Plastic Excess

The world is flooding in plastic, and people should do their best to avoid using too much plastic, especially because a lot of it ends up in the sea. This is true. However, over-zealous anti-plastic campaigners are making claims that are not true; and these could eventually water down the anti-plastic message.  Let us examine some of these:

Small pieces of plastic go up the ocean food chain, and eventually get eaten by people, harming us.
It is important to point out that plastic particles are undigestible by animals of all sizes. This means that animal bodies do not allow plastic particles to pass from the digestive tract into the blood stream. The plastic remains in the intestines, and get ejected together with other undigestibles as feces.

Small pieces of plastic do indeed get eaten by sea creatures. The vast majority of these get excreted as feces and drops to the ocean bottom. If fish eat pieces that are too big to be excreted, they get stuck in their digestive tract. If these accumulate, they will eventually make the creature sick due to lack of nutrition; they then die and sink to the ocean bottom. Fish that eat smaller fish (who could have plastic particles in their digestive tracts) will also eject the plastic as feces.
The great majority of plastic particles eaten by fish end up at the ocean bottom, one way or another.

Fish that get caught for human consumption most likely have small particles of plastic in their digestive tracts. Before being eaten, however, the intestines and other internal organs are thrown away. In case people eat fish with their intestines, the plastic there will be ejected as feces.

Chewing gum is made up of synthetic rubber, which is a form of plastic.
This is wrong in a number of ways.  First, not all gum is made from synthetic rubber. Synthetic rubber is made from petroleum, and whose price depends on the oil price. When the oil price is high, synthetic rubber becomes expensive – too expensive to be used for gum.
Second, rubber is NOT plastic. Synthetic rubber is chemically the same as natural rubber. Like plastic, rubber is made up of long molecular chains. But, unlike with plastic, the molecular chains of rubber break apart naturally; they are biodegradable.

Plastic will be floating in the sea for thousands of years.
This inaccurate and deceiving. Individual pieces of plastic floating in the sea will be gone (i.e. sink to the ocean bottom) in less than ten years. Floating plastic attracts algae and other plants and animals to attach to them.  In a couple of years, they get heavy and sink to the bottom of the ocean.  The exception to this would be plastic that are extra buoyant, e.g. closed gerrycans, floats for fishnets, etc.  which may take longer than 10 years before they sink or get swallowed by a big fish or whale. But within decades, these too will be gone.
The problem is that the supply of new floating plastic is growing much faster than nature can get rid of them. If suddenly, the supply of floating plastic stops; all floating plastic will disappear in a few decades.

At current rates, there will be more plastic than fish in the oceans by 2050. 
This is the spectacular claim made by the Ellen MacArthur Foundation during the 2018 World Economic Forum. They extrapolated data from a study by Jenna Jambeck, which made projections till 2025.
The projection is slippery because it depends a lot on what we mean by ‘fish’.  If we are comparing the number of plastic particles (no matter how small) with bony creatures swimming in the ocean, plastic pieces will outnumber fish even now.  To be more objective, perhaps we should compare their total weight. And, we should also count all marine animals as ‘fish’ – from marine mammals, fish and squid, to clams, corals, krill, copepods and zooplankton.
The Ellen MacArthur Foundation uses the figure of 750 million tons of plastic in the sea by 2050 (Note that Jenna Jambeck does not agree with is extrapolation of her data.). Marine biologists estimate that total marine fauna is between 2 billion and 10.4 billion tons.  So, there will always be more fish than plastic, that is clear.

The 2050 claim does not consider the dynamic nature of the ocean. For one, there is a growing rate of plastic sinking to the ocean bottom, because of biological processes (narrated above). Of course, one can be philosophical in saying that the plastic is still in the ocean then; but we all know that what really counts is plastic that is floating in the ocean. Floating plastic promotes life that attaches to it, and flourishes around it, similarly to the effect of artificial corals; floating plastic has become part of the ecosystem.

The 2050 prediction does not consider the price of producing plastic. Plastic is a petroleum product, and the cost of producing plastic is a function of the price of oil. The current price of oil is slightly less than US$ 70 per barrel. In the future, the price will fluctuate, but will not go below the present price anymore. The reason for this is that cheap sources of oil are running out, leaving the more expensive sources. So, the price of oil will slowly increase; and by 2050, it will be significantly higher than it is today. This means that plastic will be significantly more expensive to make by that time.
More expensive plastic would mean that substitutes for plastic will become more available and relatively cheap. It also means that recycling plastic would make more commercial sense. As a result, plastic production will be reduced, and so will the runoff of plastic to the ocean.

Plastic in the ocean is mainly a problem for humans, not nature.  We are bothered by litter on the beaches and when we swim at sea. ‘Cute’ animals e.g. whales wash up onshore with plastic in their stomachs. Plastic will hinder our ships in various ways. Later, plastic will become a growing part of the catch by fishing vessels. And perhaps, most important, plastic floating in the ocean is an enormous waste of resources; if they are recycled, we would save having to use petroleum to make plastic.

Campaigns to lessen plastic production should emphasize real problems for humans that result from lots of plastic floating in the oceans.  They should also point out that plastic dumping is wasting valuable resources; and that recycling plastic saves resources and lessens the amount of greenhouse gas produced.