.