Susceptibility to irritant dermatitis induced by sodium lauryl sulfate

Skin barrier response to active chlorine hand disinfectant-An experimental study comparing skin barrier response to active chlorine hand disinfectant and alcohol-based hand rub on healthy skin and eczematous skin

BACKGROUND

Alcohol-based hand rub (ABHR) is widely used for hand disinfection in the health care sector. ABHR is, however, known to cause discomfort when applied on damaged skin emphasizing the unmet need for alternative and better tolerated types of disinfectants. Active chlorine hand disinfectants (ACHDs) are potential new candidates; however, the effect on the skin barrier function compared to ABHR remains to be assessed.

MATERIALS AND METHODS

In Study A, the forearm skin of healthy adults was repeatedly exposed to ACHD and ABHR. Skin barrier function was assessed by measurement of transepidermal water loss, electrical conductance, pH, and erythema at baseline and at follow-up after 2 days, and subjective discomfort was likewise assessed. Study B was performed in the same way; however, in order to induce an experimental irritant contact dermatitis, sodium lauryl sulfate patch tests were applied to forearms before exposure to ACHD and ABHR.

RESULTS

In both studies, the skin barrier function was unaffected after repetitive exposure to ACHD and ABHR, and with no significant differences between the products. Subjective discomfort was reported as sporadic or very mild in relation to both products.

CONCLUSION

Our results illustrate that use of ACHD does not affect the skin barrier function negatively, neither in intact skin nor in skin with experimentally induced contact dermatitis. Future studies should include real-life evaluation of skin barrier function and subjective discomfort following ACHD use in individuals with and without hand eczema.

The Importance of Acidification in Atopic Eczema: An Underexplored Avenue for Treatment

Atopic dermatitis is a form of dermatitis commonly seen in children and adults. Its pathophysiology is complex and is centered on the barrier function of the epidermis. An important aspect of the skin’s barrier is pH, which in turn affects a number of parameters such as the skin flora, protease function, and mediators of inflammation and pruritus. Normal pH for non-neonatal skin is acidic and ranges from 4 to 6. Skin pH in atopic dermatitis patients is often increased into the neutral to basic range, and the resulting cascade of changes contributes to the phenotype of atopic dermatitis. Therefore, the maintenance of normal skin pH remains an important topic in understanding and treating atopic dermatitis. This article will review skin pH and its impact on normal barrier function, pathological pH changes in atopic dermatitis, and the therapeutic considerations related to restoring and maintaining pH balance.

Natural skin surface pH is on average below 5, which is beneficial for its resident flora

Variable skin pH values are being reported in literature, all in the acidic range but with a broad range from pH 4.0 to 7.0. In a multicentre study (N = 330), we have assessed the skin surface pH of the volar forearm before and after refraining from showering and cosmetic product application for 24 h. The average pH dropped from 5.12 +/- 0.56 to 4.93 +/- 0.45. On the basis of this pH drop, it is estimated that the 'natural' skin surface pH is on average 4.7, i.e. below 5. This is in line with existing literature, where a relatively large number of reports (c. 50%) actually describes pH values below 5.0; this is in contrast to the general assumption, that skin surface pH is on average between 5.0 and 6.0. Not only prior use of cosmetic products, especially soaps, have profound influence on skin surface pH, but the use of plain tap water, in Europe with a pH value generally around 8.0, will increase skin pH up to 6 h after application before returning to its 'natural' value of on average below 5.0. It is demonstrated that skin with pH values below 5.0 is in a better condition than skin with pH values above 5.0, as shown by measuring the biophysical parameters of barrier function, moisturization and scaling. The effect of pH on adhesion of resident skin microflora was also assessed; an acid skin pH (4-4.5) keeps the resident bacterial flora attached to the skin, whereas an alkaline pH (8-9) promotes the dispersal from the skin.

