12.6. Results of PMT and vPvM Assessment

Overview

PMT (Persistent, Mobile and Toxic) and vPvM (very Persistent and very Mobile) substances represent an emerging class of chemicals of concern due to their potential to contaminate water resources and pose long-term risks to drinking water quality and aquatic ecosystems.

Unlike PBT substances that bioaccumulate, PMT/vPvM substances are characterized by their high mobility in the environment, particularly in water systems, making them difficult to remove once released and capable of widespread distribution.

PMT/vPvM Assessment Flow Diagram

Critical Water Resource Implications

PMT/vPvM substances pose unique challenges for water resource protection:

Assessment Criteria for PMT and vPvM Identification

Emerging Regulatory Framework

PMT/vPvM criteria are being developed based on scientific recommendations from ECHA's Information Note and research by the German Environment Agency (UBA). These criteria may be formally adopted in future REACH amendments.

Property PMT Criteria vPvM Criteria Test Methods & Indicators
Persistence (P/vP)
  • Fresh/marine water: t½ > 40 days
  • Fresh/marine sediment: t½ > 120 days
  • Soil: t½ > 120 days
  • Fresh/marine water: t½ > 60 days
  • Fresh/marine sediment: t½ > 180 days
  • Soil: t½ > 180 days
  • OECD 301 (Ready biodegradability)
  • OECD 308 (Aerobic/anaerobic transformation)
  • OECD 309 (Aerobic mineralisation)
  • OECD 314 (Simulation testing)
  • OECD 111 (Hydrolysis)
Mobility (M/vM) log Koc < 4.0 log Koc < 3.0
  • OECD 121 (Soil sorption)
  • OECD 106 (Sediment sorption)
  • OECD 312 (Leaching in soil columns)
  • Log Kow measurements
  • Groundwater monitoring data
Toxicity (T)
  • NOEC/EC10 < 0.01 mg/L (chronic aquatic)
  • CMR Category 1A or 1B
  • Endocrine disrupting properties
  • Specific target organ toxicity
  • Immunotoxicity
 Not applicable
  • OECD 210 (Fish early life stage)
  • OECD 211 (Daphnia reproduction)
  • OECD 201 (Algae growth inhibition)
  • OECD 240 (Medaka extended one generation)
  • Human health toxicity studies

Tiered Assessment Strategy for PMT/vPvM

Assessment Flow for PMT/vPvM Identification

Tier 1: Initial Screening

  • Physical-Chemical Properties: Molecular weight, water solubility, vapor pressure, log Kow
  • Mobility Indicators: Initial Koc estimates from QSAR models (KOCWIN, PCKOCWIN)
  • Persistence Screening: Ready biodegradability tests (OECD 301 series)
  • Toxicity Screening: Acute toxicity data and structural alerts for chronic effects
  • Environmental Occurrence: Monitoring data from water bodies and drinking water

Tier 2: Enhanced Assessment

  • Sorption Studies: OECD 121 (soil) and OECD 106 (sediment) sorption coefficients
  • Inherent Biodegradability: OECD 302 series if ready biodegradability is negative
  • Abiotic Degradation: Hydrolysis (OECD 111) and photolysis studies
  • Leaching Potential: OECD 312 soil column leaching studies
  • Chronic Toxicity: Long-term aquatic toxicity studies

Tier 3: Definitive Assessment

  • Simulation Testing: OECD 308 (sediment-water), OECD 309 (pelagic), OECD 314 (soil)
  • Field Studies: Groundwater monitoring, surface water fate studies
  • Advanced Toxicity: Multi-generation studies, endocrine disruption assessment
  • Transport Modeling: Fate and transport models for environmental distribution
  • Water Treatment Efficacy: Removal efficiency in drinking water treatment

Water Resource Protection Framework

Water Framework Directive Integration

PMT/vPvM substances are of particular concern under the EU Water Framework Directive and Drinking Water Directive due to their potential for widespread water contamination.

Water System Contamination Risk Protection Measures Monitoring Requirements
Surface Water
  • Direct discharge contamination
  • Runoff from treated areas
  • Atmospheric deposition
  • Long-range transport
  • Emission controls at source
  • Buffer zones and wetlands
  • Advanced treatment systems
  • Use restrictions in watersheds
  • Quarterly monitoring
  • Event-based sampling
  • Trend analysis
  • Biological monitoring
Groundwater
  • Leaching from soil
  • Industrial site contamination
  • Agricultural applications
  • Waste disposal sites
  • Soil protection measures
  • Containment systems
  • Pump-and-treat systems
  • Source zone remediation
  • Annual monitoring
  • Multi-level sampling
  • Plume delineation
  • Natural attenuation assessment
Drinking Water
  • Source water contamination
  • Treatment system breakthrough
  • Distribution system issues
  • Cross-contamination events
  • Source protection zones
  • Advanced treatment technologies
  • Real-time monitoring
  • Alternative water sources
  • Continuous monitoring
  • Point-of-use testing
  • Consumer notification
  • Health risk assessment

