Just a few years ago, determining SPF values without human involvement seemed like a distant possibility—more of a concept than a real standard. Today, it is becoming a reality, one that is beginning to redefine how we think about testing sunscreen products.
This change is not solely the result of technological progress. It is a response to specific tensions between the expectations of regulators, manufacturers in the cosmetics industry, and consumers themselves.
Why do traditional in vivo methods and tests on volunteers raise concerns?
In vivo SPF testing, although considered the gold standard (in accordance with ISO 24444), has long been the subject of controversy. First, there were ethical concerns. Testing on volunteers, which involved exposing their skin to UV radiation, became increasingly difficult to justify in the context of growing public sensitivity.
Second, the reproducibility of results. Even when following a rigorous protocol, the biological variability among participants influenced the final outcome. For the manufacturer, this posed a risk; for the regulator, it presented an interpretive challenge regarding how reliably to determine the declared sun protection factor.
Third, time and cost. The in vivo method is logistically complex, requiring the recruitment of participants, medical supervision, and compliance with a range of formal requirements. In practice, this prolongs the product launch process.
ISO 23675:2024 – a breakthrough in determining the Sun Protection Factor using the in vitro method
The introduction of ISO 23675:2024 is not merely an update to the methodology. It represents a fundamental shift in the approach to evaluating the effectiveness of sun protection. The new standard describes an in vitro method for determining the Sun Protection Factor, which allows for precise measurement without the need for human volunteers.
The test is based on the analysis of radiation transmission through a layer of the product applied to a suitable substrate simulating skin or PMMA plates, using advanced spectrophotometric techniques.
From a regulatory standpoint, this is a step toward harmonization with global trends. Increasing emphasis is being placed on:
- reducing human testing,
- enhancing the reproducibility of results and the stability of SPF values,
- and enabling the standardization of methods across laboratories.
Importantly, the in vitro method is not merely a “substitute.” It allows for better control of conditions and a thorough examination of how the filter behaves across a broad spectrum—from UVB to UVA.
Measuring UVA and UVB radiation and accurately assessing the effectiveness of cosmetics
What is most interesting about this shift, however, is not the move away from in vivo methods per se. The key point is that in vitro testing is beginning to be seen as a more operationally reliable tool.
This reverses the previous narrative. For years, methods that do not involve humans were treated as a compromise. Today, they are increasingly the first choice—not because they are “good enough,” but because they provide greater control over the outcome and allow for the precise determination of the critical wavelength and the overall efficacy of cosmetics.
SPF Values Under Control – Benefits of the New Procedure for the Cosmetics Industry
The implementation of an approach compliant with ISO 23675 (Cosmetics — Sun protection test methods — In vitro determination of sun protection factor) opens up several specific opportunities:
- Accelerated R&D: Faster assessment of UV protection efficacy as early as the formulation development stage.
- Improved comparability: Standardized conditions limit the influence of external factors on the SPF.
- Risk reduction: Consistent results are crucial for PIF documentation. Today, every sun protection product must have solid evidence to back up its claims.
It is also worth noting the communication aspect. Consumers are interested in how a given sunscreen has been tested. Information about modern tests that do not involve animals or humans is a strong marketing asset.
How to implement SPF labeling in accordance with the new in vitro method?
The biggest mistake is to view the new ISO standard solely as a technical change. It is a process that should encompass:
- R&D processes – incorporating testing at an early stage of design.
- Quality departments – updating verification procedures and recommendations for batch control.
- Regulatory affairs – aligning documentation with the ISO 23675 standard.
- Marketing – effectively communicating product safety and efficacy.
Why is the sun protection factor (SPF) measured using a non-human method the new standard?
The history of regulation shows that when a method emerges that is both more ethical and more reliable, it eventually becomes the standard. UVB and UVA radiation pose a real threat, which is why accurate measurement of protection is a priority for regulatory authorities.
ISO 23675:2024 meets all these criteria. This is not a passing trend, but a sign of the direction future market recommendations will take.
Competitive advantage in the SPF value assessment – time to implement new procedures.
The biggest difference isn’t that a particular method exists, but when we start using it. Those who master in vitro drug screening early on will gain predictability in an area that determines market success.
SPF testing methods at J.S. Hamilton – professional measurement and analysis in accordance with ISO 23675:2024.
At J.S. Hamilton Poland, we are equipped to conduct sun protection tests in accordance with ISO 23675:2024. We support manufacturers in the practical implementation of these methods—from sample requirements and measurement to the interpretation of results within the regulatory context.
If you would like to find out how the new requirements will affect your cosmetic product, please feel free to contact us.