Experimental irritant contact dermatitis due to cumulative epicutaneous exposure to sodium lauryl sulphate and toluene: single and concurrent application

In clinical practice, cutaneous exposure to a variety of irritants such as surfactants and solvents is frequent. Although the induction of irritant dermatitis by single irritants has been extensively studied in recent years, our knowledge of the effects of simultaneous application of different irritants is limited. Using non-invasive techniques for measurements of transepidermal water loss (TEWL) and skin colour reflectance, we quantified the irritant effects of single and concurrent application of 0.5% sodium lauryl sulphate (SLS) and undiluted toluene (TOL) in vivo. The irritants were applied twice daily for 30 min to the volar forearms of 20 volunteers. Repeated application of SLS and TOL induced an irritant reaction, as indicated by an increase in TEWL and skin redness. In contrast to SLS alone, the application of TOL alone induced only a moderate increase in TEWL, confirming previous results. Concurrent application of SLS/TOL and TOL/SLS induced significantly stronger reactions than those caused by twice daily application of each irritant on its own. Our results demonstrate that a mixed application of an anionic detergent and an organic solvent has an additive effect on skin irritation. It is suggested that pretreatment with SLS causes an increased susceptibility to TOL irritation and vice versa. Thus, the necessity for special precautions against skin absorption of TOL when handling detergents such as SLS is emphasized.     

Additive impairment of the barrier function by mechanical irritation, occlusion and sodium lauryl sulphate in vivo

BACKGROUND: The interaction between potential irritants in the workplace might be important because workers are not usually exposed to a single irritant, but to multiple potentially harmful substances. Physical irritant contact dermatitis caused by friction or mechanical abrasion is a common occupational dermatosis. Prolonged water exposure by occlusion is also common in the workplace. Several studies have revealed the negative effect of the common anionic detergent sodium lauryl sulphate (SLS) on permeability barrier function. OBJECTIVES: To study the additive impairment of permeability barrier function by mechanical irritation combined with 0.5% SLS or prolonged water exposure by occlusion, as models of mild irritation. METHODS: The volar forearms of 20 healthy volunteers were exposed to mechanical irritation and occlusion with water or 0.5% SLS for four consecutive days in a combined tandem repeated irritation test (TRIT). Permeability barrier function was measured with a Tewameter TM 210. Irritation was assessed with a Chromameter CR 300 and a visual score. RESULTS: Barrier disruption in our model was rated as follows: occlusion with SLS and mechanical irritation > occlusion with SLS > occlusion with water and mechanical irritation > mechanical irritation and occlusion with water > occlusion with a glove and mechanical irritation > mechanical irritation > occlusion with water. Barrier disruption caused by occlusion or mechanical irritation was enhanced by the tandem application. The choice of irritant under occlusion, time of occlusion and order of tandem application all affected the degree of barrier disruption. Evaporimetry was able to detect early stages in the development of an irritant reaction before it became visible. Chromametry was not able to detect this early response. CONCLUSIONS: Physical irritants (friction, abrasive grains, occlusion) and detergents such as SLS represent a significant irritation risk and should be minimized, especially when acting together, as shown in our TRIT model.     

Air flow at different temperatures increases sodium lauryl sulphate-induced barrier disruption and irritation in vivo

BACKGROUND: Combined exposure to dry climatic conditions and local heat sources together with detergents represents a common workplace situation. These conditions may support the induction of chronic barrier disruption leading subsequently to irritant contact dermatitis (ICD). OBJECTIVES: To test the irritant and barrier disrupting properties of air flow at different temperatures and velocities. METHODS: Using noninvasive biophysical measurements such as transepidermal water loss (TEWL) (TM 210; Courage & Khazaka, Cologne, Germany) we assessed the effects of short-term exposure to air flow at different temperatures (24 degrees C and 43 degrees C) in combination with sodium lauryl sulphate (SLS) 0.5% on the skin of 20 healthy volunteers in a tandem repeated irritation test. Chromametry was used to control the accuracy of the SLS irritation model. RESULTS: In our study air flow alone did not lead to a significant increase in TEWL values. Sequential treatment with air flow and SLS led to an impairment of barrier function and irritation stronger than that produced by SLS alone. The two different air flow temperatures led to different skin temperatures but had no influence on permeability barrier function. CONCLUSIONS: Warm air flow has an additional effect on the SLS-induced barrier disruption in a tandem irritation test with sequential exposure to SLS/air flow. This combination is suspected to promote ICD in workplace and household situations, especially in short-term applications as tested in our model.     

How irritant is alcohol?

