EPA Develops Testing Method to Improve Detection of 6PPD-Quinone in Water - Vital for Environmental Protection Initiatives

Following its November 2023 commitment to gather data on the widely used tire additive 6PPD and its chemical by-product 6PPD-quinone, the U.S. Environmental Protection Agency (EPA) has announced the release of a draft testing method (EPA Method 1634) on January 30, 2024. This method will allow government agencies, tribes, and other organizations to determine the presence of 6PPD-quinone in local stormwater and surface water.

About 6PPD

Vehicle tires contain the chemical 6PPD (chemical name: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) to prevent degradation from reactions with ozone and reactive oxygen species. When 6PPD reacts with ozone, it forms 6PPD-quinone. As tires wear down, particles are released into the environment, and when it rains, stormwater washes these particles into waterways, potentially exposing aquatic organisms to 6PPD-quinone.

Research indicates that 6PPD-quinone is toxic and can swiftly kill certain fish. A 2021 publication in the journal Science linked coho salmon deaths to 6PPD-quinone in stormwater, with lethal concentrations found within a few hours of exposure. Other fish species were also identified as vulnerable.

Apart from being used in tires for more than six decades, 6PPD is also present in various rubber products, including footwear, synthetic turf infill, and playground surfaces. EPA’s draft analytical method for detecting 6PPD-quinone is now widely available, providing tribes and local governments with a crucial tool to better understand stormwater and surface water quality. This assists in determining how to protect vulnerable aquatic creatures like salmon and trout from potential harm caused by runoff.

Draft Method 1634: Detecting 6PPD-Quinone in Water

This method uses liquid chromatography with tandem mass spectrometry (LC/MS/MS) to analyze water samples for 6PPD-quinone.

1. Samples are prepared and extracted using solid-phase extraction (SPE). An aliquot of the extracted solution is spiked with an internal standard and brought to a final volume.
2. The extract is injected into an HPLC system with a tandem mass spectrometer. 6PPD-quinone is identified by comparing mass transitions and retention time with reference spectra.
3. Quantitative determination of 6PPD-quinone concentration is performed using primary quantitation ions and corrected for recovery using isotope dilution.

This method ensures accurate analysis through reproducible calibration and testing of equipment.

Additional research

EPA is actively funding and conducting research to better understand the effects of 6PPD-quinone and to address data gaps, including the development of an analytical method. Specifically:

• EPA's Office of Research and Development is studying the fate and transport of these chemicals in air and water, their effects on ecosystems, and strategies for mitigating stormwater contamination.
• EPA's Office of Water is developing draft screening values for 6PPD-quinone and 6PPD in water to protect sensitive aquatic life. These values can be used by various parties for monitoring and water quality protection programs.
• EPA is collaborating with the National Science and Technology Council on potential research on the human health effects of 6PPD-quinone.