This tray has a half-life in water of at least two years. The plastic bag, exposed to sunlight, has a half-life of more than five years. (Photo by Lisa Sorg)
By Lisa Sorg
(VM) – If the plastic food container that contained your lunch today winds up in a river, a local creek, or the Atlantic Ocean, 60 years from now people could find it, reasonably intact. The rest of the container will have degraded into micro-plastics — teeny particles that are visible only under a microscope. Fish or shrimp might have ingested those particles, filling their guts in place of food. People might have unknowingly drunk those plastic particles in water flowing from their taps.
Micro-plastics and their even smaller counterparts, nanoplastics, are a global environmental hazard. They pollute the oceans and rivers harming aquatic life, and potentially animals and humans. Yet these pollutants are understudied and in some cases, poorly understood.
Jack Kurki-Fox, a research associate at N.C. State University in Raleigh, North Carolina, sampled surface water at 15 stream gauges throughout the Neuse River Basin, established by the U.S. Geological Survey. Preliminary data show that 70% of the 6,100 samples taken in the basin were confirmed as containing plastic, Kurki-Fox said during a presentation at the NC Water Resources Research Institute last week.
Kurki-Fox and his colleagues had also collected “macro-plastics” from these waterways. These include tires, bags, beach balls, cups and bottles. These large items shed over time, creating micro-plastics. Using special analytical equipment, scientists found a filament that looked like cellophane; it came from the lining of a coffee cup.
Plastic waste by the numbers
- 22 million tons — estimated amount per year of plastic emissions worldwide by 2030
- 14 million tons — amount of micro-plastics that have settled globally on the sea floor
- 6.1 million tons — amount of micro-plastics generated by tire wear, annually
- 500,000 tons — amount generated by brake pad wear
- 58 years — average half-life in waterways of bottles made with HDPE, high-density polyethylene. (HDPE products have the recycling code No. 2.)
- 250 years — average half-life of HDPE bottles in landfills
- 1,200 years — half-life of HDPE pipes in waterways
- 5,000 years — half-life of HDPE pipes in landfills
Sources: Water Resources Institute presentation, ACS Chemistry & Engineering
To illustrate the lengthy lifespans of many plastics, researchers found plastics from a product known as Bakelite in the Neuse River Basin. One of the first plastics, Bakelite went on the market in 1908 and was discontinued in the 1940s.
Confounding matters, as plastics degrade — from exposure to sunlight, age, leaching, weathering — their chemical properties can change. They become harder to identify.
“We lack data and regulations on most of these,” said Susanne Brander, a scientist formerly at UNC Wilmington, who is now at Oregon State University. “Those chemicals don’t stay put. We can’t easily remove micro plastics from the environment.”
Most plastics are not recyclable. Only those labeled No. 1 and No. 2, and occasionally No. 5 should go in the recycling bin. The rest is disposed of in landfills. The United States and Europe used to ship a lot of their plastic trash to Asian countries, which no longer will accept the material. Wealthier nations, like the U.S. now foist their plastic on countries in Africa, where it is causing environmental and labor rights disasters.
Scientists and environmental advocates have known since the 1970s that plastics are a persistent, yet understudied pollutant with potential to wreak havoc on human health and the environment. Tens of thousands of substances are used in plastics. And the chemical properties of plastics change depending on weathering, age, exposure to sunlight, even the salinity of the water.
“We’re running out of time. People are tired of nothing being done,” said Bonnie Monteleone, a scientist and executive director of the Plastic Ocean Project, at the conference. “Nature doesn’t know what to do with these plastic particles.”
An estimated 14 million tons of micro-plastics globally have settled on the sea floor. The tiny plastic particles can also enter the air, for instance through sea spray, where people and animals can then inhale them.
“The ocean has been absorbing them for years and now they’re spitting them back at us,” Brander of Oregon State University said.
In saltwater, such as that along the coast or in the marshes, nanoplastics, the tiniest particles, tend to congeal, or cluster. Particles in saltwater also tend to float more than those in freshwater, where they often sink into the river bed.
Whether at sea or inland, aquatic lifeforms that consume these particles suffer. Monteleone and other researchers studied the responses of newly hatched fish larvae to micro-plastics. Those larvae with the greatest exposures spent more time near the sides of the containers — also called “the perimeter of anxiety.” (Like people who enjoy parties, fish larvae that congregate in the center of the container exhibit “boldness.”)
Fish larvae that consumed micro-plastics also grew more slowly. Scientists believe that one of the factors is that the foreign material takes up space in the gut, making the fish larvae less hungry. “They don’t get their full nutrition,” Monteleone said.
Exposure to micro-plastics also influenced how often and how long the fish larvae “froze” in place and the angles in which they turned.
These unusual behaviors are important because they show how the larvae interacted with their environment. The signs of stress and their reluctance to move make the larvae prone to predators. This upends the cycle of the ecosystem, ultimately all the way up the food chain to people.
People created the problem and now it’s incumbent on people to figure out the solution. Given our dependence on plastics — in bags, packaging, straws, cutlery, clothing, toothbrushes, tires, even the lining of coffee cups — “we need immediate solutions to these ubiquitous and unrecyclable materials,” Monteleone said. Install a filter on your washing machine to capture polyester and other plastic particles in clothing. Buy and use less plastic, in the spirit of a “circular economy.” If you must buy new plastic items, do so only if they are coded No. 1 or No. 2., or purchase goods made from recycled plastic. “Every time we pull a piece of plastic off the shelf we’re adding to the problem,” Monteleone said. “We need to get serious about a solution.”