Why Microplastics Might Not Be Chemically Inert After All

Plastics are used everywhere partly because they are chemically inert: bags, food containers and cups don't react with what we put in them. But they still shed microplastics, which turn up in drinking water, human blood, arteries and brains — and the health consequences of that are uncertain. Wei Min, a chemist at Columbia University, puts it bluntly: whether microplastics can directly cause human disease is still being researched. In a new Nature study, Min's team took a step toward that question by showing microplastics are likely not as inert as we might expect. The mechanism is microdroplet chemistry. Min's lab studies how water broken into tiny droplets behaves at its boundary with air, and such droplets have been reported to generate reactive oxygen species — a family of harmful, oxygen-containing molecules. As Min describes the damage, ROS bump into proteins, lipids and DNA; they can break a DNA strand into segments, mutate DNA, or misfold proteins. The point is not that microplastics are proven to sicken anyone, but that the assumed inertness may be the wrong premise to build the safety case on.