SPF : Which Way to Turn?

Your options for Sun Protection Factor [SPF] testing will very soon be expanded to include 2 new ISO methods which are almost certain to be finalised by the end of this year. The new options are?? ISO 23675 (Ed. 1) Cosmetics — Sun protection test Methods — In Vitro determination of Sun Protection Factor and ISO 23698 Ed. 1. Cosmetics Sun protection test methods- Measurement of the Sunscreen Efficacy by Diffuse Reflectance Spectroscopy (HDRS)

Both are currently passing through the final drafting process and have very high certainty of being approved and published as ISO Standards. In some parts of the world, these will have rapid adoption, whilst in others they might remain with lower regulatory recognition applicable only use in the product development phase but not for certification. For example, the E.U. has already recognised both for non-certifying use well prior to finalisation, whereas USA only accepts the FDA SPF method and is not a party to ISO.

The 2 new methods are substantially different. ISO 23675 has its origins in the already used ISO 24443 method for UVA Protection factor, utilising PMMA plastic slides in place of human skin and currently regulated and interpreted in Australia as “Broad Spectrum”, whilst ISO 23698 is based on direct instrumental measurement on the skin by a specialised spectrophotometer.?

As with many new methodologies, it will be some time before feedback from the test lab coalface unravels the intricacies of the broad range of product formulations that have to be dealt with.

The comparison chart below sets out some of the commonality and differences for these methods.?

Standards Australia is aligned with the principle of adoption of ISO test methods, but that does not mean that they will be automatically adopted into AS/NZS 2604. At this point, neither of the methods has provision for our requirement for SPF to be reported post water immersion and this link is not made in the scope of these new ISO documents.

The biggest challenge for Sponsors of sunscreen products is most likely to revolve around inconsistencies which will (and already) appear between testing of the same product according to differing methods. This is already evident in the case of sunscreens which contain inorganic actives such as Zinc oxide. In the extreme, this scenario could result in legal challenges between companies and from regulators or consumer groups.???

Until the new methods are fully scoped, it is most likely that the best course of action is to consider their utility as restricted to work up and optimisation of new product formulations i.e. for comparative guidance only.