Chemical Burn Induced by Cutaneous Exposure to a Concentrated Sodium Hypochlorite and Alkyl Sulfate Solution

BACKGROUND

Acute irritant contact dermatitis induced by cutaneous exposure to chemicals is a common dermatologic problem in the workplace. In severe cases, irritant contact responses can result in a caustic burn. Chemical burn induced by concentrated sodium hypochlorite (the active ingredient in bleach) has been reported infrequently in the literature, with no previously reported cases of chemical burn due to an alkyl sulfate (a common surfactant in cleaning fluids). Here we describe a chemical burn in a 16-year-old girl resulting from exposure to a solution of concentrated sodium hypochlorite and alkyl sulfate applied as a sanitizer to the interior of roller skates worn at work.

OBSERVATIONS

The diagnosis was made on the basis of the patient's exposure history, clinical appearance, and laboratory results. On physical examination, the erythematous plaque, located at the site of chemical exposure, had intact skin lines, surrounding edema, and decreased sensitivity to touch. The peripheral white blood cell count was within normal limits and bacterial and fungal cultures from the lesion were negative.

CONCLUSIONS

The irritant effect of exposure to chemicals, including those that usually are not major irritants, and the possible additive effect of simultaneous exposure to different chemicals, should be considered in the differential diagnosis of acute dermatitis of unknown etiology. Moreover, increased reporting of cases of chemical-induced acute irritant contact dermatitis will help lead to crucial early and appropriate treatment.

The pH of the Skin Surface and Its Impact on the Barrier Function

The 'acid mantle' of the stratum corneum seems to be important for both permeability barrier formation and cutaneous antimicrobial defense. However, the origin of the acidic pH, measurable on the skin surface, remains conjectural. Passive and active influencing factors have been proposed, e.g. eccrine and sebaceous secretions as well as proton pumps. In recent years, numerous investigations have been published focusing on the changes in the pH of the deeper layers of the stratum corneum, as well as on the influence of physiological and pathological factors. The pH of the skin follows a sharp gradient across the stratum corneum, which is suspected to be important in controlling enzymatic activities and skin renewal. The skin pH is affected by a great number of endogenous factors, e.g. skin moisture, sweat, sebum, anatomic site, genetic predisposition and age. In addition, exogenous factors like detergents, application of cosmetic products, occlusive dressings as well as topical antibiotics may influence the skin pH. Changes in the pH are reported to play a role in the pathogenesis of skin diseases like irritant contact dermatitis, atopic dermatitis, ichthyosis, acne vulgaris and Candida albicans infections. Therefore, the use of skin cleansing agents, especially synthetic detergents with a pH of about 5.5, may be of relevance in the prevention and treatment of those skin diseases.

A randomized, controlled, double-blind study of the effect of wearing coated pH 5.5 latex gloves compared with standard powder-free latex gloves on skin pH, transepidermal water loss and skin irritation

Hand dermatitis is a common occupational disease. Altered skin pH plays an important role in the development of skin irritation. A glove that maintains tight control over skin pH may reduce hand dermatitis in glove users. The purpose of the study was to characterize the effect of glove wearing on skin pH, investigate the impact of study glove on skin pH compared with standard gloves and determine whether wearing study gloves reduced irritation. 20 healthy volunteers enrolled in a 4-week double-blind comparison of study and control gloves and served as their own controls. Gloves were worn 8 hr per day for 5 days per week. Skin pH and transepidermal water loss were measured during and 2 days after the glove-wearing period. The subject and an observer assessed the skin for irritation. The study glove maintained lower skin pH than the control glove (P < 0.05) and trended towards having less irritation. Observers noted increases in dryness and scale in both hands after 4 weeks but significantly less dryness in the study hand at week 4 (P = 0.006). Glove wearing increased skin pH and dryness. The pH 5.5 glove maintained lower skin pH levels than the control glove and may reduce irritation in long-term glove wearers.

