Plastics and PCBs: Ocean Pollutants Causing Big Problems

Candice Gaukel Andrews August 27, 2019 0
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For centuries, people have used oceans as a food supply, a transport route and a convenient dumping ground—too vast to be affected by anything we do. But we may have finally pushed oceans to their limit.

More than eight million tons of plastic debris end up in our oceans every year. Present in nearly every oceanic layer, plastic garbage today accounts for nearly 80 percent of all waste found in our oceans. And some of the most insidious of it is microplastics (bits measuring 0.05–5 millimeters) and nanoplastics (smaller than 100 nanometers in size; in other words, 1,000 times smaller than an algal cell).

But plastics aren’t our only ocean woes. Long-lived polychlorinated biphenyls, or PCBs, could cause more than half of the world’s orca populations to collapse in 30 to 50 years.

By 2050, the World Economic Forum estimates that there could be more plastic in the oceans by weight than fish. And orcas across the northern hemisphere are among the most heavily contaminated animals on Earth. Luckily, however, there are some actions being taken—and ones we still can put into place—to alleviate the problem before it’s too late.

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Fertilizers, garbage, industrial chemicals, pesticides and plastics: most of the pollutants on land eventually make their way into the ocean.

The negatives of nano

Many plastics that end up in our oceans start out as large, floating items. Eventually, however, they break down into much smaller pieces. These particles (or microplastics) are eaten by beings at the bottom of the food chain; in fact, they’ve been found in the digestive tracts of more than 100 different species, posing chemical, biological and physical harm to these animals. But they also hurt us: ultimately, these plastic fragments find their way onto our dinner plates, into our sea salt and flowing out of our water taps.

In 2015, researchers at Lund University in Sweden investigated how nanosized, polystyrene plastic particles of different sizes affect aquatic animals in different parts of the food chain. It turned out that for the zooplankton Daphnia, 50-nanometer granules proved to be the most toxic.

Because zooplankton such as Daphnia are food for many other aquatic animals, the researchers followed the effects of the plastic materials up the food chain. They found that fish that ate Daphnia containing nanoplastics experienced poor appetites and changes in their predatory behavior. Researchers have also discovered that nanoparticles have the ability to cross biological barriers, such as the brain and the intestinal wall, and that the plastic morsels accumulate inside fish, which means that even low doses could ultimately have a negative effect.

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A 2015 study found that 90 percent of seabirds have ingested some plastic, mistaking it for food. If plastic consumption continues at its current rate, 99 percent of seabirds will carry plastic in their guts by 2050.

A matter of hours

Not only is plastic accumulation a problem, but just how quickly it happens in an organism is concerning. A groundbreaking study published in the journal Environmental Science and Technology in December 2018 shows that it takes just a matter of hours for billions of plastic nanoparticles to become embedded throughout the major organs of a marine organism.

The research, led by scientists from the University of Plymouth in England, examined the uptake of nanoparticles by a commercially important mollusk, the great scallop. After six hours of exposure in a laboratory, the scallops’ intestines contained billions of particles measuring 250 nanometers (about 0.00025 millimeters).

However, considerably more, even smaller particles—measuring 20 nanometers (0.00002 millimeters)—had become dispersed throughout the scallops’ bodies, including the gills, kidneys, muscles and other organs. Traces were still present several weeks later.

Killer whales are among the mammals with the highest levels of PCBs in their tissues. ©Eric Rock

It’s not only the plastics, but the PCBs

Plastics and nanoplastics aren’t the only dangerous pollutants now circulating in the world’s waters. Research published in September 2018 in the journal Science suggests that we stand to lose half of our planet’s orcas (Orcinus orca; also known as “killer whales”) in three to five decades due to lingering PCBs in the environment. These organic compounds were once used in capacitors, coolants and oil paints, until they were deemed so dangerous that their manufacture was banned in the U.S. and in other countries in the 1970s and 1980s.

While PCBs initially declined after the world stopped manufacturing them, in recent years levels of them in the environment have remained relatively constant. That’s because the compounds are still found in legacy products, such as cable insulation, transformers and some ship paints. In fact, 80 percent of global PCB stockpiles have not yet been destroyed.

