In the world of personal care formulation, the “natural” trend has pushed many R&D teams to move away from traditional, broad-spectrum preservative systems. However, a recent FDA Warning Letter (Reference #690184) and subsequent class-action filings involving a major natural oral care brand serve as a critical reminder: Hurdle technology is only as strong as your weakest GMP link.
As formulators, we have a responsibility to look past the headlines and analyze the technical failures cited by regulatory bodies to ensure our own systems are robust.
The Findings: Specific Pathogens in the Spotlight
According to the FDA inspection reports, several high-risk microorganisms were detected within the manufacturing environment and finished products:
- Ralstonia insidiosa: Found in the purified water system. This bacterium is a known “oligotroph” and an expert at forming biofilms in water loops, making it incredibly difficult to eradicate with standard sanitization.
- Pseudomonas aeruginosa: Detected in specific mouthwash batches. As an opportunistic pathogen, its presence in a personal care product is a significant safety concern, especially for vulnerable populations.
- Paracoccus yeei: Also identified within the facility’s water system.
The Formulation Audit: Why Hurdles Fail
The products in question, such as the Antiplaque & Whitening Toothpaste, often rely on a combination of ingredients to inhibit microbial growth rather than eliminating it via bactericidal activity.
The formula typically includes:
- Calcium Carbonate & Sodium Bicarbonate: Abrasives that also influence pH.
- Glycerin & Xylitol: Humectants used to lower Water Activity
- Zinc Citrate: An active with known bacteriostatic properties.
- Sodium Lauryl Sulfate (SLS): A surfactant that can disrupt some bacterial cell membranes.
The Technical Gap:
While these “hurdles” are effective against common oral flora, they may not be enough to suppress a high initial bio-burden. If the manufacturing water is already compromised with biofilm-forming bacteria like Ralstonia, the preservative “safety net” can be overwhelmed before the product is even packaged.
GMP: The Ultimate Preservative
The most striking takeaway from the FDA’s report was the failure to adequately investigate Out-of-Specification (OOS) results. The letter alleges that microbial excursions in the water system were noted as early as 2021, yet production continued.
For formulators and quality managers, the lesson is clear: You cannot “preserve” your way out of a contaminated facility. A robust preservative system is designed to handle incidental contamination during consumer use—not to sterilize a product made with contaminated water.
Best Practices for Formulators
To mitigate these risks in your own projects, consider the following technical safeguards:
- Validate Water Loops Periodically
- Challenge Testing (PET)
- Measure the water activity
Conclusion
The current litigation serves as a cautionary tale for the industry. It highlights that the move toward “cleaner” labels must be matched by even more rigorous manufacturing standards and microbial monitoring.
The GreenChemFinder compendium contains ingredients that support Hurdle technology as well as a bactericidal approach
Disclaimer: Always include a footer stating: “This post is for educational purposes and reflects the author’s technical opinion based on public regulatory filings. It does not constitute legal or regulatory advice.”