SOT FDA Colloquium: Dermal Absorption and Toxicity Basic Concepts for Application to Safety Assessment

The Society of Toxicology in conjunction with the US FDA Center for Food Safety and Applied Nutrition (CFSAN) have partnered to provide this colloquia series. The series presents scientific information that is high-quality, cutting-edge, future-oriented toxicological science to provide a well-grounded foundation to inform the work of US FDA employees.

On December 12, 2019, SOT and the US FDA hosted a colloquium that explored how different factors can affect the extent of dermal absorption such as skin structure, dermal absorption measurement techniques (in vivo and in vitro), skin metabolism, use of skin absorption kinetic modeling techniques, physio-chemical properties, mixtures, formulations and featured some case-study examples.

Dermal absorption information is needed to conduct a realistic exposure assessment for a chemical that is directly applied to skin or otherwise comes in contact with skin. If a potentially hazardous chemical/ingredient has been identified that contacts skin, then the next step in the process of safety evaluation is to estimate human exposure. Systemic exposure resulting from skin contact is a function of many different properties including the amount of chemical applied to the skin, the duration of skin contact, area of body contact, chemical physio-chemical properties and the extent of dermal absorption. If no data are available for specific exposure conditions for a chemical, then reasonable estimates of these parameters must be used. A reasonable estimate of human exposure to a topically applied chemical can be calculated if the extent of skin absorption is realistically determined.