12.5 Results of PBT and vPvB Assessment

This section provides the results of the assessment of Persistent, Bioaccumulative and Toxic (PBT) and very Persistent and very Bioaccumulative (vPvB) properties of substances. This assessment is crucial for identifying substances that may pose long-term risks to the environment due to their persistence, tendency to accumulate in organisms, and toxicity.

PBT and vPvB Overview

PBT and vPvB substances are of particular concern because they:

Persist in the environment: Remain intact for long periods
Bioaccumulate: Accumulate in living organisms and can biomagnify through the food chain
Are toxic (PBT only): Cause adverse effects to human health or the environment
Can be transported long distances: May be found far from their sources
Are difficult to remove once released: Cannot be easily remediated

Substances identified as PBT or vPvB may be subject to authorization or restriction under REACH and may require specific risk management measures to minimize releases to the environment.

Regulatory Framework

The PBT and vPvB assessment is required under several regulatory frameworks:

REACH Regulation (EC) No 1907/2006: Annex XIII sets criteria for PBT and vPvB identification
Biocidal Products Regulation (EU) No 528/2012: Requires PBT assessment for active substances
Plant Protection Products Regulation (EC) No 1107/2009: Includes PBT criteria for approval of active substances
Stockholm Convention on Persistent Organic Pollutants (POPs): International agreement on persistent organic pollutants
Water Framework Directive (2000/60/EC): Identifies priority hazardous substances

PBT and vPvB Criteria

Under REACH Annex XIII, the criteria for PBT and vPvB identification are:

Property	PBT Criteria	vPvB Criteria
Persistence (P/vP)	Half-life > 60 days in marine water, or Half-life > 40 days in fresh water, or Half-life > 180 days in marine sediment, or Half-life > 120 days in freshwater sediment, or Half-life > 120 days in soil	Half-life > 60 days in marine or fresh water, or Half-life > 180 days in marine or freshwater sediment, or Half-life > 180 days in soil
Bioaccumulation (B/vB)	BCF > 2000	BCF > 5000
Toxicity (T)	NOEC or EC₁₀ < 0.01 mg/L for marine or freshwater organisms, or Substance is carcinogenic (Cat. 1A or 1B), mutagenic (Cat. 1A or 1B), or toxic for reproduction (Cat. 1A, 1B, or 2), or Evidence of chronic toxicity (STOT RE Cat. 1 or 2), or Endocrine disrupting properties with adverse effects	Not applicable

Assessment Approach

The PBT/vPvB assessment follows a weight-of-evidence approach using expert judgment, considering all available relevant information:

Screening assessment: Initial evaluation based on readily available data
Definitive assessment: Comprehensive evaluation using high-quality data
Integrated assessment: Consideration of all available information in a weight-of-evidence approach

Assessment Sequence:

Gather all available data on P, B, and T properties
Evaluate persistence (P/vP) against criteria
If potentially P/vP, evaluate bioaccumulation (B/vB)
If potentially P/vP and B/vB, evaluate toxicity (T) for PBT assessment
Draw conclusions on PBT and vPvB status

Example: PBT/vPvB Assessment Results

Property	Data	Criteria	Conclusion
Persistence	Ready biodegradability: 65% degradation in 28 days (OECD 301B) Half-life in water: 15-25 days Half-life in soil: 30-45 days Half-life in sediment: 45-60 days	P: Half-life > 40 days (fresh water) vP: Half-life > 60 days (water)	Not P/vP
Bioaccumulation	Log K_ow: 3.2 BCF (fish): 250 L/kg Metabolism: Moderate	B: BCF > 2000 vB: BCF > 5000	Not B/vB
Toxicity	Fish NOEC (28d): 1.2 mg/L Daphnia NOEC (21d): 0.8 mg/L Algae ErC₁₀: 2.5 mg/L Not CMR, STOT RE, or ED	T: NOEC < 0.01 mg/L or CMR, STOT RE, or ED properties	Not T
Overall Conclusion	The substance does not meet the criteria for PBT or vPvB.

Assessment Details

Test Methods Used

Persistence:
- OECD 301B: Ready Biodegradability - CO₂ Evolution Test
- OECD 308: Aerobic and Anaerobic Transformation in Aquatic Sediment Systems
- OECD 307: Aerobic and Anaerobic Transformation in Soil
Bioaccumulation:
- OECD 305: Bioaccumulation in Fish: Aqueous and Dietary Exposure
- OECD 107: Partition Coefficient (n-octanol/water): Shake Flask Method
Toxicity:
- OECD 210: Fish, Early-life Stage Toxicity Test
- OECD 211: Daphnia magna Reproduction Test
- OECD 201: Freshwater Alga and Cyanobacteria, Growth Inhibition Test

Data Reliability

The reliability of data used in the PBT/vPvB assessment is evaluated using the Klimisch scoring system:

Klimisch 1: Reliable without restrictions (GLP studies, standardized guidelines)
Klimisch 2: Reliable with restrictions (non-GLP studies, non-standard methods but well-documented)
Klimisch 3: Not reliable (significant methodological deficiencies)
Klimisch 4: Not assignable (insufficient documentation)

For this assessment, only data with Klimisch scores of 1 or 2 were used for the definitive evaluation. Where multiple studies were available, a weight-of-evidence approach was applied, giving preference to higher quality studies.

Uncertainties and Limitations

Experimental variability: Test results may vary between laboratories and test conditions
Extrapolation: Laboratory tests may not fully represent environmental conditions
Metabolites: Transformation products may have different properties than the parent compound
Complex substances: For UVCBs and multi-constituent substances, assessment is more challenging
Field data limitations: Environmental monitoring data may be limited or absent

The assessment is based on currently available data and may be subject to revision if new information becomes available.

Regulatory Context

REACH requirements: PBT/vPvB assessment is mandatory for substances manufactured or imported at ≥ 10 tonnes/year
Applicable thresholds: The assessment applies to the substance itself, its constituents, and relevant transformation products
Compliance status: The substance does not meet PBT or vPvB criteria and is not subject to authorization based on these properties
Risk management implications: Standard risk management measures are sufficient; no specific PBT/vPvB-related measures required

Implications of PBT/vPvB Status

If a substance were identified as PBT or vPvB, the following would apply:

Chemical Safety Assessment would require emission characterization and minimization
The substance could become a candidate for REACH authorization
Specific risk management measures would be required to minimize releases
Substitution with safer alternatives would be encouraged
Environmental monitoring might be required

Recent Developments in PBT/vPvB Assessment

PMT/vPvM criteria: Persistent, Mobile, and Toxic / very Persistent and very Mobile substances are being considered as an additional category of concern
Endocrine disruption: Enhanced consideration of endocrine disrupting properties in the toxicity assessment
Mixture assessment: Improved approaches for complex substances and mixtures
New analytical methods: Advanced techniques for detecting low concentrations in environmental samples
Computational approaches: Development of in silico methods for predicting PBT properties

Quality Assurance Checklist

Verify that all relevant data for P, B, and T assessment has been considered
Ensure that the assessment follows the criteria in REACH Annex XIII
Check that the data quality and reliability have been evaluated
Confirm that a weight-of-evidence approach has been applied
Verify that the conclusion is clearly stated and justified
Ensure that any uncertainties or data gaps are acknowledged