In the dynamic world of cosmetic science, the pursuit of product efficacy while ensuring stability is a significant challenge. With summer here, consumer groups often raise concerns about the performance of sunscreens and other products, highlighting the discrepancies between physical and chemical stability versus biochemical instability.
This month’s column dives into these complex stability issues, offering actionable solutions and advocating for more rigorous, transparent testing methods to foster trust across the cosmetic industry.
Understanding the Stability Spectrum
Cosmetic products are meticulously designed to remain stable under various conditions:
Physical Stability: Observes changes in appearance, color, odor, texture, and phase separation.
Chemical Stability: Monitors the concentration of active ingredients and potential degradation products.
Microbiological Stability: Ensures the product remains free from microbial contamination over time.
Packaging Compatibility: Assesses interactions between the formulation and its packaging, including potential leaching or absorption of ingredients.
Despite thorough testing, biochemical instability can occur, diminishing efficacy due to the degradation of active compounds from environmental factors or interactions within the product matrix, without any affect on physical stability.
Consumer Group Findings: A Wake-Up Call?
Consumer groups like Which? and Stiftung Warentest have spotlighted performance issues, revealing gaps between lab results and real-world application. These discrepancies suggest a need for enhanced testing methods to ensure products perform consistently on the skin.
Regulatory Compliance vs. Biochemical Stability
While the EU Cosmetic Regulation mandates thorough stability testing to ensure safety, it often overlooks biochemical stability. This gap can affect product efficacy, underscoring the need for tests that address subtle biochemical changes.
Efficacy Testing: Fully Stabilised Formulations vs. Pilot Batches
Pros of Testing Fully Stabilised Formulations:
Accurate Representation: Reflects true performance as experienced by consumers.
Regulatory Confidence: Enhances credibility in claims substantiation.
Long-term Performance: Ensures effectiveness throughout the product’s shelf life.
Pros of Testing Pilot Batches:
Speed to Market: Accelerates product development.
Cost-Effective: Reduces initial testing costs for small or start-up companies.
Cons of Each Approach:
Fully Stabilised Formulations: Time-consuming and costly.
Pilot Batches: Potential inaccuracies and regulatory risks.
Bridging the Gap: Proactive Solutions
1. Comprehensive Stability Testing: Incorporate physical and biochemical stability tests to provide a complete picture of product stability.
2. Advanced Formulation Techniques: Use encapsulation or stabilising agents to protect sensitive ingredients from degradation.
3. Iterative Testing: Conduct stability and efficacy tests throughout development, integrating real-world usage scenarios.
4. Real-time and Accelerated Testing: Combine methods for quicker insights into long-term stability.
5. Collaborative Approach: Work closely with suppliers and packaging manufacturers to identify and address stability issues early.
6. Consumer Education: Educate consumers on proper storage and usage to maintain product efficacy.
7. Scrutinising Consumer Group Testing: Advocate for transparency and standardisation in consumer testing methods.
8. Collaborative Transparency: Encourage open dialogue between scientists, regulatory bodies, and consumer groups to refine and harmonise methodologies and share data.
Impact on Cosmetic Claims and Compliance
Addressing the discrepancies between stability and efficacy has direct implications for cosmetic claims and compliance. By enhancing testing protocols and formulations, we can support robust, real-world claims, ensure regulatory compliance, and build consumer trust.
Theresa Callaghan
Theresa Callaghan, a PhD biochemist with over 35 years of experience in corporate skin care research, has held key R&D senior roles for companies including LVMH, Unilever, Marks & Spencer, J&J, Evonik, Hill-Top Research, and proDERM. In 2008, she created Callaghan Consulting International, focusing on cosmetic claims development with brands and ingredient suppliers. She is a widely published author, frequent speaker, and contributor to peer-reviewed journals. Her acclaimed book, 'Help! I'm Covered in Adjectives: Cosmetic Claims & The Consumer', has gained popularity. She is a member of the Society of Cosmetic Scientists and British Herbal Medicine Association, and has lectured at the University of Sunderland's School of Pharmacy and Cosmetic Sciences. Theresa serves on the editorial peer review board of the International Journal of Cosmetic Science. She also mentors and has her own Cosmetic Claims Insights Column with EuroCosmetics.
