Tiny tire particles inhibit biological growth in freshwater, coastal estuaries, study finds

Small particles from tires inhibit the growth of organisms found in freshwater and coastal estuarine ecosystems and lead to adverse behavioral changes, OSU scientists have found in two new research papers

The findings are part of an ongoing effort by scientists to unravel the effects of microplastics and nanoplastics on aquatic ecosystems and aquatic life

Harper, Brand, and several other graduate students and a postdoctoral scholar in their labs, including Brittany Cunningham and Samreen Siddiqui, recently wrote in " Two papers on tire particle research have been published in Chemosphere and the Journal of Hazardous Materials

Oregon State University professor Stacey Harper has studied the impact of nanomaterials on environmental health and safety and led the study of tire particles in freshwater organisms

California is at the forefront of this issue, adopting a statewide microplastics strategy last week

Tire pellets consist of synthetic rubber, fillers, oils and other additives

The researchers cite studies that show that over the life of a car tire, about 30 percent of the tread will erode and enter the environment

"I especially feel like everyone is measuring the amount of tire particles, but very few organizations are measuring the impact they have," Brand said

To do this, OSU scientists exposed two model organisms in freshwater and estuarine ecosystems to varying concentrations of micro-nano tire particles and leachate from the decomposition of tire particles

In the estuarine ecosystem paper, led by postdoctoral scholar Samreen Siddiqui, the model organisms are inland silverfish and shrimp

• Both organisms, after being exposed, had significant changes in swimming behavior detected in environmental concentrations, such as increased freezing, changes in orientation and total distance, which the researchers noted could lead to increased risk of predation and challenges for the organisms to find food in the wild

  
  

• The growth rates of both organisms depended on the level of exposure to tire particles, and the growth rate of fish exposed to nano-tire particles also decreased

  
  

• Leachate affects the behavior of both organisms, but not their growth

  
  

The findings led the researchers to conclude that even at current tire-related pollution levels, aquatic ecosystems may be suffering negatively, which is expected to increase
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In the freshwater ecosystems paper led by graduate student Brittany Cunningham, embryonic zebrafish and the crustacean Daphnia magna are model organisms
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Findings:

• Both organisms experienced death and dysplasia due to exposure to tire particles and leachate
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• Tire particulate leachate is a major source of both biological toxicity
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• Exposure to nanotire particles was more toxic than exposure to leachate alone
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These findings led the researchers to conclude that while tire particle toxicity was observed in both organisms, the overall sensitivity to tire particles was different
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They believe it is important to understand these differences in order to determine the toxicity levels of these pollutants
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They point out that this awareness is critical to the creation of risk assessments, which inform policy decisions
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The researchers also mentioned several ways to limit tire particles from entering the environment
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These include installing rain gardens on the sides of roads to capture tire particles, installing particle-capturing devices on cars, developing more durable tires, and investing in green infrastructure, such as public transportation, to keep people from driving less
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