Above photo: The tool developed in this study will help monitor the toxic tire chemical 6PPD-Q in aquatic and marine environments, and help us understand the potential to bioaccumulate in marine food webs. Credit: NOAA Fisheries
Scientists at NOAA’s Northwest Fisheries Science Center helped pioneer the study of an automobile tire toxin found to kill coho salmon when it runs off highways in stormwater and into streams. Now they have found a way to measure the toxin, 6PPD-quinone, directly in marine life, including fish, shellfish and marine mammals.
The new method can help scientists better understand how the toxin affects different species, and how it reaches and moves through marine ecosystems. It can help assess effects on more species in less time. That may, in turn, help managers find ways to reduce the risk it poses to salmon and other species.
“Without being able to measure it, we won’t be able to answer questions about its impacts on species,” said Li-Jung Kuo, who led research by the Science Center’s Environmental Chemistry Program to develop the new method. “We need to have a better understanding of 6PPD-Q distribution in the environment, including aquatic species. The capability to directly measure the 6PPD-Q body burden in aquatic species is a step forward, as it is essential for exposure assessment.”
The ecotoxicologists at the Science Center led research close to two decades ago that discovered “Urban Runoff Mortality Syndrome” which has led to mass die-offs of coho salmon in the Pacific Northwest during stormwater events. The lethal effects on coho salmon can occur in a matter of hours, even at very low concentrations. Recently, 6PPD-quinone was identified as the primary causal agent of the syndrome.
Continued research also identified inexpensive means of eliminating the toxic effects by filtering contaminated runoff through soil layers such as those in rain gardens. Highway construction in Washington and other states has begun to incorporate such solutions.
6PPD-quinone is a toxic chemical that forms when 6PPD, a common tire additive used to prevent cracking and degradation, reacts with ozone in the air. As tires wear down, tiny particles containing 6PPD are released onto roads. When it rains, stormwater runoff washes these particles and the resulting 6PPD-Q into streams, rivers, and on to the ocean.
Now scientists have developed an extraction method to measure 6PPD-Q in tissue samples from shellfish, finfish, and marine mammals. The method also measures other persistent pollutants, such as PCBs, PBDE flame retardants, organochlorine pesticides, and oil-related hydrocarbons. It allows researchers to understand the chemical’s potential impact on a broader range of species. It is the first method to directly document marine animals’ exposure in the wild.
Previous monitoring for 6PPD-Q has focused primarily on water, soil, atmospheric particulate matter, road dust, and sediment. The new protocol developed by NOAA scientists allows for the extraction and quantitative analysis of the chemical in complex tissues from various aquatic organisms. The method can be used to test tissues from finfish, shellfish, and even marine mammals.
This is a significant advancement because it allows scientists to:
• Assess the potential for 6PPD-Q to accumulate in species as it moves through aquatic food webs
• Assess environmental exposure of species to 6PPD-Q
• Streamline the analysis of 6PPD-Q into existing protocols with other persistent organic pollutants, assessing more pollutants in less time and for less cost
The development of this new method is a critical step in understanding the scope of exposure of marine species. It will guide future biomonitoring efforts in aquatic environments.
“This is a well-established problem, where we understand the cause and the response,” said Irvin Schultz, a research scientist at the Science Center and senior author of the new research. “Now we have a tool to help understand how it affects marine species and their ecosystem.”
Individuals can take steps to help reduce polluted runoff entering our waterways. Here’s how you can make a difference:
Install Rain Gardens and Bioswales
These natural filtration systems use a mix of soil, compost, and plants to capture and filter stormwater runoff before it enters storm drains. Research from NOAA has shown that these simple soil mixtures are highly effective at preventing toxic effects on fish.
Support Green Stormwater Infrastructure
Advocate for and support local projects that use natural systems like permeable pavement and rain gardens to manage stormwater.
Wash Your Car on the Lawn or at a Commercial Car Wash
Instead of washing your car in the driveway where soap and grime can run into the street, wash it on a grassy area that can absorb and filter the water. Commercial car washes also treat their wastewater, preventing pollutants from entering the storm drain system.
Also see:
–CBB, August 19, 2025, “Coho Urban Runoff Mortality Syndrome: WSU Research Team Discovers How Tire Chemical 6PPD Kills Coho, Step To Finding Alternative,” https://columbiabasinbulletin.org/coho-urban-runoff-mortality-syndrome-wsu-research-team-discovers-how-tire-chemical-6ppd-kills-coho-step-to-finding-alternative/
–CBB, Nov. 16, 2023, “EPA Agrees To Begin Rulemaking On Risk To Salmon From 6PPD, A Chemical In Every Vehicle Tire; Kills Coho Within Hours,” https://columbiabasinbulletin.org/epa-agrees-to-begin-rulemaking-on-risk-to-salmon-from-6ppd-a-chemical-in-every-vehicle-tire-kills-coho-within-hours/