Heidi P. Chan

Cutaneous bioengineering instrumentation standardization: the Tissue Viability Imager

Background: Tissue Viability Imaging (TiVi) is a new bioengineering technology intended for remote two‐dimensional mapping of skin red blood cell concentration (RBCconc). Before use in the laboratory, work‐site and dermatology clinic, critical performance parameters of this emerging technology require careful evaluation.

Comparison of tissue viability imaging and colorimetry: skin blanching.

Background: Operator‐independent assessment of skin blanching is important in the development and evaluation of topically applied steroids. Spectroscopic instruments based on hand‐held probes, however, include elements of operator dependence such as difference in applied pressure and probe misalignment, while laser Doppler‐based methods are better suited for demonstration of skin vasodilatation than for vasoconstriction.

Skin decontamination: principles and perspectives

Skin decontamination is the primary intervention needed in chemical, biological and radiological exposures, involving immediate removal of the contaminant from the skin performed in the most efficient way. The most readily available decontamination system on a practical basis is washing with soap and water or water only. Timely use of flushing with copious amounts of water may physically remove the contaminant. However, this traditional method may not be completely effective, and contaminants left on the skin after traditional washing procedures can have toxic consequences. This article focuses on the principles and practices of skin decontamination.

Tissue viability imaging: mapping skin erythema.

Background: Tissue Viability Imaging (TiVi) is an emerging bioengineering technology intended for two‐dimensional mapping of skin erythema and blanching. Before TiVi can be effectively used in studies of diseased or damaged skin, the variability in normal skin red blood cell concentration (RBCconc) requires evaluation.

Chondrodermatitis nodularis chronica helicis in monozygotic twins

Chondrodermatitis nodularis chronica helicis (CNCH) is a benign inflammatory nodule of the helix. Patients report severe tenderness upon pressure. Commonly seen in middle‐aged men, there are no reports of this disease in twins. We report middle‐aged male monozygotic twins who simultaneously developed CNCH. This suggests, but does not prove, the possibility of a hereditary factor in the pathogenesis of CNCH.

Skin decontamination of glyphosate from human skin in vitro.

This study compared three model decontaminant solutions (tap water, isotonic saline, and hypertonic saline) for their ability to remove a model herbicide (glyphosate) from an in vitro human skin model. Human cadaver skin was dosed (approximately 375microg) of [14C]-glyphosate on 3cm2 per skin. After each exposure time (1, 3, and 30min post-dosing, respectively), the surface skin was washed three times (4ml per time) with each solution. After washing, the skin was stripped twice with tape discs. Lastly, the wash solutions, strippings, receptor fluid, and remainder of skin were liquid scintillation analyzer counted to determine the amount of glyphosate. There were no statistical differences among these groups at any time points. The total mass balance recovery at three time exposure points was between 94.8% and 102.4%. The wash off rates (glyphosate in wash solutions) at three different exposure times is 79-101.2%. Thus the three tested decontaminants possess similar effectiveness in removing glyphosate from skin. This in vitro model is not only economic and rapid, but also provides quantitative data that may aid screening for optimal decontaminants.

Hair highlights and severe acute irritant dermatitis ("burn") of the scalp

Context: These days, most celebrities—young and old—have their hair highlighted. That is why it is not surprising that even the youth have their hair highlighted as they emulate their favorite actors, unaware of the harmful consequences of this unsafe procedure. Hair highlighting involves decolorizing melanin pigments of select hair strands through an oxidation reaction under alkaline conditions by the active ingredients of the highlighting mixture—hydrogen peroxide, persulfates, and metasilicate. Hydrogen peroxide and the persulfates are flammable, necessitating that regulatory bodies (namely, the U.S. Food and Drug Administration [FDA] and the Cosmetic Ingredient Review [CIR] Expert Panel, the European Union’s (EU), European Economic Community [EEC] directives, the Australian government’s National Industrial Chemicals Notification and Assessment Scheme [NICNAS], and the Association of Southeast Asian Nations [ASEAN]) to regulate the permissible amounts of these chemicals in hair highlighting products. Objectives: To review published case reports of resulting in severe acute irritant dermatitis (“burns”) of the scalp caused by hair highlighting, to explain why these scalp burns happen, to identify preventive measures to avoid such occurrences, and to discuss the implications for society. Materials and methods: We searched medical and scientific search engines and used keywords such as hair highlights, scalp burn, and other related terms.. Results: Six articles were obtained, yielding 8 reported cases (2 of the 6 articles had 2 cases each) of hair highlighting resulting in scalp burns; these 8 cases were reviewed and analyzed. Five of the 8 patients belonged to the pediatric age group. Discussion: The causes of scalp burn were classified into 2 categories: chemical (caustic nature of the highlighting mixture, spillage of the hot mixture, toxic reaction to the dyes) and thermal (by contact of the scalp with overheated aluminum foil and by the blow dryer). The 5 pediatric patients in the group unnecessarily suffered pain and embarrassment caused by this procedure, as well as the risk of developing malignancy in the future. Conclusions: Hairstylists play a large role in the occurrence of scalp burns. Thus, they need to be careful and knowledgeable of the caustic nature of the highlighting mixture and the potential harm these chemicals may cause. The authors strongly propose that the relevant regulatory bodies review the permissible levels of the caustic chemicals, and that this unsafe procedure should be performed only on adults.

Measuring human skin buffering capacity: an in vitro model

Background/purpose: It has been thought that skin possesses buffering capacity. This study measured the skin buffering capacity against two model solutions of acid and base at three concentrations with an in vitro system.

Chapter 27 – Agricultural Chemical Percutaneous Absorption and Decontamination

Publisher Summary This chapter summarizes all the known facts about percutaneous absorption and how to efficiently protect humans from potential adverse effects of aqueous chemical exposure. Understanding percutaneous absorption as a major route of pesticides entering the body is an integral part of the risk assessment process. Percutaneous absorption is a primary focal point for dermatotoxicology and dermatopharmacology. Local and systemic toxicity depend on a chemical penetrating the skin. The skin is a barrier to absorption and a primary route to the systemic circulation. Data on humans can be obtained safely using trace measurement methodology and with low-risk doses coupled with high-tech analytical methodology. Although the data from animal and computer models are simpler to use, the method of choice is biomonitoring. Protective clothing serves to prevent agricultural workers from unnecessary pesticide exposure. A protective layer or barrier between the worker and chemical contamination prevents chemical penetration as a bulk flow through a porous material, uses nonporous material with low permeation, and absorbs or retains chemical in the fabric. Evidence suggests that often the skin and the body are unknowingly subjected to enhanced penetration and systemic absorption or toxicity because the decontamination procedure does not work or may actually enhance absorption—a phenomenon called the “wash-in.”

Hydrogen Peroxide, Blanching, and Skin: an Overview

For more than a century, hydrogen peroxide (H2O2) has been known as an antiseptic. Three percent H2O2 is used in minor wound irrigations, producing oxygen bubbles and transient skin blanching. Many people who use H2O2 as an antiseptic are alarmed at this phenomenon. This concise report provides probable mechanisms on how H2O2-induced skin blanching is produced.