Water-based cosmetic products typically contain preservatives to prevent microbial contamination when sold in multi-use packages. Organic solvent based nail polish products (e.g. nail polish, lacquers, enamels, varnish, base coats, top coats) provide a hostile environment that prevents microbial contamination even when the product and brush are used repeatedly and therefore additional preservatives are not needed or added.
Professional use nail polish products are essentially water-free, organic solvent based mixtures of colorants, film formers and other additives. Some have questioned the use of nail polish products in salons over concerns of a possible increased risk for transmitting microbes when a polish brush is reused on multiple clients.
Several independent scientific studies, conducted by the Nail Manufacturer’s Council (NMC) of the Professional Beauty Association, demonstrate that organic solvent based nail polish products aggressively kill any microbes that may be inadvertently picked up by a nail polish brush and therefore repeated use of nail polish products does NOT pose an infection risk for salon clients.
Nail polish products used on clients in salons were collected and provided to an independent laboratory for “challenge testing”. In this test, the used nail polish products were intentionally mixed with high concentrations of seven common microorganisms associated with nail or skin infections, followed by laboratory testing to determine if any of these microbes could survive or reproduce. The products tested contain the volatile organic solvents used almost universally by all manufacturers (e.g. ethyl acetate, butyl acetate, isopropyl alcohol, etc.) which is typically 60-70% of nail polish formulation.These nail polish products were identically inoculated with a high concentration of live microorganisms, then tested immediately and periodically for fourteen (14) days to ensure there was no regrowth of microorganisms.
Results:In all of the nail polish products tested, the introduced microbes were rapidly destroyed and there was no regrowth, even after fourteen (14) days.
Study 2- Salon Nail Product Repurchase
In a second study, twenty (20) half-used nail polish bottles, representing eight commonly used salon nail polish brands, were repurchased from ten (10) nail salons. The collected nail polish containers were less than half-full, indicating they were used on approximately twenty-five (25) clients before repurchase. The collected containers were then submitted to an independent laboratory for testing.
Results: No microbes were found in any of these twenty (20) salon repurchased nail polish products.
Conclusions: Because professional-use nail polish products do not contain water as an ingredient and are mostly made of organic solvents which can rapidly destroy microbes, this explains why these products don’t require traditional cosmetic preservatives. These results demonstrate that microbes cannot live in professional nail polish products and any microbes accidentally introduced would be rapidly destroyed. These results also demonstrate that a properly used, professional-use nail polish product may be safely applied to multiple salon clients because the organic solvents are an effective deterrent against microbial contamination.
Want more details about these studies? Check out the Nail Manufacturers Council’s education brochure, “Investigation of the Potential for Microbial Contamination in Nail Polish”.