In its first report on the issue, the WHO found that larger particles, and most smaller ones, pass through the body without being absorbed. But it said the findings were based on "limited information" as it called for greater research on the issue. "We urgently need to know more", the United Nations body said.
The WHO's Dr Bruce Gordon committed to launching the review while speaking to BBC News last year, after Orb Media found plastic particles in many major brands of bottled water. Microplastics, defined as small (less than 5mm in length) pieces of any kind of plastic debris, have been found in rivers, lakes, drinking water supplies, and in bottled water.