Plastic litter poses a special threat to the world’s oceans.
Roughly 40% of the plastic produced each year is disposable, and much of it is packaging that is only used for minutes before being discarded (Source). Because of a lack of proper waste disposal and recycling systems globally, most of this plastic waste becomes litter. In fact, the vast majority of the ocean’s litter (80%) begins on land, and 60-90% of this litter is plastic waste (Source).
Once in the ocean, floating plastic concentrates in giant garbage patches, created by circular patterns of currents in the world's oceans. The Great Pacific Garbage Patch is estimated to contain 1.8 trillion plastic pieces, equivalent to 250 pieces of debris for every person on the planet (Source). This plastic does not go away, but continues to affect marine life as physically dangerous material and toxic substances.
Threats to marine life
According to the National Oceanographic and Atmospheric Administration, plastic debris kills an estimated 100,000 marine mammals annually, as well as millions of birds and fish (Source). Plastic litter can be a physical danger to wildlife that becomes entangled in plastic debris like plastic bags, or when wildlife consumes plastic items like bottle caps.
Even more challenging is the plastic waste we cannot see. The physical actions of sun, wind, and water also plastic into tiny pieces, known as microplastics, that are not visible to the naked eye. Marine birds, fish, and sea turtles then mistake these microplastics for plankton or other native prey. This plastic diet poses an ongoing threat due to its toxicity and because it gives wildlife a false sense of fullness, ultimately resulting in starvation.
Toxicity in the food chain
In the marine environment, plastic absorbs persistent organic pollutants and becomes increasingly toxic over time. Plastic packaging contain a wide range of additives, such as water repellents, flame retardants, stiffeners like bisphenol A (BPA), and softeners called phthalates that can leach into the surroundings (Source). These chemicals concentrate in marine food chains, and are then stored in the fatty tissues of the creatures that consume them. Toxins continue to bioaccumulate up the food chain, increasing in concentration with each predator. While microplastics haven't yet been found in seafood, scientists are concerned about the human-health impacts of marine plastics (Source). As microplastics continue to fragment into even-smaller nanoplastics, they can penetrate cells and move into the tissues and organs of fish.
To begin solving the problems of marine litter, we need to quickly move away from disposable petroleum-based plastics. Individuals, organizations, governments, and communities can pledge to eliminate single-use plastics and use reusable or compostable alternatives.
See a running list of action on plastic pollution on National Geographic's website.