Emerging Regulatory Framework

Current Regulatory Status

PMT/vPvM substances are not yet formally regulated under REACH, but are under active consideration by ECHA and EU Member States. Several initiatives are developing the regulatory framework:

ECHA Initiatives

  • Information Note (2019): Initial criteria and assessment approach
  • Technical Report (2021): Refined criteria and case studies
  • Stakeholder Consultation: Industry and NGO input on implementation
  • REACH Amendment Proposal: Formal inclusion in REACH Annex XIII
  • Guidance Development: Assessment methodology and testing strategies

Member State Activities

  • Germany (UBA): Leading research on PMT/vPvM criteria and methods
  • Sweden: PFAS restrictions and PMT substance identification
  • Netherlands: Water quality protection and monitoring programs
  • Denmark: Drinking water protection and treatment technologies
  • Norway: Arctic contamination and long-range transport studies

International Cooperation

  • OECD: Test guideline development and harmonization
  • Stockholm Convention: Consideration of mobile POPs
  • UNEP: Global chemicals management and water protection
  • WHO: Drinking water guidelines and health risk assessment
  • HELCOM/OSPAR: Regional sea protection and monitoring

Scientific Assessment Methodology

Weight of Evidence Approach

PMT/vPvM assessment requires integration of multiple data sources and assessment endpoints, following principles similar to PBT assessment but with focus on mobility and water contamination potential.

Persistence Assessment

Mobility Assessment

Toxicity Assessment

Case Studies and Examples

Case Study 1: Per- and Polyfluoroalkyl Substances (PFAS)

Assessment Outcome: PMT and vPvM substances

  • Persistence: Extremely persistent due to strong C-F bonds (no environmental degradation)
  • Mobility: High water solubility and low sorption (log Koc < 2.5)
  • Toxicity: Various health effects including cancer, liver damage, immune suppression
  • Environmental Impact: Global contamination of water resources, bioaccumulation in food webs
  • Regulatory Response: Restrictions, phase-outs, drinking water standards, remediation programs

Case Study 2: 1,4-Dioxane

Assessment Outcome: PMT substance

  • Persistence: Resistant to biodegradation, moderate persistence in water
  • Mobility: High water solubility, low sorption potential
  • Toxicity: Probable human carcinogen, liver and kidney effects
  • Sources: Industrial solvent, cosmetic stabilizer, groundwater contamination
  • Management: Use restrictions, treatment technology development, monitoring programs

Case Study 3: Metformin and Pharmaceutical Metabolites

Assessment Outcome: vPvM substances

  • Persistence: Persistent metabolites in wastewater treatment and environment
  • Mobility: High water solubility, minimal sorption to sediments
  • Environmental Occurrence: Widespread detection in surface and groundwater
  • Concerns: Ecosystem effects, antibiotic resistance, endocrine disruption
  • Management Approaches: Advanced treatment, source control, green pharmacy initiatives

Case Study 4: Benzotriazole UV Stabilizers

Assessment Outcome: PMT substances

  • Persistence: Resistant to biodegradation and photolysis
  • Mobility: Moderate to high mobility in aquatic systems
  • Toxicity: Endocrine disruption, aquatic toxicity
  • Sources: Plastics, coatings, personal care products
  • Environmental Fate: Widespread occurrence in water bodies, treatment challenges

Risk Management Strategies

Precautionary Approach Required

Due to the irreversible nature of water contamination by PMT/vPvM substances, a precautionary approach emphasizing prevention over remediation is essential.

Source Control Measures

Water Treatment Technologies

Advanced Treatment Options for PMT/vPvM Removal

Technology Mechanism Effectiveness Limitations
Activated Carbon Adsorption Good for many organics Limited for highly mobile compounds, regeneration costs
Reverse Osmosis Size exclusion High removal efficiency Energy intensive, concentrate disposal
Advanced Oxidation Chemical oxidation Destroys many contaminants Formation of transformation products
Ion Exchange Ionic substitution Effective for ionic compounds Selective for charged species, resin regeneration
Membrane Bioreactors Biological degradation + filtration Good for biodegradable compounds Limited for persistent substances

Environmental Monitoring and Surveillance

Comprehensive Monitoring Strategy

PMT/vPvM substances require comprehensive monitoring across multiple environmental compartments with emphasis on water resources and potential human exposure pathways.

Monitoring Framework

Analytical Considerations

Analytical Challenges and Solutions

  • Method Development: Low detection limits, matrix interferences, polar compounds
  • Quality Assurance: Reference standards, proficiency testing, method validation
  • Data Management: Harmonized databases, trend analysis, spatial mapping
  • Emerging Contaminants: Non-target screening, suspect screening approaches
  • Transformation Products: Metabolite identification and quantification

Future Developments and Research Needs

Evolving Science and Policy

The PMT/vPvM framework is rapidly evolving with new scientific insights, analytical capabilities, and regulatory developments. Key areas of advancement include:

Scientific Research Priorities

Key Recommendations for Industry