Readers Want to Know: Should we worry about microplastics in Lake Superior?
Answer: Microplastics, those pellet bits (<5mm in diameter) of synthetic dross that originate from broken down plastic beach litter or consumer face scrubs, are beginning to concern scientists and society. However, not enough information is known about their effects to conclude how much of a worry they should or could be.
In the summer of 2012, researchers discovered that the Great Lakes might be suffering from a unique case of microplastics. While on a mission to collect water samples in the Great Lakes, researchers were astonished to find tiny plastic particles suspended in the water. Although they knew about microplastics, what surprised the crew of the vessel was the size of the pellets (~1 mm in diameter). In a 2011 broadcast of The Sea Grant Files, Dr. Lorena Rios-Mendoza of the University of Wisconsin Superior, who studies these tiny pollution pieces in the Great Lakes, addressed the issue of litter that originates from larger pieces of plastic. These larger pieces of plastic are broken down into smaller and smaller fragments by weathering and abrasion.
Sarah Opfer, Great Lakes Regional Coordinator of the NOAA Marine Debris Program, adds, "Other potential sources of microplastics include industrial loss of pre-production plastic pellets as well as polyethylene bead exfoliants from personal care products."
Detecting polyethylene beads in the Great Lakes is a relatively new pursuit, so scientifically based conclusions can't be drawn yet. However, scientists are concerned that results from ocean studies on microplastics apply to the Great Lakes.
A common finding among ocean researchers, microplastics are troublesome because they can act as a sponge for other aquatic pollutants, such as polychlorinated biphenyls (PCBs), in addition the harm the plastic itself can cause when fish may mistake these particles for food. When the pieces are smaller, they also pose a greater risk because the toxin-collecting balls can be introduced lower in the food chain.
A review paper published in Great Britain indicates that when fish and other aquatic species mistakenly eat microplastics, health issues, damage to internal organs and a suspected transfer of toxins through the food chain may occur1. The review paper also suggested that toxins can be passed on for up to two generations. In a study on mussels, researchers found that microscopic plastic particles could move from the intestinal tract into the mussel's circulatory system2.
The lasting quality of plastics in seafood may affect people who eat them, too; in a review of studies pertaining to plastic objects in contact with food, scientists have found various reproductive problems associated with the introduction of plastics into the human body in general3. Again, however, a link between microplastics in aquatic systems and effect on human health is not scientifically proven.
Currently, Rios-Mendoza is examining microplastics in Lake Superior. She reports that Lake Superior is relatively clean, but she also notes that plastics are present, albeit in quantities too small to chemically analyze. She reports that her team has also examined 110 fish stomachs, finding plastic filaments in 20 (18%) of the samples4.
For now, there are a few things you can do to mitigate potential problems: if you use skin lotions and soaps, check the ingredients and choose products that do not include polyethylene beads. Some companies, like Burt's Bees and St. Ives use natural skin exfoliants such as crushed seeds from apricots and cocoa beans. Some companies are responding to the recent heat concerning their use of microplastics and are pulling merchandise from the shelf. And, as always, make sure to cleanup and recycle all plastics, especially when at the beach. This will reduce the amount of litter that can break down into microplastics in Lake Superior and the other Great Lakes.
Want more information on microplastics?
- The Great Pacific Garbage Patch (audio file)
- PBS's Almanac North microplastics segment on 8/2/13 (video file)
- NOAA's Marine Debris Program
1 Wright, S. L., Thompson, R. C., and Galloway, T. S. (2013). The physical impacts of microplastics on marine organisms: A review. Environmental Pollution 178: 483–492.
2 Browne, M. A., Dissanayake, A., Galloway, T. S., Lowe, D. M., and Thompson, R.C. (2008). Ingested microscopic plastic translocates to circulatory system of the mussel, Mytilus edulis (L.). Environmental Sci. Tech. American Chemical Society: Drake Circus, United Kingdom.
3 Thompson, R. C., Moore, C. J., vom Saal, F. S., Swan, S. H. (2009). Plastics, the environment and human health: Current consensus and future trends. Phil. Trans. R. Soc. B. 364(1526): 2153-2166.
4 Rios Mendoza, L. M., and Evans, C. Y. (2013). Plastics are invading not only the ocean but also the Great Lakes. American Chemical Society meeting, New Orleans.
By Russell Habermann