Many things we use on a daily basis contain microplastics. Very often they are found in clothing, cosmetics but even shampoo and toothpaste. These small plastics are not filtered out very well in our sewage systems so they end up in the ocean. Plankton and small fish mistake the microplastics for food and consume it. And guess who eats the plankton? Yes, the fish we eat (or hopefully you don’t!).
So we pollute the marine life and then we pollute ourselves. Manufacturers are slowly getting aware of this problem and hopefully they resolve it soon under pressure of the consumer and politics. But we can make a choice now in what we buy of course. There are many alternatives on the market and easy to find on the internet.