Overview
EN ISO 23675:2025 (adoption of ISO 23675:2024) specifies a harmonized in vitro method for determining Sun Protection Factor (SPF) of sunscreen cosmetics. The method is designed for emulsions and alcoholic one‑phase formulations and explicitly excludes loose/compressed powders and sticks. It establishes reproducible procedures to measure the spectral absorbance characteristics used to calculate a static (non‑water‑resistant) in vitro SPF value.
Key topics and technical requirements
- Scope and limitations: applies only to emulsions and alcoholic one‑phase sunscreens; not applicable for powders, sticks or for evaluating water resistance.
- Measurement range: spectral absorbance measurements are carried out across the UV region used for SPF calculation (example: 290–400 nm as indicated in the procedure).
- Test substrates and materials: uses specified sample plates (double plate system), reference sunscreens and blanks (normative annexes define plate and reference product specifications).
- Apparatus and instrumentation:
- Spectrophotometer requirements and monitoring procedures (normative specifications).
- Robot or controlled spreading device for reproducible product application.
- Automatic positive‑displacement pipette and analytical balance for precise dosing.
- Solar simulator with defined UV quality and monitoring for irradiation steps.
- Procedure steps:
- Plate preparation and product application, including automated spreading.
- Initial (pre‑irradiation) absorbance measurement, calculation of pre‑irradiation in vitro SPF.
- Calculation of irradiation dose, controlled UV exposure, post‑irradiation absorbance measurement.
- Calculation and validation of final in vitro SPF per plate pair and overall test report requirements.
- Normative annexes provide detailed specifications (UV spectra, sample plate design, reference sunscreens, spectrophotometer and robot specifications).
Practical applications
- Supporting product development and formulation optimization by providing rapid SPF screening without human subjects.
- Quality control and batch consistency testing in manufacturing - reproducible in vitro readings help monitor production variability.
- Regulatory and labeling support as part of a dossier demonstrating SPF performance (not a substitute for required in vivo methods where mandated).
- Comparative testing for benchmarking formulations and evaluating photostability (static SPF changes after irradiation).
Who should use this standard
- Cosmetic manufacturers (R&D, QC and regulatory teams)
- Independent testing and analytical laboratories performing sunscreen evaluation
- Regulatory authorities and conformity assessors reviewing SPF data
- Suppliers of testing equipment (spectrophotometers, robotic spreaders, solar simulators)
Related standards
- EN ISO 23675:2025 is the CEN-endorsed version of ISO 23675:2024. Related international standards commonly used alongside SPF testing include in vivo SPF and UVA test standards (consult your national standards body for current referenced standards and regulatory requirements).
Keywords: EN ISO 23675:2025, in vitro SPF, sun protection factor, sunscreen testing, spectral absorbance, solar simulator, cosmetics standard, SPF test method.
