Methods

SPF and UVA methods

Testing performed in accordance with internationally recognised standards. We combine established ISO methods with the new in vitro and hybrid methodologies.

Table 1. Sunscreen testing methods performed at ISD Research.
Standard	Method	Type	Measures	Test system
ISO 24444	In vivo determination of the sun protection factor (SPF)	In vivo	SPF	Volunteers (back)
ISO 24442	In vivo determination of sunscreen UVA protection	In vivo	UVA-PF	Volunteers (back)
ISO 24443	Determination of sunscreen UVA photoprotection in vitro	In vitro	UVA-PF, UVA-PF/SPF ratio, critical wavelength	No volunteers (PMMA plates)
ISO 23675 Pioneers	In vitro determination of SPF (Double Plate)	In vitro	SPF	No volunteers (PMMA plates)
ISO 23698 Pioneers	Sunscreen efficacy by diffuse reflectance spectroscopy (HDRS)	Hybrid	SPF, UVA-PF and critical wavelength	Volunteers, no erythema
ISO 16217	Water immersion procedure for determining water resistance	In vivo	SPF after immersion	Volunteers

ISO 24444

In vivo

In vivo determination of the sun protection factor (SPF)

The reference method for SPF. The minimal erythemal dose on protected and unprotected skin of volunteers is compared under a solar simulator.

Measures: SPF
Test system: Volunteers (back)
Used for: SPF claims and reference studies.

Test sites on the back with product application — Test sites on the back. Illustrative image.

ISO 24442

In vivo

In vivo determination of sunscreen UVA protection

Determination of the UVA protection factor in volunteers through UVA-induced persistent pigment darkening (PPD).

Measures: UVA-PF
Test system: Volunteers (back)
Used for: UVA claims where an in vivo method is required.

ISO 24443

In vitro

Determination of sunscreen UVA photoprotection in vitro

Spectrophotometric measurement of product applied on PMMA plates, before and after irradiation, to calculate UVA protection and critical wavelength.

Measures: UVA-PF, UVA-PF/SPF ratio, critical wavelength
Test system: No volunteers (PMMA plates)
Used for: UVA claims (e.g. EU UVA logo) and screening.

ISO 23675

In vitroPioneers

In vitro determination of SPF (Double Plate)

The first ISO method to determine SPF entirely in vitro, using robotised application on two types of PMMA plate and spectrophotometric measurement.

Measures: SPF
Test system: No volunteers (PMMA plates)
Used for: Prototype screening and SPF claims without exposing volunteers.

ISO 23698

HybridPioneers

Sunscreen efficacy by diffuse reflectance spectroscopy (HDRS)

A hybrid method combining diffuse reflectance measured on volunteers’ skin with an in vitro measurement. It induces no erythema or pigmentation and is done in a single session.

Measures: SPF, UVA-PF and critical wavelength
Test system: Volunteers, no erythema
Used for: Combined SPF and UVA determination with a lower burden on volunteers.

ISO 16217

In vivo

Water immersion procedure for determining water resistance

Standardised water immersion procedure, combined with SPF determination to support water-resistance claims.

Measures: SPF after immersion
Test system: Volunteers
Used for: “Water resistant” and “very water resistant” claims.

Immersion bath for water-resistance studies.

Which method does your product need?

It depends on the claim, the market and the development stage. We advise you before the study is designed.

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