Hormesis [biological effects of low-level exposure (B.E.L.L.E.)] and dermatology.
Hormesis is characterized by nonmonotonic dose response that is biphasic, displaying opposite effects at low and high doses. Its occurrence has been documented across a broad range of biological models and diverse types of exposure. The effects of hormesis at various points can be beneficial or detrimental, depending on the context in which they occur. Because hormesis appears to be a relatively common phenomenon in many areas, the objective of this review is to explore its occurrence related to dermatology and its public health and risk assessment implication. Hormesis appears to be a common phenomenon in dermatology. Better understanding of this phenomenon will likely lead to different strategies for risk assessment process employed in the fields of dermatologic toxicology and pharmacology. More focus should be redirect from looking only at adverse effects at high levels of exposure to characterizing the complex biological effects, both adverse and beneficial, at low levels of exposure. Low-dose toxicology and pharmacology will not only provide a significant research challenge but also should contribute to better methods for low-dose risk assessment for complex mixtures of chemical compounds. This refocusing from high- to low-dose effects will shift the focus in the field of toxicology from emphasizing on adverse effects into studying the biological effects of chemical compounds on living organisms, taking into account the realization that the ultimate biological effect of a chemical may vary with its dose, the endpoint, the target organ considered, the interaction with other cell types/systems, and/or the combined exposure with other chemicals. The skin, with its ready accessibility, and its own areas of non-invasive technology, should provide fertile options to not only understand skin, but further explore practical implications in human and animal. We believe that hormesis is a common phenomenon and should be given detailed consideration to its concept and its risk assessment implications, and how these may be incorporated into the experimental and regulatory processes in dermatology. The skin, with its unique characteristics, its accessibility, and the availability of non-invasive bioengineering and DNA microarray technology, will be a good candidate to extend the biology of hormesis.
Thong
Haw-Yueh
HY
Department of Dermatology, University of California, School of Medicine, San Francisco, California 94143-0989, USA.
Maibach
Howard I
HI
D000818:Animals; D003880:Dermatology; D004305:Dose-Response Relationship, Drug; D064420:Drug-Related Side Effects and Adverse Reactions; D006801:Humans; D012871:Skin Diseases / Q000139:chemically induced*