Sodium lauryl sulfate-induced irritation in the human face: regional and age-related differences

The particular sensitivity of the human face to care products prompted us to study irritation induced by sodium lauryl sulfate (SLS) in its various regions. We examined regional and age-related differences, correlating basal transepidermal water loss (TEWL) and capacitance to SLS irritation. SLS (2% aq.) was applied under occlusion for 1 h to the forehead, cheek, nose, nasolabial and perioral areas, chin, neck and forearm to two groups of subjects--one with 10 subjects with an average age of 25.2 +/- 4.7 years and another with 10 subjects with an average age of 73.7 +/- 3.9 years. TEWL was measured before and 1 h and 23 h after patch removal. Baseline stratum corneum hydration was also measured. Irritation was assessed by the changes in TEWL (deltaTEWL = TEWL after patch removal - basal TEWL) after corrections to the control. In the younger group, all areas of the face and the neck reacted to SLS, whereas the forearm did not. In the older group, the nose, perioral area and forearm did not react. In both age groups, some significant differences between the regions of the face were detected. The younger group showed higher changes in TEWL than the older group in all the areas studied, but only in the chin and nasolabial area were the differences statistically significant. Significant correlations were found between basal TEWL and deltaTEWL in 5 of the 7 areas which reacted to SLS. Baseline TEWL is one parameter that correlates with the susceptibility of the face to this irritant.

Long-term repetitive sodium lauryl sulfate-induced irritation of the skin: an in vivo study

Skin may adapt to topical irritants through accommodation. This study focuses on long-term exposure to irritants and attempts to demonstrate accommodation. Sodium lauryl sulfate (SLS) induced irritant contact dermatitis at 3 concentrations (0.025% to 0.075%). Distilled water, acetone and an empty chamber served as controls. Experimental compounds were applied to forearms of 7 healthy volunteers for 24 hr before replacing by a fresh chamber for 6 non-consecutive weeks over 103 days. Possible accommodation was quantified by visual scoring (erythema and dryness) and by bioengineering parameters: transepidermal water loss (TEWL), capacitance, chromametry and laser Doppler flowmetry (LDF). Significant erythema, dryness, elevated TEWL, skin colour reflectance and LDF values occurred during the exposure periods. Upon repeat exposure, an immediate and augmented response in erythema, TEWL, skin colour reflectance and LDF developed. However, irritant skin changes were not sustained. Irritation parameters return to baseline after cessation of exposure. There was no evidence of sustained irritation or accommodation after the last exposure. Study findings do not document sustained accommodation or adaptive hyposensitivity after long-term repetitive irritant exposure under these test conditions. Alternative models should be developed to prove or disprove the accommodation hypothesis.

Effects of skin occlusion in patch testing with sodium lauryl sulphate

BACKGROUND

When evaluating transepidermal water loss (TEWL) in patch testing, the occlusive effect of the patch must be considered as an important artificial impairment of the measurement.

OBJECTIVES

To investigate the time course of effects of occlusion.

METHODS

Epicutaneous patches with sodium lauryl sulphate (SLS) 0.25%, SLS 0.5%, water and an empty test chamber (control) were applied on the volar forearm for different time intervals (12, 24, 48 h). Test reactions were evaluated by measurement of TEWL immediately, every 15 min during the first hour, every 30 min during the following 3 h and 24 h after patch removal.

RESULTS

After patch removal, TEWL values showed a steep increase. When compared with basal values, TEWL values after SLS patch testing remained increased for 24 h, whereas TEWL values on water patch sites were only significantly increased for up to 180 min, and on empty patch sites for only up to 120 min after patch removal. The prolonged increase in TEWL values in SLS patch testing seemed to be induced by barrier function damage caused by SLS itself, as shown in various earlier studies. After the initial increase, TEWL values showed a significant decrease for all patches from 0 to 120 min after patch removal. Patch testing with water gave a significant decrease in TEWL values up to 180 min, and for empty chambers (control) up to 150 min after removal of patches. These data suggest that the occlusive effect on TEWL in patch testing ends 3 h after the removal of test chambers.

CONCLUSIONS

We recommend TEWL measurement in SLS patch testing after a period of at least 3 h after patch removal. For practical purposes a 24-h period after patch removal may be useful.

