We have long known about massive piles of garbage that blot the surface of the oceans. The Great Pacific Garbage Patch is a sprawling 1.6 million square km mass floating between Hawaii and California that is estimated to contain about 1.8 trillion pieces of plastic — or about 250 pieces per person on the planet — and weighs about 80,000 metric tons. A similar patch stains the Atlantic Ocean.

Because plastic floats, scientists had assumed that those horrific spectacles were the worst of the problem. They recently discovered, however, that plastic can be found far below the ocean surface. In fact, most of the plastic is underwater, from just below the waves to the deepest parts of the ocean. Concentrations are higher the greater the distance from shore. Plastic fibers have even been found in the stomachs of creatures in the Marianas Trench, the lowest point on Earth at 12,000 meters below sea level. Japan is pressing for action in the Group of 20 to counter this discovery; it is long overdue.

Scientists have discovered that the highest concentrations of microplastics — tiny pieces of material less than 5 mm in size — are in water 200 to 600 meters deep and reach levels of 12 to 15 particles per square meter, amounts comparable to those of the Great Pacific Garbage Patch. They concluded that the presence of these plastics “extends much further and more extensively into the waters, sediments, and animal communities of the deep sea” than previously realized.

That has triggered alarm bells since the deep ocean is the world’s largest ecosystem, a giant food chain populated by animals in constant motion, moving up and down as well as huge distances across those waters. Most anything and everything in those waters is consumed and passed from one species to another.

This grim state of affairs is the result of 70 years of plastic manufacturing. It’s estimated that annual global primary plastic production is 270 million tons; annual plastic waste is 275 million tons. Scientists reckon that about 8.8 million tons of plastic enters the ocean annually. Forecasts show that the amount of plastic in the ocean could triple within 10 years, while the weight concentration will double by 2030 and again by 2060.

Plastics break down over time, but it can take hundreds of years. In many cases, they dissolve into microplastics, which never degrade. Most plastic discovered by researchers was polyethylene terephthalate (PET), which goes into single-use plastics, such as food packaging.

The health effects of this plastic plague are not yet clear. The plastic itself may not be problem; rather, there is concern that resins in the microplastics attract chemicals such as persistent organic pollutants — stable compounds resistant to chemical and biological degradation, such as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) — that attach to the plastics and are eaten by marine animals and passed up the food chain, eventually reaching humans. There is evidence that PCBs and PAHs cause neurological and hormonal damage, but no consensus on the potential harm.

Waters around Japan have a higher density of microplastics than the global average, with one study of 29 rivers in the country revealing that every river contained microplastics. The highest density occurred around highly populated areas, proof that the pollutants originate on land and find their way to the sea. It is estimated that 90 percent of plastic in the oceans come from just 10 of the world’s rivers; this is an urban problem.

Japan is attacking on two fronts. In March, the government released the draft Strategy for Plastic Resources Circulation to prevent the release of microplastics into marine environments by 2020. It covers the reduction, reuse and recycling of plastics in general and aims to implement measures that stop the release of microplastics into marine environments and promote additional study of the problem. Current rules are voluntary and various industries are working to reduce their emissions. Plastic bans are increasingly popular, and last week Economy, Trade and Industry Minister Hiroshige Seko announced that it will become mandatory to charge for disposable plastic shopping bags as early as next April. Environment Minister Yoshiaki Harada announced a plan to introduce a uniform ban on free plastic shopping bags at supermarkets and other shops.

Those announcements were followed by agreement at the end of a G20 meeting over the weekend to establish an international framework to cooperate to reduce marine plastic waste. This follows criticism of Tokyo last year for refusing to sign, at the Group of Seven summit, the Ocean Plastics Charter which sought to make all plastics recyclable by 2030. The government argued then that more time was needed to stop this plague. Action must follow this year’s G20 leader’s meeting, not more studies that substitute for genuine remedial steps.

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