How should chemical mixtures be regulated?

The natural environment – our air, water and soil – hosts an ever-changing cocktail of synthetic compounds originating from a wide variety of sources. We are continuously exposed to a concoction of chemicals in our indoor environments too – from chemicals leaching out of carpets, furnishings and household objects, to those coming from foods, as well as cleaning and personal care products. 

It’s well established that exposure to chemical mixtures can cause harm – to the environment and human health – even if all the individual chemical components in the mixture are present at concentrations that would be safe if they were met alone. But the chemical industry is largely not expected to be very aware of potential issues with mixtures of its products. The majority of regulative frameworks set safe exposure levels for chemicals with the assumption that the chemicals are released into a pristine location (in either the body or the environment) where no other chemicals are present. But this is not the case. Regulations may well cover intentional mixtures of chemicals, such as those in detergent or paint formulations, but not those that occur coincidentally after their intended use.