There is a lot that we do not know when it comes to plastics and their impact on the environment, animals and humans. There is much that still needs to be learned before we can determine what needs to be done to better manage or eliminate this valuable modern resource. Far more scientific data must be collected, and research completed if we are to have a better understanding of plastics, micro-plastics, and nano-plastics and address issues arising from their use or misuse.
Mark Hahn of the Woods Hole Oceanographic Institute (WHOI) shared these insights during a talk sponsored by the Harwich Conservation Trust on Saturday, Feb. 8, at the community center. Dr. Hahn is a senior scientist in the biology department at WHOI and a project leader in the Boston University Superfund Research Program and the Woods Hole Center for Oceans and Human Health. He received his Ph.D. in environmental toxicology from the University of Rochester School of Medicine and Dentistry and was appointed to the scientific staff at WHOI in 1992. His current research focus is on the impact of micro-plastics in the environment. Hahn is the author or co-author of more than 160 papers in peer-reviewed journals and books.
“Micro-plastics, which are small pieces of plastic less than a quarter inch in diameter, have become the latest ocean pollutants to raise concern among scientists and the public,” according to the HCT announcement of the program. “Yet we still don't have answers to many of the most fundamental questions about these pollutants. What are the major sources of micro-plastics? Where do they go once they enter the ocean? How do they impact marine life? Are they a threat to human health? What is being or should be done about micro-plastics in the ocean?” WHOI's Marine Micro-plastics Initiative was created two years ago to help scientists “better understand and ultimately solve this global problem.”
Though some scientific information about plastics is known, there is a lot which is not, and that can lead to speculations and assumptions about the scope of problem or the nature of its solution, Hahn said.
“Globally over the past 65 years 8.3 billion megatons of plastic have been manufactured,” he said. “Much of it is still in use, a small amount has been recycled, incinerated or discarded, and roughly 1.5 million megatons are known to be in the oceans. Most of the plastic pollutants in the oceans result from mismanagement in China and Southeast Asia. There are five ‘plastic garbage patches’ worldwide, with the largest accumulations located in the waters off the West and East Coasts of the United States.”
While plastic has a long life expectancy, it is subject to degradation which in time reduces its size to measurable micro-plastics (0.33 mm to 5 mm in length) and nano-plastics (under 0.33 mm in length) which are too small to be caught in the nets that collect samples in the oceans. According to Hahn, scientists believe that the number of nano-plastics exceeds exponentially that recorded for micro-plastics, resulting in 99 percent of the plastics in the oceans being unavailable for measurement.
Hahn made a point of reminding the audience that plastic is a useful tool in modern society, and that pollution mostly results more from the mismanagement of their waste products than from their use. Among other things, plastics serve as strong and light-weight packaging and are used in many medical supplies.
“They are not going away,” Hahn says, “but they need to be better managed.”
Though studies have been done to determine, for instance, the amount of micro-plastics in various elements such as bottled water, air, beer, tap water, seafood, sugar, salt, and honey—and the possibility exists that some may contain toxic material—definitive and fundamental scientific research has yet to be done to determine any potential health risk posed for animals and humans. In one study cited by Hahn, a meal consisting of mussels was cooked and served to determine the level of nano-plastics in the seafood. At the same time the nano-plastics in the air next to the stove and on the dinner table were also measured. The results showed that more nano-plastics were consumed by those present through breathing the air than by eating the mussels.
While Hahn acknowledged the potential for harmful environmental or health effects from micro- and nano-plastics, his focus was more on the importance of better management of plastic and its waste. He cited especially the need for tire treads to be designed and manufactured in ways that lessen the nano-plastics they add to the atmosphere. Though he mentioned the current value of plastics, he did not address specific strategies for managing their waste disposal. Rather, Hahn believes scientists need to know with greater accuracy how much plastic is actually in the ocean and where it is located, what happens to plastic in the oceans, what its impact is on the environment, as well as animal and human health, and what and where are the greatest risk posed by plastics. His main message was to underscore the need for more scientific research and data in order to better understand plastics, micro-plastics, and nano-plastics, rather than to promote any strategy for addressing their potential negative effects.