Christina Rudén is Professor in Regulatory toxicology and ecotoxicology at the Department of Environmental Science, Stockholm University, Sweden.
Her research focuses on analyzing and evaluating the foundations and workings of EU chemicals legislation, and how science is used for regulatory decision-making. The overall purpose is to contribute to developing scientifically well-motivated improvements of the legal system and its practices. Rudén has published some 75 articles about regulatory toxicology in international peer reviewed journals.
She is a member of the Swedish Chemicals Agency’s Supervisory Council. She is representing Stockholm University as an observer in the CARACAL (Competent Authorities for REACH and CLP) and she is a member of the European Commission’s High-Level Roundtable Expert group on the implementation of the Chemical Strategy for Sustainbility. She has been a member of ECHA’s Management Board (nominated by the European Parliament) and she has served as an expert for the Swedish Government on the issue of pharmaceuticals in the environment, and as a special inquirer for mixture risk assessment and grouping of chemicals.
Combined exposure to multiple chemicals: assessing risks across regulatory silosSee more
22/06 - 14:00Visit the agenda
Title of talk
The mixture assessment factor and the underlying principles
22/06 - 15:05
Abstract of talk
The science behind the (eco)toxicity of mixtures is clear: the total risk of a chemical mixture typically exceeds the risk of each individual chemical. Managing mixture risks is therefore needed to ensure a high-level protection for human health and the environmental.
Currently REACH chemicals are risk assessed one by one. Basically, assuming that each chemical is emitted into its own pristine environment. Also ignoring the likely simultaneous exposures to pesticides, pharmaceuticals, biocides and non-intentionally produced chemicals. As a consequence, current risk evaluations are systematically underestimating the real-world risks for humans and the environment.
There are different approaches to managing mixture risks. However, missing or insufficient data on toxicities, production volumes, use patterns, emissions and exposures constitutes a serious bottleneck for performing risk assessments or predictive modelling of mixtures. This makes a default scenario by means of a mixture allocation factor (MAF) a rational alternative.
Risk management should ensure that an individual chemical does not occupy more than a certain percentage (i.e. the allocation factor) of the maximum regulatory acceptable concentration. Introducing a MAF hence means that the assumed ‘safe’ exposure levels for single substances are divided by a factor, so that each individual chemical is only allowed to use a proportion of the tolerable exposure level. An exceedance of this level should either initiate refined assessments beyond the default scenario or prompt a systematic search for less risky alternatives (substitution).
A MAF will reduce the total chemical exposure, and it can be applied within the system for single chemicals.