Overview
ISO 16217:2020 - "Cosmetics - Sun protection test methods - Water immersion procedure for determining water resistance" defines an in vivo water immersion procedure to evaluate the water resistance of sunscreen products. Designed to be used together with ISO 24444 (in‑vivo SPF determination), the standard specifies how to challenge applied sunscreens in a simulated swim environment and how to calculate post‑immersion and water‑resistance Sun Protection Factor (SPF) metrics.
Key topics and technical requirements
- Scope and applicability
- Applies to products intended for contact with human skin that absorb, reflect or scatter UV and are formulated to resist removal by water.
- Test population
- Minimum of 10 test subjects; specific informed consent (including water immersion duration and potential chill) is required in line with the Declaration of Helsinki.
- Test area and application
- Test sites are located on the back (between scapula line and waist) and must be fully immersed during the procedure. Product application follows ISO 24444 protocols.
- Water immersion procedure
- Room temperature: 20–26 °C. Water temperature: 30 ± 2 °C.
- Use a simulated swim test device (spa/whirlpool design) as described in Annex A.
- Immersion cycle: 20 minutes immersion (water circulated) followed by 5–20 minutes drying (no towelling). Repeat cycles for target water‑resistance durations (e.g., two cycles for 40 min, four cycles for 80 min).
- Final drying: allow test areas to be free of visible droplets and dry for at least 15 minutes before UV exposure.
- Positioning and safety
- Subjects are seated to avoid contact of test sites with spa sides, other subjects, or direct water jet impingement.
- Validation and calculation
- Labs must validate the immersion procedure using the P2 high‑SPF reference sunscreen on a defined frequency (every 200 subjects or every 2 months) to ensure consistent post‑water immersion SPF results.
- Definitions and calculations for individual water resistance SPF (SPFiwr), post‑water immersion SPF, and water resistance SPF (SPFwr) are provided; calculation integrates MED values as per referenced methods.
Applications and users
ISO 16217:2020 is used by:
- Cosmetic testing laboratories and clinical trial facilities for claim substantiation of water resistance.
- Sunscreen manufacturers and formulators during product development, QA and regulatory submissions.
- Regulatory authorities and standards bodies evaluating sun protection performance and labeling claims.
- Third‑party certification and consumer safety organizations verifying in‑use durability of sun care products.
Related standards
Keywords: ISO 16217:2020, water resistance, sunscreen testing, water immersion procedure, SPF, simulated swim test device, in vivo sun protection, post‑water immersion SPF.