Since the first fully synthetic plastic was invented in 1907, humans have found innumerable uses for the material. It has found its way into our tools, our clothes—and even our bodies. In a new study in Environmental Science & Technology, researchers estimate the average American eats more than 50,000 pieces of microplastic—fragments smaller than 5 millimeters in length—every year and inhales another 50,000. Although the health effects of consuming these microscopic bits of plastic are unclear, researchers stress the sheer volume that people are inadvertently swallowing is alarming. The largest contributor came from drinking bottled water, in which the bottle itself added more than 32 times more plastic to a diet compared with tap water, The Guardian reports.