In-Vitro

The Strategic Role of In Vitro SPF Unscreen Testing

In the fast-paced world of cosmetic development, speed, efficiency, and data-driven decision-making are paramount. In vitro SPF testing is a powerful strategic tool that empowers formulators to innovate faster, optimise with confidence, and manage R&D budgets effectively. Conducted in a controlled laboratory setting on synthetic substrates like PMMA plates, in vitro methods provide rapid, cost-effective, and highly repeatable data on a product's photoprotective performance. 

This approach allows you to screen multiple formula variations, benchmark against competitors, and refine your product's efficacy before committing to the time and expense of final clinical trials.

Our Commitment to In Vitro SPF Testing Standards

Eurofins CRL is at the forefront of SPF in vitro testing technology, offering services compliant with both established and emerging global standards. Our commitment to these methods ensures you receive the most relevant and advanced data available.

• Established Standards for UVA Protection: We are fully compliant with ISO 24443:2021, the globally accepted in vitro method for determining UVA Protection Factor (UVAPF) and Critical Wavelength. This test is the basis for the European "UVA in a circle" logo and is a key component of substantiating "Broad Spectrum" claims for the US market, making it an essential test for global formulations.
• Emerging Standards for In Vitro SPF Testing: The industry has long sought reliable alternatives to in vivo SPF testing. Representing a multi-decade effort to enhance efficiency and ethics, two new ISO standards published in 2024 mark a paradigm shift in the field. We are an early adopter of these revolutionary methods, positioning you at the cutting edge of formulation science:
  
  
  • ISO 23675:2024 (Double Plate Method): This method provides a validated in vitro SPF value by measuring UV transmission through a sunscreen film applied between two quartz plates.
  • ISO 23698:2024 (Hybrid Diffuse Reflectance Spectroscopy - HDRS): This innovative technique combines in vitro and non-invasive in vivo measurements to generate a comprehensive protection spectrum for both SPF and UVAPF calculation.
    These new standards provide a validated, rapid, and ethical alternative for obtaining SPF data during R&D and for quality control, enabling a more agile and iterative development process.
    
    

In Vitro SPF Testing Methodologies and Technologies

Our SPF testing laboratory utilises advanced instrumentation and proven methodologies to deliver precise and actionable results.

• Spectrophotometric Analysis: At the core of our in vitro testing is the use of high-precision spectrophotometers equipped with integrating spheres. This technology allows us to accurately measure the total amount of UVA and UVB radiation transmitted through the sunscreen film.
• PMMA Plate Substrate Testing: To ensure consistency, we apply the test product to Polymethyl methacrylate (PMMA) plates. These plates are specifically roughened to mimic the surface topography of human skin, promoting a more uniform and realistic product film for analysis.
• Critical Wavelength Determination: For brands targeting the US market, we perform the Critical Wavelength test. This analysis determines the wavelength at which the sunscreen has absorbed 90% of UV light, ensuring it meets the FDA's  SPF testing requirement of 370 nm or greater for a "Broad Spectrum" claim.
  
  

Applications of In Vitro Testing in the Product Lifecycle

In vitro sunscreen testing is a versatile tool that provides critical data at multiple points in the development cycle.

• Early Formulation Screening: Rapidly and cost-effectively compare the performance of dozens of formula variations, different UV filter combinations, or new raw materials to identify the most promising candidates for further development.
• Competitive Benchmarking: Objectively measure your prototype's UV protection profile against leading products on the market to ensure your formulation is competitive and differentiated.
• Stability and Shelf-Life Assessment: Evaluate how a product's photoprotective capabilities hold up over time and after exposure to heat or light, providing crucial data for stability protocols.
• Claim Substantiation Support: Generate the foundational data required to support key marketing claims such as Broad Spectrum protection, UVA protection, and Blue Light protection.
  
  

Key Benefits of In Vitro Testing

• Cost and Time Efficiency: Receive actionable data in days, not weeks, at a fraction of the cost of a full clinical trial, accelerating your R&D timeline.
• Ethical Considerations: This methodology completely eliminates the need for human or animal subjects during the formulation and screening phases of development.
• Repeatability and Precision: Highly controlled laboratory conditions minimise variability, yielding precise and reproducible data that is ideal for making direct comparisons between different formulas.
• Formulation Optimisation: Enable an iterative, data-driven approach to perfecting your product, allowing you to fine-tune UV filter levels and optimise cosmetic elegance before final validation.
  
