Assessing the dermal safety of products intended for genital mucosal exposure

Manufacturers employ a stepwise approach to ensure the skin safety and compatibility of consumer products that are intended for contact with mucosal skin. The properties of the ingredients are evaluated fully, along with any available safety and skin compatibility information, to eliminate any chemicals that may be strong contact sensitizers or irritants. Contact sensitization potential is evaluated by applying a quantitative exposure assessment to each ingredient or component to determine if the extent of the expected exposure is likely to pose any risk of contact sensitization. Likely exposures are calculated using the manufacturer's unique knowledge of the intended product matrix, consumer usage patterns and measurements of particular exposure variables. If adequate safety assurance cannot be provided, further testing may be conducted. The skin compatibility and irritation potential of each ingredient is evaluated using existing test data, and experience from other products containing the same or a structurally similar ingredient. Once a finished product or formulation is developed, another round of assessments is conducted to ensure that no unexpected matrix effects negatively impact the skin compatibility profile. This may include clinical testing protocols involving single and multiple patch tests, and extended use testing, with visual and/or instrumental assessments. This approach to ensuring the skin safety of products has been used successfully for many decades, and adverse skin reactions to modern products are rare. The challenge for the future is to develop test protocols that will discriminate between products that are very similar in their favorable skin compatibility profile. Options to meet this challenge include testing protocols that will: (1) further exaggerate exposure conditions, such as the behind-the-knee protocol, (2) increase the sensitivity of scoring for irritant effects, such as with the use of instrumentation, and (3) quantitatively measuring additional endpoints, such as subjective sensory effects.