Dermal safety assessment of Arm & Hammer laundry products formulated for sensitive skin

Safety-in-use test of facial cosmetic products on normal and self-assessed sensitive skin subjects

BACKGROUND

Safety-in-use (SIU) studies are commonly used by the cosmetic Industry to confirm the skin and ocular compatibility of cosmetic products under realistic in-use conditions. There are only limited case studies published about the design, outcome and interpretation of product SIU studies.

OBJECTIVE

A series of SIU case studies is presented to demonstrate the considerations in study design and how the methodology can help in supporting skin and ocular safety profile of facial cosmetic products within a population of different ethnicities with normal and self-perceived sensitive skin.

SUBJECTS/METHODS

In a series of four single-blinded SIU studies, more than 250 female study subjects of different ethnicities and with normal and self-assessed sensitive skin were asked to use different facial cosmetic products including lotions, essences and cleansers according to the instructed usage conditions of these products. Each study was specifically designed according to product usage scenarios and target consumer groups. The primary measures of safety were based on dermal evaluations by a dermatologist for erythema and dryness/scaling and by an ophthalmologist for any visible signs of an ocular condition on eyelids, conjunctivae and cornea. The study subjects were also asked for any self-perceived skin or eye reactions. Dermal and ocular irritation potential of the products under realistic product usage conditions was evaluated according to the measures.

RESULTS

Across all studies, objectively and self-assessed mean scores for skin and eye effects did not indicate any cumulative response of the investigated products over the study period.

CONCLUSIONS

As a suitable tool for assessing and establishing the skin and eye compatibility of facial cosmetic products, SIU studies can be designed according to specific consumer groups, skin types and product usage scenarios to better predict realistic in-use conditions. It can demonstrate the safe use of the investigated products for people of different ethnicities, skin types and with normal or self-assessed sensitive skin, single product use or regimen use. The test results are consistent with the inherently low irritation potential of the products.

The 21-day cumulative irritation assay in man: a half-century summary and re-evaluation

The 21-day cumulative irritation test (21-day CIT) has been widely used in dermatopharmacology and dermatotoxicology to assess the irritation potential of topical products. Since described by Lanman in 1968, it has been modified, shortened, re-evaluated, and statistically analysed by multiple groups of authors. As the assay has been recommended in FDA draft guidance, we bring subsequent experience to date. The shorter 14-day version is commonly used and may be as adequate as the 21-day application when used to discriminate between moderate to strong irritants. While previous authors stopped the test when subjects experienced an irritation score of 3 or more, the FDA suggested moving the test to another anatomical site to complete in 21 days. This approach avoids assumptions, thus may be more accurate to quantify skin irritation. As the scoring is based on visual grading, the 21-day CIT also does not account for sensory irritation. Therefore, future studies need to propose a way to evaluate the sensation objectively in dermatological product development.