Where do plastic bottles and plastic grocery bags go to die when they’re discarded?
The better question might be, do they ever die?
Studies around the world have shown that many plastics break into small pieces, or microplastics, that persist indefinitely. They clutter the ocean – and the Great Lakes. The U.S. Geological Survey estimates there are 112,000 particles of plastic per square mile of Great Lakes water. And a sampling of Lake Ontario and Lake Superior fish found the “highest concentration of microplastics and other anthropogenic [human-made] microparticles ever reported in bony fish, including 12,442 anthropogenic microparticles in 212 fish from nearshore Lake Ontario, and 3094 in 119 fish from Lake Superior. 35-59% of the particles were microplastics.”
Plastic particles 5 millimeters (0.2 inch) or smaller are considered to be microplastics. Studies have found microplastics in the atmosphere, on land, and in oceans and freshwaters. They have also made their way into drinking water and foods intended for human consumption. And from there they enter the human body.
While the specific, causal effects plastics may have on human health are yet unknown and currently being researched, animal studies suggest that plastics and plastic byproducts affect digestive, respiratory, endocrine, reproductive, and immune systems. Plastics may act as both physical and chemical stressors to people, as they enter through the human digestive, respiratory and circulatory systems.
Another study attempted to estimate the global mean rate of human consumption of microplastics, producing a figure of 0.1–5 g of microplastics per week. Variability is high depending on location, age, size, and cultural factors. The high end is roughly equivalent to ingesting a credit card’s weight of different types of plastics every week.
Although we don’t yet know how microplastics affect human health, there are worrisome signals. Preventing human exposure to microplastics should be a priority. Finding substitutes for the microplastics that are intentionally added to agricultural chemicals, paints, cosmetics, and detergent, for example, is critical. For example, scientists are now piloting a system based on biodegradable silk instead.
There is hope – but there is also urgency.