The problem with very small plastic
APlastic waste used to be pictured as bottles on beaches and bags caught in trees. Scientists are now more concerned with fragments smaller than five millimetres, known as microplastics. Some are manufactured at that size, such as the beads once common in cosmetics; most, however, are produced when larger items break down under sunlight and waves, or when synthetic clothes shed fibres in the washing machine.
BMicroplastics have been found almost everywhere researchers have looked: in Arctic sea ice, deep-sea sediments, farm soils, drinking water and the air of large cities. Dr Amira Haddad, a marine chemist, notes that their small size allows them to be eaten by plankton, the tiny organisms at the base of ocean food chains, so particles can move upwards into fish and shellfish consumed by humans.
CWhat this means for human health remains uncertain. Professor Lars Eklund, a toxicologist, points out that most laboratory studies have used much higher concentrations than people are actually exposed to, and that the body excretes many particles. Others are less reassured. Dr Haddad argues that plastics can carry chemical additives and absorb pollutants from the water around them, so the particles may act as carriers for harmful substances even when the plastic itself is inert.
DPolicy responses so far have focused on the easiest targets. Several countries have banned microbeads in rinse-off cosmetics, and some are considering requiring filters on new washing machines. Economist Sofia Marques argues that such measures are useful but small, and that the only lasting solution is to reduce the total quantity of plastic produced, since every large item is a future source of microplastics.