In December 2024, the International Organization for Standardization (ISO) officially approved the ISO 23675 in vitro SPF test method, marking a major milestone in sunscreen testing. This new fully in vitro method offers a more ethical, faster, and cost-efficient alternative to the traditional in vivo SPF testing. It is based on UVR transmittance spectroscopy and provides reliable predictions of SPF values by measuring UVR transmission through specific UVR-transparent substrates. This method is not only non-animal but also significantly more reproducible and reliable compared to in vivo tests, according to experts in the field.
ISO Approves In Vitro Double Plate Method: 2025 to Bring Faster, More Ethical, and Accurate SPF Testing.
The ISO 23675 in vitro SPF test is designed for sunscreens in emulsion or alcoholic one-phase formulations, but it is not applicable to powder or stick forms. Additionally, it is intended solely for determining the static SPF and is not validated for assessing the water resistance properties of sunscreen products. As a result, it offers a streamlined and efficient alternative to previous testing methods, which required invasive human tests, and often resulted in lengthy processes and high costs.
Historically, SPF values have been determined using in vivo methods (ISO 24444), which relied on human testing for erythema and Persistent Pigment Darkening (PPD) assessments. However, these methods raise ethical concerns, are time-consuming, and involve considerable costs. The need for an in vitro SPF test has long been recognized due to its potential to eliminate human testing, speed up the process, reduce costs, and improve the repeatability and reproducibility of results.
ISO Approves In Vitro Double Plate Method: 2025 to Bring Faster, More Ethical, and Accurate SPF Testing.
The approval of the ISO 23675 method represents a significant advancement for the industry. According to Marc Pissavini, Ph.D., director of the sun research lab at Coty and chairman of ISO WG7/TC 217, this new method offers numerous advantages, including ethical considerations, better reproducibility, and a reduction in analysis time and costs. The method reduces testing from several weeks to just a few days, while costs decrease from thousands of euros or dollars to just a few hundred.
The adoption of the ISO 23675 method is voluntary, and while it is recognized internationally, its implementation will depend on individual countries. Pissavini expressed optimism that it would be widely accepted, though he noted that it may take longer to gain traction in regions like the USA and Japan. On the other hand, Sébastien Miksa, general manager of Weneos, indicated that the European Union is poised to adopt this method quickly, as the EU’s recommendations already emphasize a preference for in vitro testing methods that provide equivalent UVB protection.
“The future of sunscreen testing looks incredibly promising, and I’m excited to see these advancements come to life,” Miksa shared, echoing the optimism surrounding the method’s potential.
Pissavini also noted that 2025 will be a pivotal year for photoprotection, adding, “Finally, in 2025, we will have a robust alternative method to the historical SPF in vivo method. This is a turning point in the world of photoprotection.”
With the ISO 23675 method now fully approved, the sunscreen industry can look forward to a new era of ethical, efficient, and accurate SPF testing.
