6PPD-Quinone (6PPD-Q)[edit]

Pollutant Information[edit]

Chemical Formula:	C18H23N2O2
Pollutant Family:	Tire rubber-derived quinones
CAS Number:	2754428-18-5
Molecular Weight:	299.39 g/mol
Solubility:	Water-soluble
Persistence:	Persistent in environment
Regulatory Status:	EPA emerging contaminant priority

Overview[edit]

6PPD quinone (6PPD-Q) is a toxic transformation product formed when the tire preservative chemical 6PPD reacts with ozone in the air. First identified in 2020, 6PPD-Q has been linked to the mysterious die-offs of coho salmon in urban streams across the Pacific Northwest that had puzzled scientists for 25 years. This emerging contaminant is now recognized as one of the most toxic chemicals to aquatic life and represents a significant threat to sensitive fish species and aquatic ecosystems.

Characteristics[edit]

Physical Properties[edit]

State at room temperature: Solid
Color/Appearance: Dark-colored crystalline solid
Odor: Characteristic quinone odor
Melting point: Research ongoing
Boiling point: Decomposes before boiling
Density: Higher than water

Chemical Properties[edit]

pH effects: Stability varies with pH; more persistent at neutral to alkaline pH
Oxidation states: Quinone form is primary environmental concern
Reactivity: Reactive quinone structure; forms DNA adducts
Stability: Persistent in aquatic environments
Bioavailability: Highly bioavailable to aquatic organisms

Environmental Behavior[edit]

Mobility in soil: Moderate to high mobility
Water solubility: Sufficiently water-soluble to enter waterways via runoff
Volatility: Low volatility
Adsorption: Can bind to organic matter and sediments
Half-life: Research ongoing, appears persistent in environment

Sources & Contamination Pathways[edit]

Industrial Sources[edit]

Tire manufacturing facilities
Rubber processing plants
Automotive manufacturing

Transportation Sources[edit]

Vehicle tire wear on roadways (primary source)
Tire wear particles from highways and urban roads
Parking lots and heavily trafficked areas
Bridge crossings over waterways

Urban/Residential Sources[edit]

Urban stormwater runoff
Road dust containing tire wear particles
Atmospheric deposition from roadway areas

Natural Sources[edit]

None - 6PPD-Q is entirely anthropogenic

Environmental & Health Impacts[edit]

Effects on Land/Soil[edit]

Soil chemistry: May alter soil pH and nutrient cycling
Soil biology: Potential impacts on soil microorganisms and invertebrates
Plant uptake: Limited research on plant uptake mechanisms
Groundwater contamination: Can leach into groundwater systems
Ecosystem disruption: Disrupts food webs starting with sensitive fish species

Effects on Water Systems[edit]

Aquatic toxicity: Extremely toxic to coho salmon (LC50: 95 ng/L), brook trout, rainbow trout
Bioaccumulation: Accumulates in fish tissue, especially liver
Water quality: Degrades water quality in urban streams and rivers
Widespread distribution: Found from urban rivers to deep-sea environments

Human Health Effects[edit]

Acute Exposure[edit]

Limited human data available
Potential respiratory irritation from tire dust

Chronic Exposure[edit]

DNA adduct formation observed in laboratory studies
Potential liver toxicity and metabolic disruption
Neurotoxicity and developmental concerns under investigation
Inflammatory pathways activation

Vulnerable Populations[edit]

Children: Higher exposure risk due to smaller body size
Pregnant women: Potential placental transfer to developing fetus
Communities near highways: Higher exposure from tire wear particles
Workers: Tire manufacturing and automotive workers

Detection & Testing[edit]

Sampling Methods[edit]

Water sampling: Grab samples during storm events for highest concentrations
Stormwater sampling: Event-composite sampling recommended
Sediment sampling: Core samples from urban waterways
Biological sampling: Fish tissue analysis for bioaccumulation studies

Analytical Methods[edit]

LC-MS/MS (Liquid Chromatography-Tandem Mass Spectrometry) - Detection limit ~1 ng/L
EPA Draft Method 1634 for surface water and stormwater
High-resolution mass spectrometry for metabolite identification

Regulatory Limits[edit]

EPA screening values: Developed for protecting sensitive salmon species
Acute toxicity threshold: 95 ng/L for coho salmon (revised 2022)
No established drinking water standards yet
State guidelines: Washington State developing water quality criteria

Bioremediation Organisms[edit]

Fungi[edit]

Phanerochaete chrysosporium - Multifunctional enzyme degradation, 99% removal in 7 days
White-rot fungi - Lignin peroxidase, manganese peroxidase, laccase enzymes

Bacteria[edit]

Research ongoing - bacterial degradation pathways under investigation
Biological sludge systems - 85% reduction observed over 14 days

Plants (Phytoremediation)[edit]

Research in early stages - plant uptake and metabolism being studied
Potential for constructed wetland applications

