By Erwan Saouter | SSbD-Expert.euIndependent Expert in LCA Toxicity, Chemical Risk Assessment and Safe & Sustainable by Design

The Major Breakthrough: USEtox Near-Field

A Fundamental Methodological Innovation

Historically, USEtox was limited to far-field exposure: environmental emissions (air, water, soil) leading to indirect exposure via inhalation of ambient air, ingestion of drinking water, or contaminated food. This approach ignored a reality demonstrated by numerous studies: direct exposure to chemical substances in consumer products often vastly exceeds environmental exposure.

The work of Fantke et al. (2021) demonstrated that exposure related to product use can exceed exposure from environmental emissions throughout the life cycle by several orders of magnitude.

The Integrated Framework

The new USEtox framework proposes a single matrix combining:

1. Far-field compartments (outdoor air, water, soil)
2. Near-field compartments (indoor air, surfaces, skin)
3. Human receptor compartments (inhalation, ingestion, dermal absorption)

Key advantages:

✅ Comparability: Product Intake Fractions (PiF) are expressed in the same unit as classical Intake Fractions (kg intake / kg inventory)

✅ Consistency: Same matrix approach, same dose-response factors, same severity factors (DALY/incidence)

✅ Completeness: Captures exposure across the entire life cycle, including the use phase

Available Product Modules

USEtox near-field includes five transfer modules for different product types:

• Article interior: building materials, furniture, toys
• Skin surface layer: cosmetics, personal care products
• Object surface: cleaning products
• Food contact materials: food packaging
• Direct emission: direct emissions into the indoor environment

Why USEtox Near-Field ≠ ConsExpo

Key Methodological Differences

1. Exposure Scenarios

USEtox Near-Field:

• Generic and averaged scenarios
• Default parameters (room volumes, ventilation rates, usage frequencies)
• Objective: enable product comparison on a standardized basis

ConsExpo:

• Product-specific and adjustable scenarios
• Ability to model worst-case or realistic conditions
• Probabilistic distributions to account for inter-individual variability

2. Temporality

USEtox:

• Cumulative lifetime exposure (70 years)
• Expressed in DALY (disability-adjusted life years)
• Integrates severity and duration of effects

ConsExpo:

• Acute (event-based) or chronic (long-term average) exposure
• Direct comparison with toxicological thresholds (DNEL acute, DNEL chronic)
• Allows evaluation of exposure peaks

3. Toxicological Endpoints

USEtox:

• Probabilistic dose-response factors derived via WHO framework
• Aggregation into 3 categories: cancer, reproductive/developmental, other non-cancer
• DRF expressed as incidence risk/kg intake

ConsExpo / REACH:

• Substance-specific DNEL (Derived No Effect Level)
• Established by industry and validated by authorities (ECHA)
• Include explicit uncertainty factors (AF)

When to Use What?

Use USEtox Near-Field For:

✅ Alternatives Assessment (AAC): Compare multiple candidate formulations

✅ Eco-design / SSbD: Identify exposure hotspots in the life cycle

✅ Screening: Prioritize substances/products requiring in-depth evaluation

✅ Communication: Quantify substitution benefits in terms of health impact

Example: Compare 3 food packaging formulations to identify the one with the lowest overall health impact potential (production + use + end-of-life).

Use ConsExpo For:

✅ REACH Compliance: Document safety of use (CSR / ES)

✅ Notification: Prepare CLP, Biocides, Cosmetics dossiers

✅ Risk management: Define safe use conditions (RMM)

✅ Due diligence: Assess safety margins for specific products

Example: Demonstrate that a new nail polish complies with DNELs for all CMR substances it contains.

Conclusion

The integration of the near-field module into USEtox is a methodological revolution for LCA toxicity. It finally captures consumer exposure in a framework consistent with environmental emissions, offering a complete life cycle view.

But this advancement does not exempt from regulatory risk assessments. The two approaches answer different questions and complement each other:

• USEtox → "Which alternative to choose?" (relative comparison)
• ConsExpo → "Is this alternative safe?" (absolute compliance)

In a mature SSbD strategy, both are indispensable. The pragmatic use of USEtox near-field requires data collection that also enables ConsExpo assessment. Why not benefit from both perspectives!

In summary: USEtox near-field and ConsExpo are not competitors, but complementary partners in the SSbD methodological toolkit. Using them jointly maximizes both scientific rigor and regulatory relevance of your assessments.

References

Fantke, P., et al. (2021). "Exposure and toxicity characterization of chemical emissions and chemicals in products: global recommendations and implementation in USEtox." The International Journal of Life Cycle Assessment, 26:899–915.DOI: 10.1007/s11367-021-01889-y

Additional resources:

• Official USEtox website: usetox.org
• ConsExpo Web: consexpoweb.nl
• ECHA - Guidance on Consumer Exposure Assessment
• WHO (2014, 2017) - Guidance on uncertainty in hazard characterization

About the Author

Erwan Saouter is an independent expert in Life Cycle Assessment (LCA), environmental toxicity, and Safe & Sustainable by Design (SSbD).

With over 30 years of experience, including a career at the Joint Research Centre (JRC) of the European Commission, he has developed expertise in both LCA and RA.

Today, he supports industry, authorities, and researchers in the operational implementation of SSbD principles, from chemical risk assessment to eco-design of sustainable products.

Contact: ssbd-expert.eu

Article published on 2/12/2025 | Last updated: 

Keywords: Safe and Sustainable by Design, SSbD, USEtox, ConsExpo, REACH, LCA toxicity, chemical risk assessment, alternatives assessment, consumer exposure, near-field exposure