I am pleased to inform you that my lecture at the Dermal Toxicology Specialty Section of SOT recording is available for viewing. The link: Dermal Toxicology Specialty Section | SOT should bring you to it if you missed it.
Dermal Absorption And Toxicology In Vitro; What Are The Tests, How Can We Use Them And Where Are The Innovations?
Abstract: Dermal absorption and toxicology in vitro; what are the tests, how can we use them and where are the innovations? Some of the earliest toxicology tests were developed to identify topical hazards (e.g., the Dermal Draize test and the Guinea Pig Maximisation test). There have been many years of development of new assays to create more human relevant data. For example, skin absorption has been evaluated in the human skin since the 1960s using the Franz diffusion cell resulting in regulatory acceptance by FDA, EPA, and the European Agencies, particularly after the creation of the OECD 428 in 2004. There has been a plethora of dermal toxicology tests developed to identify acute toxicity outcomes such as using the EpiDerm 3D model for skin irritation (OECD 439) and corrosion (OECD 431) to replace the Draize irritation tests or the 3T3-NRU (OECD 432) to screen and often replace phototoxicity testing. The road to replacement of the skin sensitization animal tests (including the LLNA) has been slower due to the complexity of this disease to model. However, in 2021, a defined approach for skin sensitization was published (OCED 497) and this identifies the different testing required including the DPRA, KeratinoSens™, h-CLAT assays. This seems to have resolved the acute testing needs, but where can there be further innovation? The skin irritation test (OECD 439) is only suitable for chemicals and not formulations and mixtures and is of particular interest for resolution by US EPA. What about more chronic questions? The skin absorption test (OECD 428) has been extensively used for 24 h, but the rat in vivo test is used up to 168 h, can this in vitro test system be used for longer time periods in regulatory toxicology? How can further innovations take place against the concerns about the lack of human relevance of the current animal tests?