Safety Considerations For Baby Care Products

To bring safe baby cosmetics on the market, risk assessment is a key priority and often includes a broadly recognized iterative four-step quantitative exposure-based risk assessment process (US National Academy of Sciences, WHO and the European Union’s Society Scientific Committee on Consumer Safety and Bureau of Indian Standards IS 4011:2018.

The potential impact of skin irritation on dermal absorption should be taken into consideration during baby cosmetic product development.

A distinction should be made between intact, healthy skin and the potentially damaged skin of the nappy zone for which risk factors exist, which are not present for the rest of the body.

The increased prevalence of allergic contact dermatitis in children has prompted scrutiny of products marketed for neonates and children for the presence of sanitisers.

Criteria

During the development of baby products, a number of criteria should be taken into consideration:

High quality of raw materials in terms of purity, stability, and microbiology via appropriate Certificate of Analysis (CoA).
Skin Irritation, which is dose-dependent, can be controlled by avoiding well-known irritative ingredients and/or reducing the concentration or frequency of application.
The presence of sanitizing molecules such as perfume ingredients, even when IFRA (International Fragrance Association) – tested and/or excluding the 26 allergens taken up in regulations, should be avoided if they are not found to be safe.
The product information file of baby cosmetics, safety data of all ingredients and the finished product, together with a dedicated risk assessment, carried out by a safety assessor, should be present. It should be indicated what specific measures have been taken for baby skin.
Special attention should be given to the concentration of (i) reactive substances (ii) promotional additives, ‘natural’ and ‘exotic’ ingredients, complex mixtures, plant extracts and animal-derived ingredients or any ingredient from a questionable, impure source; (iii) potential allergens, penetration enhancers, aggressive organic solvents, highly detersive or foaming agents, and antiseptics in particular in daily use products; and (iv) concentrations of preservatives.
Good practice is: (i) to protect unsaturated lipids from oxidative reactions by adding anti-oxidants; (ii) to adjust and buffer the pH of the final product to skin-friendly pH between 4.5 and 6; (iii) to add chelating or sequestering agents to prevent heavy metal precipitation and protect the preservative system; and (iv) to use known protective skin barrier ingredients.

Dermal Absorption

Dermal absorption data is compound-dependent, varying molecular weight, hydrophobicity
| hydrophilicity, structure, etc., and frequently determined using adult skin.

The surface area | body weight ratio is 2.3-fold higher in newborns than in adults decreasing to 1.8-fold at 6 and 12 months, respectively. Application of the same amount of product on a similar body surface of baby versus adult could result in higher blood and tissue concentrations in the newborn.
Pharmacokinetic parameters differ widely between babies and adults and result in reduced clearance and/or a longer half-life of bioavailable substances, thus increasing the potential risk for adverse reactions in babies. Concerning the total body water content, it is known that infants have a higher water content (80-90%) compared to those of adults, which steadily decreases to 55-60%

Another pharmacokinetic difference is a decreased protein binding capacity which can be linked to lower concentrations of glycoproteins in the plasma of infants.

Full-term neonates, tend to show a three to nine times longer pharmacokinetic half-life than adults.

The SC thickness is reported to be the rate limiting part for percutaneous penetration and thus dermal absorption. The SC is thinner in baby versus adult skin, as measured by confocal laser scanning microscopy, and needs to be considered. The path that molecules have to follow to penetrate the SC layer is potentially shorter.

Importantly, the SC’s barrier is functional at birth and matures for many key skin characteristics (skin pH) in the first few months after birth.

In use conditions of topical products also play a role. Cosmetic skin care products often are applied onto large body surfaces, e.g., cleansing lotions, sunscreens, etc., increasing not only the potential risk for local effects but also dermal absorption and potential systemic toxicity. This factor is considered in exposure-based risk assessments.
The Diaper Area and non-diapered regions are indistinguishable at birth but show differential behavior over the first 14 days, with the diapered region having a higher pH and increased hydration. Innovative hygiene absorbent and baby care products, however, provide an increasingly good skin compatibility profile, making the frequency and severity of DD decline.
Other important factors for dermal absorption are SC hydration and skin pH. For instance, differences in skin pH change the ionization grade of molecules and will influence dermal absorption.

Bibliography

Susanna Brink, M. O. (2023). Baby Care Products. In E. J. Frank Dreher, Handbook of Cosmetic Science and Technology (pp. 339-340). Boca Raton, FL: CRC Press.