Bioremediation Strategies[edit]

Bioretention Systems[edit]

High-performance bioretention soil mix: Enhanced soil media for stormwater treatment
Green infrastructure: Bioswales and rain gardens with amended soil
Engineered wetlands: Constructed wetlands for tire particle capture
Mycofiltration: Fungal-based filter systems

Advanced Biological Treatment[edit]

Fungal bioreactors: P. chrysosporium enzyme systems
Activated sludge enhancement: Biological treatment plant modifications
Biofilm systems: Fixed-film biological treatment

Alternative Treatment Methods[edit]

Physical Treatment[edit]

Mobile stormwater filters: Bridge-mounted filtration systems
Tire particle capture: Source control at roadways
Sedimentation: Settling ponds for tire wear particle removal

Chemical Treatment[edit]

Advanced oxidation: UV-activated periodate, ozone treatment
Peroxymonosulfate (PMS): Unactivated oxidation generates singlet oxygen
Activated carbon: Adsorption treatment
Metal-organic frameworks: Novel 3D framework materials for adsorption

Source Reduction[edit]

Tire chemistry alternatives: Research into safer 6PPD replacements
Tire design improvements: Reduced wear particle generation
Road surface modifications: Less abrasive pavement materials

Case Studies[edit]

Nisqually Tribe Mobile Stormwater Filter - Ohop Valley, Washington[edit]

Location: Bridge crossing in Ohop Valley, Washington
Contamination source: Highway runoff containing tire wear particles
Treatment method: Mobile stormwater filtration system
Organisms used: Physical filtration (pre-biological treatment)
Duration: Installed 2022, ongoing monitoring
Results: Reduces tire particle loads entering salmon habitat
Partners: Nisqually Tribe, Long Live the Kings nonprofit
Source: EPA 6PPD-quinone fact sheet, 2024

P. chrysosporium Laboratory Treatment Study[edit]

Location: Laboratory-scale study
Contamination source: Synthetic 6PPD-Q solutions
Treatment method: White-rot fungal degradation
Organisms used: Phanerochaete chrysosporium
Duration: 7 days
Results: 99.06% removal efficiency, detoxified metabolites
Innovation: Multifunctional enzyme system breaks down quinone toxicity
Source: ScienceDirect research paper, 2025

Prevention Strategies[edit]

Source Reduction[edit]

Development of safer tire antioxidant alternatives to 6PPD
Improved tire manufacturing to reduce wear particle generation
Traffic reduction strategies in sensitive watersheds

Infrastructure Best Management Practices[edit]

Green infrastructure implementation in urban areas
Bioretention systems along transportation corridors
Road design modifications to capture runoff
Bridge runoff treatment systems

Groups & Projects Working on This Pollutant[edit]

University of Washington Tacoma - Environmental Chemistry Lab - Tire wear particle research - Multiple publications on 6PPD-Q discovery
EPA Office of Research and Development - Chemical Safety Research - 6PPD-Q Action Plan development - National coordination
Washington State Department of Ecology - Toxic Chemicals Program - Stormwater treatment guidance - State regulatory development
Nisqually Tribe Environmental Department - Watershed protection - Mobile filter installation - Tribal leadership on solutions
Long Live the Kings - Salmon conservation - Stormwater treatment projects - Community partnerships
Interstate Technology Regulatory Council (ITRC) - Multi-state coordination - Technical guidance development - Regulatory collaboration

Resources[edit]

Scientific Literature[edit]

Tian et al. (2021). "A Ubiquitous Tire Rubber–Derived Chemical Induces Acute Mortality in Coho Salmon." Science 371:185-89
Tian et al. (2022). "6PPD-Quinone: Revised Toxicity Assessment and Quantification with a Commercial Standard." Environmental Science & Technology Letters
Yu et al. (2025). "6PPD-quinone degradation by unactivated peroxymonosulfate via direct oxidation." Chemical Engineering Journal

Government Resources[edit]

EPA 6PPD-quinone Research and Action Plan (2024)
Washington State Department of Ecology 6PPD Fact Sheet
USGS 6PPD-quinone Environmental Health Program

Testing & Analysis[edit]

ALS Environmental - 6PPD-Q analytical services - LC-MS/MS analysis
TestAmerica Laboratories - Emerging contaminant testing - EPA Method 1634
University research labs - Contact state environmental agencies for testing resources

Related Pollutants[edit]

6PPD (parent compound) - Source chemical that transforms to 6PPD-Q
Other PPD-quinones - Related tire rubber-derived transformation products
1,3-Diphenylguanidine (DPG) - Co-occurring tire additive
Benzothiazoles - Other tire-derived chemicals in stormwater
PAHs (Polycyclic Aromatic Hydrocarbons) - Co-contaminants in tire wear particles

Last updated: June 24, 2025
Page maintainer: Bioremmy