Oceans in Crisis - Ocean Worlds: The Story of Seas on Earth and Other Planets - page 172

Angels' tears, the snorkelers and scuba divers call them—the deli-
cate translucent scraps adding their own unsettling kind of beauty to
the age-old patterns of fish and medusae, arrow-worms and lengths
of seaweed. Are they, though, merely a highly visible but harmless
addition made by humans to the natural world? Plastics, after all, are
relatively inert (which is why they take so long to break down) and are
designed to minimize toxicity. One can drink from a polystyrene cup
without worrying about being poisoned by it.
Escapees from the human realm, the plastic can, at times, be any-
thing but benign. Among the victims are the seabirds, seals, and tur-
tles choked by plastic fragments or starved to death because their
stomachs are full of an indigestible mass of human junk. Similarly,
tiny, submillimetre-sized plastic fragments can be captured by filter-
feeding plankton. Filter-feeders, large and small, are particularly vul-
nerable. They are unselective by nature, simply sweeping up suitably
sized particles out of the water. If most of the particles in a water mass
are made of plastic, then most of the food supply of a filter-feeding
animal will therefore be of plastic too.
The dangers might reach down to tinier levels. Plastics are not
quite inert. For a start, in the manufacturing process not all the indi-
vidual chemical units—monomers—will react together to produce
the polymer chains of the plastic, and these trapped, unreacted mon-
omers are not chemically inert. Then, to make plastics more plastic-
like —to make clingfilm cling, for instance—plasticizers can be added.
In addition, certain plastics tend to absorb hazardous chemicals—
polychlorinated biphenyls (PCBs), for example. Such plastic frag-
ments can act as sources of slow-release toxins to the animals and
birds that eat them.
These dangers, actual and potential, have led to calls for plastic
waste to be classed as chemically hazardous (a status it does not enjoy
at the moment), in the hope that it may help control the spread of