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The In-Vitro Shift: New ISO Methods, Europe’s JACOP Results and What They Mean for Australia

Writer: Australian Sunscreen Council
Australian Sunscreen Council
11 minutes ago
5 min read

Laboratory-based SPF methods that do not burn human volunteers are now international standards, and European regulators have reported strong agreement with human testing. Dr Leslie Laquieze explains how Australian sponsors should use them today.


By Dr Leslie Laquieze, PharmD, MSc, PhD, MBA, Expert Member, Australian Sunscreen Council


For decades, SPF has been measured by deliberately inducing mild sunburn on human volunteers. That is changing. Two international standards published in December 2024 now allow SPF to be determined without causing erythema, and the evidence supporting them has strengthened through 2025 and 2026.


The two new methods

ISO 23675:2024. The International Organization for Standardization’s abstract for ISO 23675:2024 states that it “specifies a method for the in vitro determination of sun protection factor (SPF)” and is “applicable to sunscreen products in form of an emulsion or alcoholic one-phase formulation, excluding in form of a loose or compressed powder or stick.” It uses two types of roughened plastic plates, often called the “double plate” method, with robotic application of product. It does not assess water resistance.

ISO 23698:2024. The ISO abstract for ISO 23698:2024 describes “a procedure to characterize the sun protection factor (SPF), UVA protection factor (UVA-PF) and critical wavelength (CW) protection of sunscreen products without requiring biological responses.” Known as hybrid diffuse reflectance spectroscopy (HDRS), it combines a non-invasive optical measurement on skin with in-vitro plate measurements. The abstract notes that it “is applicable for emulsions and single-phase products” and “has not been evaluated for use with powder forms sunscreen products.”


The Therapeutic Goods Administration’s position

In its Advice for sunscreen sponsors and manufacturers: Acceptance of additional SPF testing information, dated 23 September 2025, the TGA said that these methods “were specifically developed to overcome the known challenges with ISO 24444,” and that “the TGA finds this evidence for the suitability of these in-vitro methods for supporting SPF indications compelling.”

The TGA noted that validation data for the methods were published in early September 2025 in the International Journal of Cosmetic Science. Among them, the ALT-SPF ring study by Kunze and colleagues, by industry and academic researchers, compared the consortium’s in-silico SPF and UVA protection factor calculations with in-vivo ISO 24444 SPF and in-vitro ISO 24443 UVA results across the ring test’s 32 formulations.

The same advice is careful about legal status. The requirement to hold AS/NZS 2604 testing “is currently imposed under Item 7 of Schedule 4 of the Therapeutic Goods Regulations 1990,” meaning sponsors “must establish the SPF for their sunscreens by testing in accordance with AS/NZS 2604 before they apply to list the sunscreen on the ARTG.” The TGA adds that this requirement “does not prevent sponsors from obtaining or holding additional evidence to substantiate the SPF of their goods, including testing using in vitro methods against ISO 23675:2024 and ISO 23698:2024,” and that the TGA “is reviewing this legislative requirement.”

The TGA’s March 2026 consultation paper on improving sunscreen regulation then set out three options: retain the status quo; allow sponsors to comply with either in-vitro or in-vivo testing where appropriate; or mandate in-vitro SPF testing only, where appropriate. The paper notes that neither new method is currently suitable for water resistance. As reported by the ABC in June 2026, the TGA told Senate estimates it had received 117 submissions and foreshadowed that it would tackle new SPF testing methods first, with labelling changes likely to take longer.


Europe’s JACOP 2025 results

On 15 September 2026, the European Commission published EU moves to more ethical sunscreen testing. Under the 2025 Joint Actions on Compliance of Products (JACOP) campaign, the SPF and UVA protection factor of 74 sunscreen products, including day creams, were tested in vitro after market surveillance authorities from 11 EU countries selected them in shops and online. The Commission reported that “the results showed a high level of correlation between in vitro and in vivo testing, which supports the reliability of the former to verify SPF claims.”

The Commission was also explicit about the limits: “the limitation of the in vitro method is that sunscreen sticks and powders cannot currently be tested,” and standardisation bodies “should work towards extending the scope of non-invasive testing methods to include these types of products, along with claims of water-resistance.” It advised manufacturers “to prioritise testing that does not cause harm to human volunteers.” The news release does not give a numerical correlation value, so the full campaign report should be examined before generalising the result to every formulation type.


Evidence and limitations for zinc oxide sunscreens

A question raised in the scientific literature was whether in-vitro methods can reliably measure sunscreens that rely on mineral filters. A 2025 study by Pissavini and colleagues in Photochemical & Photobiological Sciences, titled The double plate in vitro SPF test method (ISO23675:2024) is a reliable means of measuring the performance of sunscreen products with high concentrations of zinc oxide and inorganic-only UV filters, reports direct ISO 23675 measurements of zinc oxide sunscreens. The authors state that the method “can reliably measure the SPF of sunscreen products containing inorganic filters, even at high concentrations.” This is encouraging formulation-specific evidence, but one publication does not establish universal performance across all mineral matrices, particle characteristics or laboratories.


How to use the new methods now

Until the Australian framework formally changes, ISO 23675 and ISO 23698 should be used for:

·         formulation development and screening;

·         batch-to-batch comparison and stability monitoring;

·         independent confirmation of an in-vivo result, particularly for SPF 50+;

·         investigation of discordant results.

They should not be presented as an automatic substitute for evidence required under AS/NZS 2604. Sponsors should also note the TGA’s statement that the current framework does not prevent it “from considering this evidence or obtaining our own testing results using alternative methods, including in vitro methods.” In other words, the regulator can now check SPF claims without human testing. That alone is a strong reason to know how your products perform under these methods.

Sources

·         International Organization for Standardization, ISO 23675:2024: https://www.iso.org/standard/76616.html

·         International Organization for Standardization, ISO 23698:2024: https://www.iso.org/standard/76699.html

·         Therapeutic Goods Administration, “Advice for sunscreen sponsors and manufacturers: Acceptance of additional SPF testing information”, 23 September 2025: https://www.tga.gov.au/products/medicines/therapeutic-sunscreens/manufacturing/advice-sunscreen-sponsors-and-manufacturers-acceptance-additional-spf-testing-information

·         European Commission, “EU moves to more ethical sunscreen testing”, 15 September 2026: https://single-market-economy.ec.europa.eu/news/eu-moves-more-ethical-sunscreen-testing-2026-09-15_en

·         Pissavini M et al., Photochemical & Photobiological Sciences, 2025: https://link.springer.com/article/10.1007/s43630-025-00798-5

·         Kunze G et al., “The ALT-SPF ring study”, Int J Cosmet Sci, 2025: https://onlinelibrary.wiley.com/doi/10.1111/ics.13086


About the Author

Dr Leslie Laquieze (PharmD, MSc, PhD, MBA) is a pharmacist-scientist and international expert in sunscreen testing, photoprotection, skin pharmacology and dermocosmetic claim substantiation. An expert member of the Australian Sunscreen Council, she has led Kosmoscience Europe since 2018, supporting the evaluation, substantiation and regulatory positioning of cosmetic and dermatological products across international markets.

This article reflects the opinion of Dr Leslie Laquieze. Readers are recommended to seek expert legal advice on all issues discussed.

 
 
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