Emily Penn has studied marine plastic pollution for years. Then she discovered the issue may disproportionately affect women, so she put together an all-female crew to research the issue. About 8 million tons of plastic waste enter oceans each year. These plastics break down into micro-plastics, which are mostly invisible to the naked eye. Over 5 trillion micro-plastics float on the surface of the ocean, and many more that have sunk below. Chemical pollutants bind to these plastics. Marine life mistakenly eat them, and they disperse into the food chain, including in the human body. "We chose 35 of these toxic chemicals that are banned. We found 29 of them in my body," said Penn. "They mimic our hormones and stop important chemical messages moving around our bodies. I realized that actually, being a woman, having those chemicals inside my body during a pregnancy would be really bad news." Her expedition was thus born, circumnavigating the earth to research plastic and toxin levels.