Photo: Jens Lasthein
Christina Rudén, professor of toxicology at Stockholm University, has investigated how humans are exposed to complex mixtures of chemicals. Photo: Jens Lasthein

With the help of current legislation, concentrations of documented harmful chemicals have fallen in Europe, both in humans and in ecosystems. However, the use of other chemicals about which not so much is known has increased rapidly in recent decades. Today, a mixture of chemicals is found in virtually all samples taken from humans and the environment.

Emissions have shifted from high concentrations of individual chemicals to lower concentrations of a multitude of complex mixtures of different environmental toxins: a chemical cocktail. It is now known that the accumulated effect of such a cocktail frequently has a greater impact on us and nature than the effect of each single substance.

Proposals for action

The inquiry shows that major changes need to be made to the current chemical control system. In the report “Future chemical controls”, eleven proposals for action are recommended.

“To ensure a high level of protection for humans and the environment, coordinated action is required at different levels and within different parts of the regulatory system. It will take time and cost money and must be seen as a complement to everything else that is already being done today,” says Christina Rudén who has led the inquiry.

More relevant risk assessments

One part of the inquiry focuses on the cocktail effect and making more relevant risk assessments to protect human health and ecosystems. In practice, it is impossible to identify and test all imaginable chemical mixtures and therefore models are needed that can predict how toxic chemicals will be if they are mixed. Risk assessment methods do exist but more research is needed on the actual composition of the mixtures. In cases where there are no data, the inquiry recommends the assessment should be based on a standard scenario. Similar models are already being used for individual chemicals, for example, if risks for mice need to be “translated” into risks for humans. Christina Rudén proposes a new model for the assessment of chemical mixtures. The results are imprecise and not entirely reliable but the measure is relatively easy to implement and risks will be reduced immediately.

Handling groups of chemicals

The other part of the report focuses on groups of substances that have similar structure and characteristics. A chemical can be changed, given a new name and thereby no longer be classified as toxic, even though the effects may be the same as those of the original substance. This is something the investigators state needs to be changed. It must be easier for decisions to be made for entire groups of substances.
“A lot of work is already being done regarding the grouping of chemicals and this needs to be reinforced, clarified and communicated. A simple measure could be to put a warning flag on the chemicals that belong to the same group as other chemicals that are already documented as being harmful,” says Christina Rudén.

The inquiry’s proposals for action:

1.    Mandatory risk assessment of mixtures in all legislation on chemicals.
2.    New comprehensive European legislation on chemical environment and health risks, with a focus on mixtures.
3.    A new framework directive for health with the aim of protecting humans from both chemical and non-chemical environmental factors.
4.    Gather information on the use and release of chemicals in a central database.
5.    Research to increase knowledge about real exposure patterns for chemical mixtures.
6.    An allocation factor for the handling of risks posed by chemical mixtures.
7.    Mandatory application of the substitution principle in all relevant legislation.
8.    Stricter requirements for chemicals to be handled in groups in REACH.*
9.    Flagging of chemicals as suspected particularly hazardous substances in REACH* based on group assessment and read-across.
10.    More stringent requirements for risk assessment of mixtures and groups in the forthcoming revision of the Water Framework Directive.
11.    A new governmental working group for the risk assessment of mixtures.

The expert team that has investigated the matter

In March 2018, the government ordered an inquiry in order to take a holistic approach to the risks posed by chemical mixtures. Christina Rudén, professor at the Department of Environmental Science and Analytical Chemistry, Stockholm University was appointed as the special investigator. She brought together a team of experts consisting of Thomas Backhaus (professor, University of Gothenburg), Per Bergman (lawyer and former General Counsel at the Swedish Chemicals Agency), Dr Linda Molander (Public Health Agency), Dr Michael Faust (independent environmental consultant) and Dr Daniel Slunge (economist, University of Gothenburg). The investigators have also consulted a number of experts in Sweden and abroad, from different government agencies, industry, the academic community and various voluntary and environmental organisations.
* REACH is an EU regulation that entered into force on 1 June 2007. REACH was adopted to improve the protection of human health and the environment from risks that may be caused by chemicals, while at the same time increasing the competitiveness of the EU chemicals industry. REACH stands for registration, evaluation, authorisation and restriction of chemicals.