Plastic pollution on the Great Lakes can take many forms. Larger discarded plastics like bags, bottles, and packing materials eventually break down into tiny pieces or fragments. These “microplastics” are found alongside small fibers from synthetic clothing and microbeads from personal care products.

Another type of microplastic comes directly from plastic manufacturing: pre-production pellets or “nurdles” that are used to create most plastic products. The pellets are often accidentally dumped into the environment in large quantities during transport, after which they can release or “leach” chemicals into the water.

The capacity for these chemicals to impact ecosystems in the Great Lakes is the subject of a newly funded Ohio Sea Grant research. Led by Dr. Christopher Ward, assistant professor of microbiome ecology at Bowling Green State University, the project will study the toxic effects of plastic leachates on several levels of the food chain in Lake Erie.

“Our waters are a crucial drinking water source, a highly productive fishery, and home of diverse wildlife,” Ward said. “We need to know how plastic pollution may endanger our freshwater resources.”

Pre-production pellets contain raw resin and are transported to plastic molding facilities, where they are melted down and shaped into the consumer products that we use, Ward said. Frequently, these nurdles will spill into the environment, posing risks to aquatic ecosystems.

The pellets can contain hundreds of different chemicals that manufacturers add to determine the plastic’s flexibility, durability, or color. However, these additives can dissolve and migrate out of the plastic when submerged in water through a process called leaching, Ward said. Leachates, meanwhile, refer to water that has accumulated these chemicals.

“Since pre-production pellets are brand-new, they contain a lot of chemicals that can leach out and potentially harm aquatic organisms,” he said.

The research got its start nearly a decade ago at Duke University Marine Lab on the coast of North Carolina, where Ward did his graduate work. There, Dr. Dan Rittschof and members of his lab measured the toxicity of plastic leachates using barnacle larvae as test organisms. Notably, most studies on plastic toxicity have been conducted in marine systems with marine organisms, while freshwater systems receive less attention, Ward said.

“Once I moved to BGSU and became immersed in the Great Lakes and freshwater ecology, I realized the knowledge gaps that exist,” Ward said. “There are fundamental differences in how chemicals behave in freshwater versus saltwater, so we can’t assume that marine studies are totally transferrable to freshwater.”

With the new project, Ward and his team plan to assess the toxic effects of leachates from commonly used plastic types on Lake Erie microbial communities, phytoplankton, and zooplankton using a combination of experiments in the field and in the lab. Researchers also hope to identify leachate components and determine whether they’re present in the lake and in drinking water.

Through toxicity bioassays, the team will use plastic leachates generated by incubation in filtered lake water to test the effects on aquatic organisms. Ward will work with Bowling Green’s Dr. James Metcalf, an ecotoxicologist with expertise in analytical chemistry, to link the leachates’ chemical compositions to the biological effects observed in experiments.

“Right now, we’re in the very early stages, but so far we’ve been spending time figuring out how to reconfigure our standard procedures,” Ward said. “Just as in our everyday lives, plastic products are ubiquitous in the lab, and we need to replace plastic bottles, tubes, etc. to avoid plastic leachate contamination in these experiments.”

The project is set to end in 2026, and Ward said he hopes the work results in collaboration among other groups at universities, government agencies, and nonprofits that are filling knowledge gaps about plastic pollution.

“We will be looking at whether plastic leachate chemicals are found in drinking water, both tap and bottled water,” Ward said. “Several studies have shown that bottled water contains more microplastics than tap water. What about leachate? I think that’s information that many people are interested to know.”

For more information about this newly funded research project, contact Dr. Ward at chrward@bgsu.edu.

Ohio Sea Grant is supported by The Ohio State University College of Food, Agricultural, and Environmental Sciences (CFAES) School of Environment and Natural Resources, Ohio State University Extension, and NOAA Sea Grant, a network of 34 Sea Grant programs nation-wide dedicated to the protection and sustainable use of marine and Great Lakes resources. Stone Laboratory is Ohio State’s island campus on Lake Erie and is the research, education, and outreach facility of Ohio Sea Grant and part of CFAES School of Environment and Natural Resources.