Historically, most cosmetic products were water-based and relied on standard preservatives, making safety testing relatively straightforward. Today, formulations are increasingly complex. Recent innovations, such as probiotic skincare, waterless formats, and made-in-store cosmetics, are introducing new risks and outpacing existing regulatory guidance.
These shifts have implications not only for finished formulations but for new product development (NPD) too.
ISO 29621 offers a solid foundation for assessing microbial risk but it’s not enough on its own. Brands need to adopt evidence-led, risk-based approaches tailored to their specific formulations and reflective of real-world use, not just lab conditions. Failure to do so may result in product recalls, financial loss, and significant brand damage, including a breakdown in consumer trust.
Ben Elmadi, technical manager – cosmetics at MSL Solution Providers, comments: ‘With manufacturing lines being moved into stores and over 150 product variants offered from just 10 core ingredients, microbial safety is no longer a one-size-fits-all equation. Add to that probiotic formulas, which introduce intentional microorganisms, and the rise of sustainable “just add water” products – technically exempt from challenge testing since they are anhydrous, but where rehydration introduces risk – and the cracks in existing testing protocols are clear.
‘Relying solely on outdated standards leaves gaps that brands can’t afford to ignore. ISO 29621 offers a smarter, risk-based framework, but it’s only effective when paired with expert oversight and real-world evidence.’
As microbiological testing and regulatory experts, MSL works with brands to tailor testing plans, navigate emerging formats, and stay ahead of evolving regulatory expectations. It recommends taking a proactive, evidence-led approach to microbial safety that:
- Reassesses product risk using ISO 29621 as a strategic foundation.
- Avoids blanket testing protocols that overlook formulation nuance.
- Ensures testing reflects how products are actually used, not just how they perform in controlled lab conditions.
MSL Solution Providers is one of the UK’s leading regulatory and laboratory testing houses. Its in-house accredited labs provide a comprehensive range of standard tests, including challenge preservative efficacy testing (PET) stability testing, pack performance and compatibility testing. It also offers consultancy, training and GMP services, supporting SMEs to blue chip cosmetic manufacturers and brands internationally.
For further information, visit www.msl.io
