Small tire particles inhibited growth and caused adverse behavioral changes in organisms found in freshwater and coastal estuary ecosystems, according to two new studies from Oregon State University.
The findings are part of an ongoing effort by scientists to unravel the impacts of microplastics and nanoplastics on aquatic ecosystems and aquatic organisms. Tire particles are one of the most common types of microplastics in aquatic ecosystems.
Stacey Harper, Susanne Brander, and several graduate students and postdoctoral researchers in their labs, including Brittany Cunningham, Samreen Siddiqui, recently published two articles on tire particle research in Chemosphere and the Journal of Hazardous Materials.
“The focus on microplastics and now nanoplastics is still relatively new,” saidharpist, an Oregon State professor who studies the impacts of nanomaterials on environmental health and safety and has led research on tire particles in freshwater organisms. “We are now on the verge of making political decisions for which we do not have the science. That’s why we strive to provide this science.
California is at the forefront of this problem, with anational microplastics strategyadopted last week. Similar efforts at the federal level and potentially among other states are expected, saidMarker penassistant professor and ecotoxicologist at Oregon State who led the Coastal Tire Particle Study and also served as co-chair of one of the many scientific advisory teams that helped shape the California strategy.
Tire particles are made up of materials such as synthetic rubber, fillers, oils and other additives. The particles themselves and the chemicals they release, called leachate, can have adverse effects on aquatic organisms they come into contact with, the researchers note.
The researchers cite studies that show that over the life of an automotive tire, approximately 30% of its tread erodes and enters the environment. They also cite arecent studywhich estimates that more than 1.5 million metric tons of tire wear particles enter the environment each year in the United States.
“I think especially with tire particles that everyone measures how many there are, but very few groups measure the impact they have,” Brander said. “That’s really the gap we were trying to fill here.”
To do this, Oregon State scientists exposed two model organisms in freshwater and estuarine ecosystems to varying concentrations of micro and nano tire particles and leachate created by the decomposition of tire particles. tires. Microparticles are fragments less than 5 millimeters (0.20 inches) in length. Nanoparticles are so small that they cannot be seen with the naked eye or under a simple microscope.
In theestuary ecosystem paper, led by postdoctoral researcher Samreen Siddiqui, the model organisms were the inner silverside and the mysid shrimp. The researchers’ findings included:
- Both organisms, upon exposure, had significantly altered swimming behaviors at environmentally detected concentrations, such as increased freezing, changes in positioning, and total distance traveled, which the researchers believe could result in increased risk of predation and challenges for organisms to find food in the wild.
- Both organisms had reduced growth depending on the level of exposure to tire microparticles. Fish exposed to tire nanoparticles also had reduced growth.
- Leachate affected behavior but had no impact on the growth of either organism.
These findings led the researchers to conclude that even at current environmental levels of tire pollution, which are expected to increase, aquatic ecosystems could be negatively impacted.
In thefreshwater ecosystem paper, led by graduate student Brittany Cunningham, embryonic zebrafish and crustacean Daphnia magna were the model organisms. Among the discoveries:
- Both organisms suffered mortality and developmental abnormalities due to exposure to tire particles and leachate.
- Tire particle leachate was the primary toxicity factor for both organisms.
- Exposure to tire nanoparticles increased toxicity compared to leachate alone.
These findings led the researchers to conclude that while tire particle toxicity was observed in both organisms, the overall sensitivity to tire particles differed. They believe it is important to understand these differences to identify the levels at which these pollutants become toxic. This knowledge, they note, is crucial for creating risk assessments, which inform policy decisions.
The researchers also mentioned several ways to limit the ingress of tire particles into the environment. These include installationrain gardenson roadsides to capture tire particles, install particle capture devices on cars, develop tires that last longer, and invest in green infrastructure, like public transit, that allows people to drive less .
The research is supported by aNational Science Foundation Big Idea Growing Convergence Research Grant. Grant supports the State of OregonPacific Northwest Plastics Consortiumwhich Harper and Brander co-direct.
Harper and Brander are based at the Oregon State College of Agricultural Sciences. Harper also has a post at the College of Engineering. Other co-authors of the articles include Bryan Harper, Sarah Hutton, John Dickens and Emily Pedersen.