Table of Contents

  • Exposure to a multi-component mixture of chemicals is part of everyday life and may affect both human health and the environment. Over the past 10–15 years the focus on the seriousness of the effects of exposure to such mixtures has increased. During recent years, the concern about combination effects of chemicals and especially endocrine disruptors has been further increased due to new scientific knowledge of “combination effects”. Several studies have shown that exposure to a combination of endocrine disrupting substances causes serious adverse effects at doses that, for the individual substance, do not lead to a significant effect.

  • The workshop was held on 13 and 14 October 2010 in Copenhagen, Denmark, with participants from the national authorities in Finland, Sweden, Norway and Denmark. It was arranged and chaired by the Danish Environmental Protection Agency and supported by the Nordic Council of Ministers.

  • There are several ways in which chemical substances can and may act together when present in mixtures. Effects may be synergistic, antagonistic, additive or independent. One approach to assessing the toxicity is to conduct a direct test of the mixture of concern but this will not provide information on the contribution of the individual substances. An assumption can be that each component will contribute to this overall effect even when present in doses or concentrations below their individual NOEL or NOEC (i.e. the concept of dose or concentration addition). Alternatively, another assumption is that only those toxicants that are present in doses that cause an effect greater than zero (the threshold) will contribute to the overall toxicity of the mixture (i.e. response addition or independent action.

  • There was a general acceptance among the participants that, in most cases, dose addition is a sufficiently robust default approach for the assessment of the combined effects of substances. Moreover, it was agreed that there is sufficient convincing scientific evidence on combination effects of ED to initiate regulation at an EU level.

  • It was agreed that combination effects could be addressed in human health risk assessment and environmental risk assessment by allowing that each substance could only contribute with a maximum of 10% to the total risk (i.e. a maximum Risk Characterisation Ratio of 0.1) or by introducing an extra Mixture Assessment Factor (MAF) of e.g. 10 for human health risk assessment and 100 for environmental risk assessment. It was also generally agreed that allocation of a certain fraction of the maximum permissible exposure to the individual regulatory schemes could be a way of preventing risk from the cumulative exposure to substances from sources regulated under different sector specific legislations, e.g. for food, water and environment. In food for instance, the maximum residual level for ED could be set at a certain fraction (e.g. 10%) of the Acceptable Daily Intake to take into account possible contributions from other sources.

  • The members of the two groups agreed that the existing regulatory framework is not sufficient to regulate combination effects of ED and other types of chemicals or to manage the risk resulting from combined exposure. It was suggested that Member States should explore the limitations of the existing legislation by providing examples of e.g. risk assessment, restrictions, and quality criteria that clearly show the need for a stronger regulation of this area. This would show the need for development of, for example, specific EU guidance on assessment of combination effects or for strengthening the legal provisions in existing legislation.