Brussels, 04 Nov 2005
In an opinion published on 3 November, the Scientific Committee of the European Food Safety Authority (EFSA) proposes a harmonised and transparent scientific approach from Europe to the risk assessment of substances which have both genotoxic and carcinogenic properties.
Genotoxic and carcinogenic substances have the potential to directly interact with genetic material (DNA) in the cells of the body and to cause cancer. It is thought that any exposure is undesirable since there may be a risk associated with exposure even to low amounts, especially if consumed on a regular basis. This opinion focuses on exposure to food. One of the most difficult issues in food safety is to advise on the potential risks to human health for these substances.
As there is currently no international scientific consensus on the best approach for assessing this risk and as different approaches are used around the world, the European Food Safety Authority asked the Scientific Committee to propose a harmonised EU approach.
In many countries and especially within the European Union, the current rule is to reduce exposure to such substances to a level that is 'as low as reasonably achievable', known as the ALARA principle. However, such advice does not provide risk managers with a basis for setting priorities for action, either with regard to urgency or the extent of necessary measures. Several of the approaches currently used for the risk assessment of these substances take into account the fact that some carcinogens are more likely than others to induce a tumour at a given dose (potency). Information about potency is mostly derived from laboratory studies on rodents, since human data are rarely available. In these studies, animals are exposed to the substances of interest at high dose levels for the major part of their lifetime, so that any detectable and statistically significant tumour incidence can be identified.
To provide advice on the possible consequences for humans, the significance of these animal results must be interpreted in the context of human exposure levels, which are usually much lower than the doses used in laboratory studies. A wide range of models have thus been developed to convert the results from animal studies into data consistent with the exposure experienced by humans. This approach is, however, unreliable as the data changes in accordance with the model used.
The Scientific Committee therefore recommends using a different approach, known as the margin of exposure (MOE) approach. The MOE approach uses a reference point, often taken from an animal study and corresponding to a dose that causes a low but measurable response in animals. This reference point is then compared with various dietary intake estimates in humans, taking into account differences in consumption patterns. The margin of exposure approach can be applied in cases where substances that are both genotoxic and carcinogenic have been found in food, irrespective of their origin, where there is a need for guidance on the possible risks to those who are, or have been, exposed.
With respect to the selection of human intake estimates, the Scientific Committee recommends that different exposure scenarios (for the whole population and for specific groups of the population) should be provided, depending on the substance considered and its distribution in the diet.
Moreover, the Scientific Committee is of the opinion that substances which are both genotoxic and carcinogenic should not be approved for deliberate addition to foods or for use earlier in the food chain if they leave residues which are both genotoxic and carcinogenic in food.