Reducing allergens: New multifunctional preservatives gain ground in baby cosmetics

19 Aug 2024 --- A new study in Scientific Reporting reveals a shift in the cosmetics industry, particularly in replacing conventional preservatives with multifunctional antimicrobial ingredients for infant and sensitive skin products. The researchers believe preservatives are the “most prevalent contact allergens in cosmetics for babies and children.” 

Traditional preservatives, which have long been used to prevent microbial contamination in cosmetics, are gradually being replaced or supplemented with multifunctional ingredients. According to the study, the change is driven by the need to reduce allergic contact dermatitis (ACD) and other skin sensitivities while maintaining product safety.

The researchers explain: “Infant skin also consists of reduced thickness of stratum corneum and smaller corneocytes compared to those of adult skin, which also facilitates transdermal absorption of environmental allergens. However, investigative studies have suggested that nearly 90% of cosmetics for babies and children contain at least one contact allergen, which may pose major concern for ACD in babies and children.”

They reviewed cosmetics available on the Chinese market and identified seven traditional preservatives (phenoxyethanol, benzoic acid (salts), methylparaben, benzyl alcohol, sorbic acid (salts), propylparaben and methylisothiazolinone) and eleven alternative ingredients with antimicrobial properties. 

The study sees a trend toward safer and more natural preservatives aligned with consumer demand for “green,” “natural” and “paraben-free” cosmetics. 

However, researchers warn that, despite these claims, the actual content of preservatives and multifunctional ingredients in cosmetics needs careful monitoring. The industry may also need to consider the long-term safety of these alternatives, particularly as their use becomes more widespread.

Ethylhexylglycerin and caprylyl glycol are leading alternatives to traditional preservatives in sensitive skin products.Popular alternatives

Traditional preservatives remained common, particularly in products for infants. However, alternatives like ethylhexylglycerin, caprylyl glycol and p-anisic acid are becoming more prevalent, especially in products for sensitive skin. 

Researchers detected other alternatives: butylene glycol, propylene glycol, 1,2-hexanediol, hydroxyacetophenone, pentylene glycol, decylene glycol, caprylhydroxamic acid and aminomethyl propanol.

They collected 83 products, of which 70 were for infants and 13 were claimed to be suitable for sensitive skin. The 70 products consisted of 28 moisturizers, six nappy creams, 16 sunscreen creams, six anti-itch gels, four shampoos, five body washes and five two-in-one hair and body washes. Regarding products for sensitive skin, 12 out of 13 products were face creams and the other one was sunscreen cream.

Twenty-three baby products and two sensitive skin products contained ethylhexylglycerin, which is known to increase the effects of preservatives. Researchers say it is often used in combination with other preservatives to enhance antimicrobial efficacy. 

Researchers say caprylyl glycol, another multifunctional ingredient, is becoming more popular, due to its strong antibacterial profile and safety. 

However, the study notes that even with these alternatives, preservative efficacy could be compromised under certain conditions, emphasizing the importance of careful formulation.

Researchers state that “multifunctional ingredients with antimicrobial properties in cosmetics have the potential to completely replace or significantly reduce the use of traditional preservatives while retaining comparative preservative efficacy.”

Even with new ingredients, factors like pH and storage conditions are critical to preserving product safety.Preservation problems

The study discovered that traditional preservatives still dominate baby cosmetics, despite the trend toward multifunctional ingredients. For example, phenoxyethanol was the most commonly used preservative, presumably chosen for its safety and effectiveness. 

Interestingly, while some preservatives, such as formaldehyde releasers and isothiazolinones, were absent from the products tested, researchers detected parabens in some of them, despite their controversial status.

“Conventional preservatives are typically electrophiles with low molecular weight, which potentiates them to interact with and cause sensitization in the skin. In fact, preservatives have constituted one of the most common causes of ACD attributed to the use of cosmetic products,” say researchers.

“Therefore, to reduce the incidence of ACD, the use of single high-concentration conventional preservatives has been gradually replaced with combinations of various low-concentration preservatives without compromising the preservative efficacy.”

They add: “In addition to optimizing the use of conventional preservatives, the cosmetic industry has also been repurposing artificially synthesized multifunctional ingredients with antimicrobial properties, which are not currently legislated as preservatives, for preservation use.”

“For example, glycols have been increasingly used as antimicrobial agents in addition to its role as humectants based on their emulsifier-like structure, which can disrupt the cellular integrity of microorganisms.”

Researchers note the addition of several botanical-derived ingredients to cosmetic preparations as skin-conditioning agents, which has shown strong antimicrobial properties.

The study emphasizes that although multifunctional ingredients present a viable substitute, they are not exempt from challenges. Factors such as pH levels, storage conditions and interactions with other ingredients can impact preservative efficacy. 

Moreover, researchers underscore that even ingredients considered to have low allergenic potential, like phenoxyethanol and organic acids, must be used within strict concentration limits to avoid adverse skin reactions.

By Venya Patel