Every day, we are typically exposed to numerous natural and man-made chemical substances. For example, our engagement in basic everyday activities such as breathing and eating exposes us to chemical substances. The European chemical policy and risk management schemes have predominantly focused on the safety of individual chemical substances. These efforts aim to protect public health and the environment by ensuring that no chemical substance is present in the environment at levels that might cause harm.
Recent reports have suggested that when chemical substances, both natural and man-made, are combined together (termed the combination effect) they might cause adverse effects to human health and the environment, even if the individual chemical substances (i.e. natural and man-made) are harmless. Although there is currently no evidence of such a “combination effect” from typical environmental substance levels, it is critical that we consider the possibility of harm.
Therefore, the chemical industry is engaged with European and international bodies and agencies to address this concern. Their collaborative efforts have revealed that, while it is always true that further research could provide additional insights into such a complex issue, there are now procedures and tools which can be applied to address the potential combination effects of chemical substances.
Approaches and tools to address potential combination effects of chemicals
Current research from industry, academic (including the European Commission Scientific Committees) and government sources indicates that the observed effects of combined chemical substances (i.e., at high concentration levels) in the laboratory are extremely unlikely to occur at ambient concentrations in the environment. In the rare instance when they do occur, it is unlikely to be toxicologically significant. Furthermore, current scientific evidence shows that when combined chemical exposure pose a risk, the risk is typically driven by one or just a few of the chemicals within the combination. As a result, controlling individual chemical substances through the current regulatory schemes will control the risk from such combination exposure.
Due to the complexity of our societies, it would be impossible to even imagine all the combinations of natural and man-made chemical substances in all possible concentrations which could arise in an environment: let alone to assess them all. It is therefore essential to develop screening criteria and tools, such as our newly-developed MCR screening tool, to prioritise the chemical combinations to be studied and to identify so-called “combinations of concern”.
As part of our commitment to ensure the safety of our products, the chemical industry is working with academia and government to develop and share tools to assist in the risk assessment of individual substances as well as combinations of chemicals. In particular, Cefic has developed a “decision tree - watch the video (incorporating the MCR tool) for the evaluation of human and ecological effects from exposures to multiple chemicals from a single or multiple sources”, which builds on the risk assessment framework of the WHO and the European Scientific Committees.
We are convinced that tiered risk assessment approaches with an increasing refinement of hazard and exposure assessment through the different tiers will provide a structured approach for risk assessment of combination effects where this is needed.
Cefic, through its Cefic Long-range Research Initiative, has successfully conducted proof-of-concept studies (of US and European surface water data and, of residential Indoor Air monitoring data from European studies), demonstrating the effectiveness of the decision tree tool.
The chemical industry will also contribute its expertise in the future investigations addressing the knowledge gaps in order to ensure that continued high protection levels are delivered towards our health and the environment.
Background information / documents
The Cefic expert group on combination effects has been providing scientific input into the discussions launched by the EU Scientific Committees and the relevant Commission services, European agencies and international bodies.