Allan Maynard, MSc. November 23rd, 2020
Note – I realize these articles can be unsettling to read especially at a time when we may be looking for more uplifting news. However as a friend noted – the first step in solving a problem is addressing it. I feel obliged to do my small part towards increasing awareness of environmental issues and the need for science based decision- making.
Images of common household waste swirling in vast garbage patches in the open ocean or tangled up with dolphins, turtles and seabirds have turned plastic pollution into one of the most widely reported environmental issues of our day. However, what scientists can see and measure accounts for only a fraction of the plastic waste entering the environment. A consideration of tiny plastic fibers may not tug at the heartstrings like a picture of a sea turtle caught in a plastic pop ring, but these tiny particles and fibers are an even greater threat to our planet and consequently, human health.
As an emerging field of study, not a lot is known about micro-plastics and their impacts. The first inkling that plastic pollution is not limited to the plastic bags, soft drink bottles and other visible trash came in the 1960s and 1970s. During a research cruise to the Sargasso Sea in the Fall 1971 a marine biologist noticed peculiar white specks floating amidst the mats of brown seaweed. After some investigating he discovered they were tiny bits of plastic. It was a stunning discovery given the fact that thousands of the broken down particles were showing up in in the middle of the Atlantic Ocean. Ed Carpenter, now at San Francisco State University, published his observations March 17, 1972, in Science.
An explosion of research to track micro-plastics is revealing a mountain of plastic hidden not only in the oceans but in the world’s rivers, lakes, soils, as well as organisms big and small. Micro-plastics have also been found in the atmosphere and are thus transported around the globe. A seminal study was conducted in 2004 by a marine biologist at the University of Plymouth. Dr. Richard Thompson (who helped coin the term micro-plastic) found beach and coastal sediments off Plymouth, England, teeming with micro-plastics. Scientists around the world really sat up and took notice. Since then, studies have documented microfibers and fragments drifting around every ocean basin, in the bellies of marine species, and even frozen in Arctic sea ice.
WHAT ARE MICROPLASTICS?
Two classifications of micro-plastics currently exist. Primary micro-plastics are plastic fragments or particles that are already 5.0 mm in size or less before entering the environment. These include microfibers from clothing, micro-beads used as exfoliates in personal care products, and plastic pellets. Secondary micro-plastics are micro-plastics that are created from the degradation of larger plastic products once they enter the environment. Such sources of secondary micro-plastics include single use plastics, water and soda bottles, fishing nets, and more. Both types of micro-plastics are recognized to persist in the environment at high levels although it is likely that secondary micro-plastics are more abundant.
Size matters in the definition. Generally, micro-plastics are defined as less than 5 millimeters (mm). The range of 5 mm (size of a grain of rice) down to 1 mm (size of a pin head) is considered ‘large’ in comparison to an abundance of even smaller particles (less then 0.3mm). An even newer definition comes from the discovery of even smaller particles now called nano-plastics (1 to 999 nanometers). The smaller end range would be the size of a virus. In other words these particles are invisible without the aid of powerful microscopy.
Size also matters in terms of the detection of micro-plastics in the environment. Many of the earlier studies counted particles that were either visible to the naked eye or easily detected with standard microscopy. However the early studies were concluding that only a small percentage of the ‘missing plastic’ could be accounted for. To investigate further Melanie Bergmann, a marine ecologist with the Alfred Wegener Institute for Polar and Marine Research (AWI) led a comprehensive study in the Arctic. This study revealed 100 to 1,000 times as many micro-plastic particles frozen in Arctic sea ice compared to earlier studies. Two thirds of what the team found, using analytic instruments that read the chemical signature of plastics, was around 11 micrometers in diameter (about the size of a human red blood cell). Such sized particles were significantly lower than the detection limit of earlier studies. In fact, now it is speculated that some particles are so small that they more resemble a chemical actually dissolved in water.
ENVIRONMENTAL AND HEALTH IMPACTS
We are only beginning to understand the significance of the environmental and health impacts from micro- and nano-plastic particles. Firstly, it’s widely known that a broad range of species, ingest the particles. To date, micro-plastics have been found in over 100 different aquatic species. This does indeed make sense as the small particles resemble food for smaller aquatic species such as plankton, bivalves and small fish.
Since the topic of micro-plastics is still an emerging field of study, many of the effects of the micro-plastics on fish health are still unknown. However, several recent lab studies have shown a link between the ingestion of microplastics with stunted growth rates, reduced appetites, and the potential for reduced reproduction rates. These studies have also shown a correlation between the ingestion of microplastics by larval fish and an increased mortality rate among those fish as a result of the plastic getting stuck and blocking the fish’s digestive tract.
For human populations, even less is known. If the plastic particles remain in the digestive track of fish, it is likely that they would not become part of the human diet. However, smaller fish such as sardines and anchovies are often eaten whole – thus the possibility of human consumption would then occur. Bivalves such as clams and oysters are filter feeders. If exposed to micro-plastics they would accumulate the plastic fibers, which would in turn result in human consumption since bivalves are eaten whole.
Small plastic particles can also absorb other toxic chemicals that may exist in some ecosystems. Like a miniscule Trojan horse, the particles can then ferry in hazardous chemicals and help them accumulate up the food chain.
Perhaps an even greater threat is the airborne particles as they can be inhaled like any other air pollutant. The first study to measure plastic fallout from the atmosphere was published only in 2015. The recent attention to the issue means that there are only a handful of measurements of airborne plastic, and little sense of how the numbers might vary from place to place, depending on weather conditions and where the material is ultimately coming from. Alarmingly, there is growing concern about nano-plastics that are so small they can possibly enter cells and move into tissues and organs. Currently the ability to detect these particles in food and blood samples, etc. does not exist.
The research to date marks the first wave in what is likely to be a flood of such studies in the coming years, directed towards an effort to fill in the picture of how micro-plastics and nano-plastics move around the environment, affect wildlife and affect human health. This research will hopefully lead to increased regulations concerning plastic manufacturing and use. One example – On December 28, 2015, President Obama signed an Act (Microbead-Free Waters Act) banning plastic micro-beads in cosmetics and personal care products. This was long overdue and their use as exfoliates should never have been allowed in the first place.
It is obvious the plastics industry and our dependence on the products requires a comprehensive review that will lead to effective regulations, extensive research, and societal awareness. Such topics will be covered in an upcoming article.
Earth Has a Hidden Plastic Problem—Scientists Are Hunting It Down, A Thompson, Scientific American, August, 2018
Microplastics Are Blowing in the Wind, A Thompson, Scientific American, April 2015
(2018, June). What are microplastics?. Retrieved from
What Are Microplastics?. Retrieved from https://www.greenmatters.com/t/microplastics