  

Specialised In Vitro Services

Beyond standard SPF testing methods and UVA testing, we offer a range of specialised in vitro services to meet the demands of the modern sun care market.

• Photostability Assessment: A critical test that evaluates whether a formula's protective capabilities degrade upon exposure to UV light, ensuring its efficacy is maintained during real-world use.
• Broad Spectrum Protection Evaluation: Our core service for assessing a product's performance across the entire UV spectrum, compliant with ISO 24443 and FDA requirements.
• Blue Light Protection Testing: Address the growing consumer demand for protection from High-Energy Visible (HEV) light, emitted by electronic screens and the sun, which is linked to premature ageing.
• In Vitro Phototoxicity Screening (3T3 NRU): We offer the globally recognised gold standard for early safety screening, the 3T3 Neutral Red Uptake Phototoxicity Test (OECD Test Guideline 432), to assess the potential for ingredients to cause photoirritation.
  
  

Understanding In Vitro Test Results

Our expert team provides detailed reports that clearly explain key metrics like UVAPF, Critical Wavelength, and in vitro SPF. It is important to understand the role of this data: in vitro results are highly predictive and provide excellent directional guidance for your R&D program. However, due to the complex nature of how a formula interacts with living skin, in vivo testing remains the final arbiter for substantiating a definitive, on-pack SPF claim for regulatory purposes. Our experts can help you understand the correlation between the two methods and design a testing strategy that leverages the strengths of both.

FAQS

Q1. How does ISO 24443 in vitro testing help in determining UVA protection in sunscreens?

ISO 24443 is the globally recognised in vitro testing standard for UVA Protection Factor (UVAPF), a critical measurement for substantiating broad-spectrum claims in sunscreens. This method determines the UVAPF value, which quantifies a sunscreen’s ability to block UVA radiation. A higher UVAPF indicates better protection against UVA, the rays responsible for premature skin ageing and deeper skin damage.

In addition to UVAPF, ISO 24443 also measures Critical Wavelength, which tells you the wavelength at which the sunscreen absorbs 90% of the UV radiation, a requirement for broad-spectrum claims in the U.S. market. This makes ISO 24443 essential for ensuring that your product can make the necessary UVA protection claims both in Europe (for the "UVA in a circle" logo) and international markets.

Q2. What role does in vitro testing play in early-stage sunscreen formulation?

In vitro testing plays a crucial role in the early-stage screening and optimisation of sunscreen formulations. Unlike in vivo testing, which requires human participants and is more time-consuming, in vitro testing provides rapid results that help formulate sunscreens efficiently.

Here are some key benefits:

• Fast R&D Screening: Quickly assess multiple formula variations, UV filter combinations, or new ingredients to determine their effectiveness in blocking UV rays.
• Cost-Effective: In vitro testing is less expensive than clinical trials, enabling brands to compare formulas without significant financial commitment.

Consistency and Precision: Controlled lab environments with synthetic substrates (like PMMA plates) ensure highly repeatable results that allow for precise adjustments to formulations.

Q3. Can in vitro testing for Blue Light Protection be part of the sunscreen development process?

Yes, blue light protection is increasingly becoming an important claim for sunscreen products, especially with growing consumer awareness of high-energy visible (HEV) light emitted from electronic screens and the sun. In vitro testing can effectively assess the effectiveness of sunscreens against blue light exposure.

Eurofins CRL offers Blue Light Protection Testing, which measures how well a sunscreen formulation shields the skin from the harmful effects of HEV light. This test is particularly relevant for modern consumers looking for additional protection beyond UV radiation, helping you position your product as multi-functional in a competitive market.

This testing ensures that your sunscreen not only protects against UV radiation but also offers a more comprehensive defence against other environmental stressors like blue light, meeting a growing market demand.

Contact Our In Vitro Testing Experts

Accelerate your R&D and optimise your next formulation. Contact our technical experts to discuss an in vitro screening program tailored to your project goals.