The acidic milieu of the horny layer: new findings on the physiology and pathophysiology of skin pH

The acidic pH of the horny layer, measurable on the skin surface, has long been regarded as a result of exocrine secretion of the skin glands. The 'acid mantle' was thought to regulate the bacterial skin flora and to be sensitive primarily to skin cleansing procedures. In recent years, an increasing number of investigations have been published on the changes in, and constituents and functions of, the pH of the deeper layers of the stratum corneum, as well as on the influence of physiological and pathological factors. A central role for the acidic milieu as a regulating factor in stratum corneum homeostasis is now emerging. This has relevance to the integrity of the barrier function, from normal maturation of the stratum corneum lipids through to desquamation. Changes in the pH and the organic factors influencing it appear to play a role, not only in the pathogenesis, prevention and treatment of irritant contact dermatitis, but also of atopic dermatitis and ichthyosis and in wound healing. On the basis of these findings, a broader concept, exceeding the superficial 'acid mantle' theory, has been formulated.

Guidelines on sodium lauryl sulfate (SLS) exposure tests. A report from the Standardization Group of the European Society of Contact Dermatitis

This report reviews the clinical and histopathological reactions caused by sodium lauryl sulfate (SLS), and the non-invasive methods that can characterize these reactions. Furthermore, SLS exposure techniques and factors that may influence the outcome of these exposures are discussed. Finally, guidelines are introduced for each exposure technique in order to have a uniform approach to SLS testing in man. Since different study aims warrant different testing conditions, we have proposed 2 categories, namely susceptibility testing and provocative testing, tailored to the aim with which the study is performed.

Skin reactivity to sodium lauryl sulfate in patients with respiratory atopy

BACKGROUND

No literature data are available on the skin reactivity of patients with respiratory atopy alone.

OBJECTIVE

Our purpose was to assess skin reactivity to detergents in patients with allergic asthma, rhinitis, or both.

METHODS

The skin of the volar aspect of the forearm of 19 subjects with allergic asthma or rhinitis (or both) was challenged with a single exposure to 0.5% sodium lauryl sulfate. The skin response was evaluated by transepidermal water loss (TEWL), capacitance, and echogenicity measurements. Results were compared with those obtained in 19 patients with atopic dermatitis (AD) and 20 healthy subjects.

RESULTS

In patients with AD preexposure TEWL values were higher than in healthy subjects, whereas capacitance values were lower. In this patient group, postexposure TEWL, capacitance, and echogenicity values showed more pronounced variations than in healthy subjects. Conversely, in patients with allergic asthma or rhinitis (or both), both baseline and postexposure TEWL, capacitance, and echogenicity values were similar to those in healthy subjects.

CONCLUSION

Patients with respiratory atopy without AD do not have the functional abnormalities characteristic of skin affected by AD, either under baseline conditions or after exposure to sodium lauryl sulfate.

Surfactant-induced dermatitis: comparison of corneosurfametry with predictive testing on human and reconstructed skin

BACKGROUND

Surfactants elicit alterations in the stratum corneum. Predictive tests that avoid animal experimentation are needed.

OBJECTIVE

This study compares three methods of rating and predicting shampoo-induced irritation.

METHODS

Corneosurfametry entails collection of stratum corneum followed by brief contact with diluted surfactants and measurement of variations in staining of samples.

RESULTS

Corneosurfametry appears to correlate well with in vivo testing in volunteers with sensitive skin. However, corneosurfametry presents less interindividual variability than in vivo testing and allows better discrimination among mild products. Morphologic information about surfactant-induced loosening of corneocytes may be increased by testing surfactants on human skin equivalent. Results are similar to those provided by specimens used for corneosurfametry.

CONCLUSION

The corneosurfametric prediction of surfactant irritancy correlates with in vivo testing and with in vitro evaluation on human skin equivalent.

The sodium lauryl sulfate model: an overview

Irritant contact dermatitis is a complex entity with several clinical forms (acute, cumulative, etc.) and multiple mechanisms. Sodium lauryl sulfate (SLS), the most widely utilized model for studying acute and cumulative irritation, has proved highly practical and informative for such studies. This article summarizes several decades of investigation, and provides details of dosing, application method (closed versus open), and biologic endpoints (visual grading, transepidermal water loss) that may be utilized in future studies.

