In 2014, it was estimated that there was approximately 268,940 tons of plastic pollution in the world’s oceans. The litter that is being delivered into the oceans is toxic to marine life, and humans. The toxins that are components of plastic include diethylhexyl phthalate, which is a toxic carcinogen, as well as lead, cadmium, and mercury.
Plankton, fish, and ultimately the human race, through the food chain, ingest these highly toxic carcinogens and chemicals. Consuming the fish that contain these toxins can cause an increase in cancer, immune disorders, and birth defects.
There are three major forms of plastic that contribute to plastic pollution: microplastics, megaplastics and macroplastics. Mega- and microplastics have accumulated in highest densities in the Northern Hemisphere, concentrated around urban centers and water fronts. Plastic can be found off the coast of some islands because of currents carrying the debris. Both mega- and macro-plastics are found in packaging, footwear, and other domestic items that have been washed off of ships or discarded in landfills. Fishing-related items are more likely to be found around remote islands. These may also be referred to as micro-, meso-, and macro debris.
Plastic debris is categorized as either primary or secondary. Primary plastics are in their original form when collected. Examples of these would be bottle caps, cigarette butts, and microbeads. Secondary plastics, on the other hand, account for smaller plastics that have resulted from the degradation of primary plastics.
Microplastics or microdebris
Microplastics are plastic pieces between 2 mm and 5 mm in size. Plastic debris that starts off as meso- or macrodebris can become microdebris through degradation and collisions that break it down into smaller pieces. While they can be recycled to make new plastic items, they easily end up released into the environment during production because of their small size. Scrubbers that come from cleaning and cosmetic products are also microplastics. Because microplastics are so small in size, they often end up in ocean waters through rivers and streams. There, they are taken by the ocean currents and accumulate in large vortexes known as ocean gyres, where filter-feeding organisms consume them.
A 2004 study by Richard Thompson from the University of Plymouth, UK, found a great amount of microdebris on the beaches and waters in Europe, the Americas, Australia, Africa, and Antarctica. Thompson and his associates found that plastic pellets from both domestic and industrial sources were being broken down into much smaller plastic pieces, some having a diameter smaller than human hair. If not ingested, this microdebris floats instead of being absorbed into the marine environment. Thompson predicts there may be 300,000 plastic items/km2 of sea surface and 100,000 plastic particles/km2 of seabed.
Primary Microplastics, a type of microdebris known as Nurdles, enter the ocean by means of spills during transportation or from land based sources. These micro-plastics can accumulate in the oceans and allow for the accumulation of persistent bio-accumulating toxins such as DDT and PCB’s which are hydrophobic in nature and can cause adverse health affects.
Plastic debris is categorized as macrodebris when it is larger than 20 mm. These include items such as plastic grocery bags, straws and fishing nets. Macrodebris are often found in ocean waters, and can have a serious impact on the native organisms. Plastic bags often become ingested by turtles it for jellyfish, then they eventually die because their body is unable to process and remove the plastic. Fishing nets, even after they have been abandoned, continue to trap marine organisms and other plastic debris. Eventually, these abandoned nets become too difficult to remove from the water because they become too heavy, having grown in weight up to 6 tons. Marine mammals, from seals to whales, then become entangled in these nets and drown.