Microbeads are tiny, smooth, plastic spheres found in common household products such as facial soap. These beads, measuring from 0.0004 to 1.24 mm, roughly the size of some fi sh eggs, are too small to be removed by water treatment systems. Thus, they end up in rivers, lakes, and other bodies of water. The accumulation of these microbeads is an environmental concern for aquatic biologists because microbeads

a) make the lakes and rivers cloudy and dirty, affecting their appearance

b) may stick to some household water pipes, preventing drainage problems

c) could be mistaken for food by some species, working their way up the food chain

d) could clog fishing nets, affecting the ability of fishermen to catch fish