Unfortunately, PCBs break down slowly and are drawn to the molecules of living animals, so they’ve worked their way into the food web, as well. Orcas are apex predators—they sit at the top of the food web. They eat fish, sea lions, seals, sharks and whales, and have no natural predators. So, carcinogens build up in their blubber.

Orcas are particularly threatened by PCBs in heavily contaminated areas. Around the British Isles, the remaining population is estimated at 10. Along Greenland’s east coast, the animals are affected due to the high consumption of sea mammals, such as seals. ©Wayne Hoggard, NOAA

Orcas range from Brazil to the Mediterranean Sea and from the Arctic to Antarctica. Unlike many land-based predators, such as polar bears, orcas have a hard time getting rid of PCBs. Their livers can’t metabolize them the same way that those of polar bears do; and orcas don’t make fur, which is an important excretion route of the compounds for the bears. Some killer whales now carry 25 times more PCBs than amounts shown to alter fertility. Mothers even pass the pollutants along during birth or through breast milk.

The authors of the September 2018 study found that 10 of the 19 orca populations they studied were already in decline, and that PCB exposure led to fewer animals over time.

For example, in the Pacific Northwest in Puget Sound, it’s thought that there were several hundred orcas during the 19th century. Today, that number is down to fewer than 80. From 2008 to 2014, nearly 70 percent of all known orca pregnancies there have failed.

While many factors contribute to this decline, three key ones have been identified: 1) a decrease in chinook salmon (which these southern resident orcas eat almost exclusively); 2) increased boat traffic noise, which makes echolocation difficult just as the orcas need to look farther afield for food; and 3) when whales are hungry and working hard, they metabolize fat, releasing PCBs and other toxic chemicals from their blubber into their bloodstreams. There the pollutants can damage the immune system, increasing disease risk. PCBs can act as neurotoxins, potentially disorienting whales, further complicating the hunt for food. And as starving whales get significantly smaller, the percentage of PCBs in their bodies increases, amplifying the impacts.

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After taking part in a video competition on ocean pollution, students said they were more concerned about the problem and were inspired to act on waste reduction.

Education encourages environmental action

Finding solutions for the growing amounts of ocean pollution is now widely recognized as one of the major environmental challenges of our time. Another recent study from the University of Plymouth offers some guidance on how we can address the issue.

To conduct this study, researchers enrolled 120 educators from 18 countries across Europe in an online training course about marine litter, asking them to complete a series of assessments to ascertain how it changed their attitudes. The results showed that the educators had high intentions of implementing the materials in their teaching and planned to encourage others in their network, which could lead to the training and resources being distributed more widely.

The scientists also invited 341 students aged seven to 18 from 12 European countries to take part in a video competition through which they were encouraged to make a two-minute film on the problem’s potential sources, impacts and solutions.

After taking part, the students were inspired to act; they said they were more concerned about the problem and perceived greater negative impacts and causes. They also reported that they engaged in more waste reduction behaviors, themselves.

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According to WWF, the largest living space on Earth is fast deteriorating. Our oceans are being overfished, taken for granted and carelessly abused. Will we change our habits before it’s too late?

Scrubbing the surfaces

A new device offers additional hope. In harbors, marinas and ports around the world, more than 700 instruments, called Seabins, are working around-the-clock, collecting fuel, plastics, microplastics and oil from the surface of the water.

The Seabin’s manufacturer states that one of the machines is capable of catching the equivalent of 90,000 shopping bags or nearly 170,000 plastic utensils over the course of a year. Each Seabin costs $4,500 and runs on either electricity or solar power.

Knowing the role that educators can clearly play, inventing devices such as the Seabin, and enacting national and international laws such as the one banning PCBs have all helped to ensure that future generations will live in a world without the threat of plastic pollution. But, in the end, it may be how strong our love of clean water and the oceans is that determines whether we can turn the tide.

Here’s to finding your true places and natural habitats,

Candy

If you’d like to join the fight, you can send a message asking government leaders to establish a global, legally-binding agreement to stop plastics from leaking into our oceans on World Wildlife Fund’s (WWF) website. Click here.

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