Our food, our water and the things we use every day are constantly contaminated by hundreds of harmful chemicals that build up in bodies and the environment.
Until about a decade ago, safety watchdogs only rated toxicity levels for each separate chemical on its own. They thought the effect of a build-up of many different chemicals at once was safe if each chemical in the mixture was within its own legal exposure limit.
Toxicologists at Brunel University London showed for the first time that even if each chemical in a mixture is at a safe level, the overall cocktail effect of the mixture is dangerous. But for years, chemical safety legislation stayed the same.
Mixtures of plasticiser chemicals (phthalates) found in everyday things like food wrappers, pesticides, toys, cleaning products and cosmetics are linked to male infertility. The finding helped trigger major moves in Europe-wide safety policy.
Pesticides, biocides, food contaminants and industrial chemicals are the most common types of harmful chemical mixtures people are exposed to in everyday life.
The 2020 EU Chemical Strategy for Sustainability pledged to fast-track risk assessments for pesticides and bring in new protective regulations for other chemical mixtures. This will protect 445 million Europeans from mixture risks. The European Chemicals Agency in 2017 used Brunel’s research to back restrictions on a group of four phthalates used in household goods, to protect 400,000 boys at risk from exposures.
In the last 10 years, the Brunel team, led by Dr Andreas Kortenkamp, published more than 30 scientific studies into the toxic effects of chemical mixtures. The resulting raft of evidence strongly suggests toxicologists can predict the effects of multi-chemical cocktails when they know how toxic each chemical in the mix is. In many different experiments with fish, rodents and cultured cells, the team accurately predicted mixture effects. Working with the European Food Safety Authority, the Brunel team put together a new workable way to group chemicals for mixtures risk assessment. The new approach brought in by the authority will influence maximum residue levels for toxic pesticides in food in Europe. It means people will be better protected against the extra risks of harm caused by a mix of pesticide residues found in most foods.
Key findings from this body of Brunel research are that a mixture of chemicals is usually more toxic than the most toxic chemical in the mix, and that mixtures of chemicals can still be dangerously toxic even if each chemical in it is at safe levels. Altogether, the toxicology team’s research shows that ignoring the effect of mixtures of chemicals underestimates the risk of toxicity.