Fate and effects of the surfactant sodium dodecyl sulfate

Sodium dodecyl sulfate is the most widely used of the anionic alkyl sulfate surfactants. Its surface-active properties make it important in hundreds of household and industrial cleaners, personal care products, and cosmetics. It is also used in several types of industrial manufacturing processes, as a delivery aid in pharmaceuticals, and in biochemical research involving electrophoresis. SDS synthesis is a relatively simple process involving the sulfation of 1-dodecanol followed by neutralization with a cation source. Purification is accomplished through repeated extraction. It is available commercially in both broad-cut and purified forms. Although its environmental occurrence arises mainly from its presence in complex domestic and industrial effluents, SDS is also directly released in some applications (e.g., oil dispersants and pesticides). Although surfactants are known to significantly contribute to the toxicity of some effluents, no official water quality standards currently exist. Research has shown SDS to be highly biodegradable by a large number of naturally occurring bacteria, and degradation is generally reported to be > or = 90% within 24 hr. The process involves initial enzymatic sulfate liberation and conversion to dodecanoic acid, followed by either beta-oxidative shortening or elongation and desaturation. All surfactant properties are lost after initial sulfate hydrolysis. SDS can enhance absorption of chemicals through skin, gastrointestinal mucosa, and other mucous membranes. Thus, it is used in transepidermal, nasal, and ocular drug delivery systems and to enhance the intestinal absorption of poorly absorbed drugs; enhancement is concentration dependent. Human exposure is mainly through oral ingestion and dermal contact, although cases of respiratory exposure are known. The main sources of daily intake are ingestion of personal care products, residues on insufficiently rinsed utensils, and contaminated drinking water. Uptake, distribution, and excretion of SDS are all rapid. In fish, uptake in various tissues plateaus within 24-72 hr, with elimination occurring within < 24-48 hr; selective accumulation occurs in the hepatopancreas and gall bladder. In mammals, it is readily absorbed via the intestine, colon, and skin. Metabolism is similar in fish and mammals, proceeding from initial omega-oxidation to a carboxylic acid, then to beta-oxidation to butyric acid 4-sulfate, which is finally nonenzymatically desulfurated to gamma-butyrolactone and inorganic sulfate. SDS elicits both physical and biochemical effects on cells, with the membrane the primary target structure. Effects are concentration dependent and range from loss of barrier function and increased permeability to complete cell lysis. Hemolysis in mammals is pH dependent.(ABSTRACT TRUNCATED AT 400 WORDS)

Skin susceptibility in uninvolved skin of hand eczema patients and healthy controls

Basic physiological characteristics were examined in the uninvolved skin of 39 patients with hand eczema and in 39 healthy controls. Susceptibility to sodium lauryl sulphate (SLS)-induced irritant dermatitis was evaluated by the application of a single 24-h SLS patch test to the upper arm. Transepidermal water loss (TEWL) was measured by an evaporimeter, skin thickness by ultrasound A-scan, blood flow by laser-Doppler flowmetry and skin colour by a chroma meter using the L*a*b* system of the Commission Internationale de l'Eclairage (CIE). No difference in basal TEWL values was found between patients and controls. A decreased skin thickness was found in those with hand eczema as compared to the controls. The hand eczema patients had significantly increased L* and decreased b*-values compared to controls, indicating a more 'fair' skin. Susceptibility to SLS was increased only in patients with acute eczema, indicating that the presence of an active eczema increases the reactivity to irritants of distant uninvolved skin.

Basal transepidermal water loss, skin thickness, skin blood flow and skin colour in relation to sodium-lauryl-sulphate-induced irritation in normal skin

The influence of basal transepidermal water loss (TEWL), skin thickness, blood flow and skin colour on susceptibility to sodium-lauryl-sulphate(SLS)-induced irritant contact dermatitis was studied in 70 healthy volunteers. SLS 0.5% was applied as a patch test. For assessment of basal values and skin response to SLS, bioengineering methods were used: TEWL was measured by an evaporimeter, skin thickness by ultrasound A-scan, blood flow by laser Doppler flowmetry, and skin colour by a colorimeter, using the L*a*b* system of the Commission Internationale de l'Eclairage (CIE). By use of multiple regression analysis, it was demonstrated that basal TEWL was substantially related to skin susceptibility to SLS, high basal TEWL predicting an increased susceptibility to SLS. Also increased light reflection from the skin, indicating a 'fair' skin, was found to be associated with increased susceptibility to SLS.