The use of adverse outcome pathways in the safety evaluation of food additives

In the last decade, adverse outcome pathways have been introduced in the fields of toxicology and risk assessment of chemicals as pragmatic tools with broad application potential. While their use in the pharmaceutical and cosmetics sectors has been well documented, their application in the food area remains largely unexplored. In this respect, an expert group of the International Life Sciences Institute Europe has recently explored the use of adverse outcome pathways in the safety evaluation of food additives. A key activity was the organization of a workshop, gathering delegates from the regulatory, industrial and academic areas, to discuss the potentials and challenges related to the application of adverse outcome pathways in the safety assessment of food additives. The present paper describes the outcome of this workshop followed by a number of critical considerations and perspectives defined by the International Life Sciences Institute Europe expert group.

Value and limitation of in vitro bioassays to support the application of the threshold of toxicological concern to prioritise unidentified chemicals in food contact materials

Some of the chemicals in materials used for packaging food may leak into the food, resulting in human exposure. These include so-called Non-intentionally Added Substances (NIAS), many of them being unidentified and toxicologically uncharacterized. This raises the question of how to address their safety. An approach consisting of identification and toxicologically testing all of them appears neither feasible nor necessary. Instead, it has been proposed to use the threshold of toxicological concern (TTC) Cramer class III to prioritise unknown NIAS on which further safety investigations should focus. Use of the Cramer class III TTC for this purpose would be appropriate if amongst others sufficient evidence were available that the unknown chemicals were not acetylcholinesterase inhibitors or direct DNA-reactive mutagens. While knowledge of the material and analytical chemistry may efficiently address the first concern, the second could not be addressed in this way. An alternative would be use of a bioassay capable of detecting DNA-reactive mutagens at very low levels. No fully satisfactory bioassay was identified. The Ames test appeared the most suitable since it specifically detects DNA-reactive mutagens and the limit of biological detection of highly potent genotoxic carcinogens is low. It is proposed that for a specific migrate, the evidence for absence of mutagenicity based on the Ames test, together with analytical chemistry and information on packaging manufacture could allow application of the Cramer class III TTC to prioritise unknown NIAS. Recommendations, as well as research proposals, have been developed on sample preparation and bioassay improvement with the ultimate aim of improving limits of biological detection of mutagens. Although research is still necessary, the proposed approach should bring significant benefits over the current practices used for safety evaluation of food contact materials.