When you hear the word “microfiber,” you probably think of the now-ubiquitous reusable cloths used for cleaning floors, wiping up spills and polishing countertops. For environmentalists, however, that word has a much more sinister meaning. It describes the tiny threads that textiles — clothes, bedding, towels and, yes, reusable cleaning cloths — shed by the millions during each spin through the washing machine and which ultimately end up polluting the environment, particularly oceans, rivers and lakes. Since most clothing is made with synthetic materials, such as polyester and acrylic, it means that most microfibers are also microplastics.