Cocktail effect

However, evidence for this theory is limited and the reality is that when we are exposed to a variety of chemicals at the same time, the result is much more likely to be simply additive. This is why The safety of cosmetic ingredients is mainly assessed one at a time, because it is important to understand the impact that individual ingredients may have and to ensure that they are only present in our products in safe amounts.

Scientists can and do investigate whether substances will have additive effects or synergistic effects or even cancel one another out when devising their formulations. These findings are taken into account when assessing the safety of a product. There can be circumstances where it is relevant to assess combinations of exposure to different substances in cosmetic products together; for example, because the compounds are from the same family and can act in very similar ways on our bodies. Therefore, the total exposure will be assessed to ensure that the finished product is safe.

Remember that even a simple cup of tea is in fact a cocktail of more than 200 chemicals, plus milk and sugar.

The European Food Safety Authority (EFSA) has a helpful infographic describing how any risks of chemical mixtures can be assessed.