The hidden danger in our waterways: understanding 6PPD-Q
January 21, 2025
Shannon Roback, PhD
Science Director
Mike Dulong
Legal Program Director
If you’ve ever wondered how tiny, seemingly invisible pollutants make their way into our water systems and wreak havoc, meet 6PPD-Q. This chemical is an invisible threat with a profound impact on aquatic life, and it’s closer to home than you might think. Here’s what you need to know about 6PPD-Q, why it’s a problem, and how Riverkeeper is advocating for change.
What is 6PPDQ?
6PPD-Q, short for N-(1,3-dimethylbutyl)-N’-phenyl-p-phenylenediamine quinone, is a byproduct of a chemical called 6PPD, which is widely used as an antioxidant in tires to prevent them from breaking down too quickly. When 6PPD interacts with ozone in the air or UV light, it transforms into 6PPD-Q. While 6PPD serves a useful purpose in prolonging tire life, its byproduct has severe unintended consequences when it enters the environment.
Where is 6PPD-Q found?
As tires wear down, they release tiny particles and dust into the environment. This debris, often left on roads and surrounding areas, is carried by stormwater into nearby water bodies. The problem doesn’t stop there: improperly disposed tires are commonly found in rivers, wetlands, and other aquatic ecosystems.
Riverkeeper volunteers see this problem firsthand during our Sweep cleanups. Since 2012, our dedicated teams have removed 2,287 tires—about 22 tons—from shoreline areas in New York City and the Hudson Valley all the way north to the Adirondacks. Just this year, in 2024, volunteers collected 198 tires, including 34 from a single tire-specific cleanup in a wetland in Eddyville, New York. These efforts make an impact, but more tires are disposed into the river each year, leaching pollutants like 6PPD-Q into our waterways. What’s more, it’s common for boat docks to use tires as bumpers along piers.
Why is 6PPDQ a problem?
6PPD-Q is highly toxic to aquatic organisms. Urban runoff containing this chemical has been linked to significant mortality in species such as coho salmon, rainbow trout, and brook trout. Studies have even detected 6PPD and its byproduct in fish tissue, raising concerns about its effects throughout the food chain.
Wastewater treatment plants are not equipped to remove 6PPD or 6PPD-Q effectively. Research in New York has shown that these facilities are unable to filter out the chemical, allowing it to persist in water systems and amplify its harmful effects.
The risks to human health remain unclear, as research is still limited. However, given its acute toxicity to aquatic life and the potential for human exposure through water and food, this is a problem that demands urgent attention.
What does Riverkeeper advocate for?
At Riverkeeper, we’re committed to safeguarding the health of our waterways and the life they support. Riverkeeper provided comments to the EPA calling for a prohibition on the manufacturing, processing, use, and distribution of 6PPD. This chemical’s continued presence in tires is a major contributor to water contamination, and we urge manufacturers to discontinue its use. Riverkeeper also wrote to the New York State DEC calling for stringent 6PPD pollution limits in our waters.
But banning 6PPD is only part of the solution. We also advocate for caution and thorough research into alternatives. Early studies have already found 6PPD replacements in human plasma and urine, highlighting the need to ensure these substitutes are safe for both humans and the environment. Riverkeeper is now sampling some areas of the Hudson River and its tributaries to measure the presence of 6PPD-Q.
How you can help
Protecting our waterways is a shared responsibility. By joining efforts like Riverkeeper’s annual Sweep cleanups, you can play a part in reducing tire-related pollution. Together, we can remove harmful debris and raise awareness about the hidden dangers lurking in our environment.
Every tire pulled from a riverbank or wetland is one less source of toxic pollution. Let’s work together to ensure that our waterways remain clean, safe, and vibrant for generations to come.
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