Overview
SIST EN ISO 24444:2020 (ISO 24444:2019) is the international in vivo method for determining the sun protection factor (SPF) of sunscreen products. The standard specifies a controlled human-subject test procedure and acceptance criteria to evaluate protection of human skin against erythema induced by solar ultraviolet (UV) radiation. It applies to cosmetics that contain components capable of absorbing, reflecting or scattering UV rays and that are intended for contact with human skin.
Key topics and technical requirements
The standard provides a comprehensive test protocol and supporting requirements, including:
- General principle and scope - in vivo SPF measurement for sunscreens and sun-protective cosmetics.
- Test subjects - selection criteria, skin-colour classification, age and participation frequency, ethical consent and the required number of subjects. (See Annex A for selection criteria.)
- Apparatus and UV source - specifications for UV solar simulators, beam uniformity, total irradiance and quality checks. (Annex B defines UV solar simulator output.)
- Maintenance and monitoring - spectroradiometry and radiometry requirements to ensure consistent irradiance during testing.
- Reference materials - reference sunscreen formulations and standards for calibration and validation (Annex C).
- Procedure - controlled test conditions, subject positioning, product application, minimal erythemal dose (MED) assessment and erythema grading. Visual guidance and colorimetric skin-typing are provided (Annexes E and F).
- Calculations and statistics - how to compute individual and product SPF values, statistical criteria for validity and test reporting (Annex D).
- Reporting - required test report elements and a sample report form (Annex G).
Practical applications and who uses this standard
SIST EN ISO 24444:2020 is used by:
- Cosmetic manufacturers for product development, SPF claim substantiation and batch release testing.
- Independent testing laboratories that perform standardized in vivo SPF evaluations.
- Regulatory authorities and conformity assessors reviewing SPF claims and safety data.
- R&D and quality assurance teams validating formulation changes, comparative performance studies and stability effects on SPF.
Benefits include reproducible SPF values, harmonized testing across markets (endorsed as EN ISO), and defensible data for labeling, marketing and regulatory compliance.
Related standards (if applicable)
- ISO 24443 (related test methods for UVA protection) and other ISO/CEN cosmetics testing standards often used alongside ISO 24444 for full-spectrum sun-protection evaluation. Check national regulations and regional CEN requirements for additional conformity obligations.
Keywords: ISO 24444, SIST EN ISO 24444:2020, SPF testing, in vivo sun protection factor, sunscreen testing, UV solar simulator, MED, cosmetics standard.