The world is becoming clogged with plastic. Particles of plastic so tiny they cannot be seen with the naked eye have been found almost everywhere, from the oceans’ depths to the mountain tops. They are in the soil, in plants, in animals and they are inside us. The question is: what harm, if any, are they causing? When plastic trash is dumped in a landfill or the sea, it breaks down, very slowly. Sunlight and waves cause the surface of the plastic to become brittle, and particles are shed into the environment. Collectively known as “small plastic particles”, they range in size from five millime…