BACKGROUND: Alcohol-based hand rubs are used worldwide to prevent transmission of nosocomial pathogens. OBJECTIVES: To investigate skin irritation caused by alcohols alone and in combination with detergent washing. METHODS: Single and repetitive patch testing with 60-100% alcohols [ethanol, 1-propanol, 2-propanol (synonyms: isopropyl alcohol, isopropanol)], a positive control [0.5% sodium lauryl sulphate (SLS)] and negative controls (empty chamber and water) were performed. Wash tests were performed with 80% ethanol and 0.5% SLS on the forearms with each agent alone and with both agents in a tandem design. Skin hydration, erythema and barrier disruption [measured as transepidermal water loss (TEWL)] were evaluated (always 15 volunteers). RESULTS: We found no significant change in skin barrier or erythema induced by the alcohols in the patch tests, whereas skin hydration decreased significantly. Application of alcohols to previously irritated skin did not show a stronger skin barrier disruption than application of SLS alone. Wash tests demonstrated that alcohol application caused significantly less skin irritation than washing with a detergent (TEWL, P < 0.001; skin hydration, P < 0.05; erythema, P < 0.05). Even on previously irritated skin, ethanol did not enhance irritation. By contrast, a protective effect of ethanol used after skin washing was observed (TEWL, P < 0.05; skin hydration, P < 0.05; erythema, P < 0.05). CONCLUSIONS: Alcohol-based hand rubs cause less skin irritation than hand washing and are therefore preferred for hand hygiene from the dermatological point of view. An alcohol-based hand rub may even decrease rather than increase skin irritation after a hand wash due to a mechanical partial elimination of the detergent.     

On the course of the irritant reaction after irritation with sodium lauryl sulphate

Background: The sodium lauryl sulphate (SLS) irritation test is a well-established model for irritant contact dermatitis after the effects of surfactants.
Aim of the study: The course of changes in corneometric measurements (stratum corneum hydration), in transepidermal water loss (TEWL), in laser Doppler measurements (epidermal perfusion) and in colorimetric measurements (skin redness), after a single SLS irritation, should be studied over time.
Methods: Twenty healthy volunteers were studied. Irritation with 1% SLS solution was applied to the side of one forearm for 24 h under occlusive conditions, while the symmetrical experimental site remained untreated. Measurements were made for 9 days after completion of SLS irritation.
Results: Stratum corneum hydration was reduced immediately after irritation, and subsequently a hyper-hydration was observed. The increase in TEWL, laser Doppler measurements and skin redness persisted for 7–9 days. With regard to skin redness, a mild blanching effect was noticeable after 9 days.
Discussion: The evidence of very short-term exsiccation of the stratum corneum with persistent barrier damage, as well as reactive hyper-hydration and blanching of the skin, is remarkable. These first findings suggest that exsiccation of the stratum corneum is not caused by a damage to barrier lipids.     

Effects of glycerol on human skin damaged by acute sodium lauryl sulphate treatment

Glycerol, widely used as humectant, is known to protect against irritants and to accelerate recovery of irritated skin. However, most studies were done with topical formulations (i.e. emulsions) containing glycerol in relatively high amounts, preventing drawing conclusions from direct effects. In this study, acute chemical irritations were performed on the forearm with application of a 10% sodium lauryl sulphate (SLS) aqueous solution under occlusion for 3 h. Then, glycerol aqueous solutions from 1 to 10% were applied under occlusion for 3 h. After elimination of moist excess consecutive to occlusive condition, in ambient air for 15 and 30 min, skin barrier function was investigated by dual measurement of skin hydration and transepidermal water loss (TEWL). Treatments with SLS solution under occlusion significantly increased TEWL and decreased skin hydration as assessed by capacitance measurements. The SLS irritant property was raised by the occlusion and the water barrier function as well as water content appeared impaired. Recovery with glycerol at low doses was remarkable through a mechanism that implies its hygroscopic properties and which is saturable. This precocious effect acts through skin rehydration by enhancing water-holding capacity of stratum corneum that would facilitate the late physiological repair of impaired skin barrier. Thus, glycerol appears to substitute for natural moisturizing factors that have been washed out by the detergent action of SLS, enhancing skin hydration but without restoring skin barrier function as depicted by TEWL values that remained high. Thus, irritant contact dermatitis treated with glycerol application compensate for skin dehydration, favouring physiological process to restore water barrier function of the impaired skin. Empirical use of glycerol added topical formulations onto detergent altered skin was substantiated in the present physicochemical approach.     

Less skin irritation from alcohol-based disinfectant than from detergent used for hand disinfection

BACKGROUND: The benefit of alcohol-based disinfectant used on normal skin has been debated. OBJECTIVES: The objective of the present study was to compare the effects of repeated exposure to an alcohol-based disinfectant, a detergent and an alcohol-based disinfectant/detergent alternately for 10 days, including noninvasive measurements in the evaluation. Skin reactivity in irritated skin after a 4-week interval was also evaluated. MATERIALS AND METHODS: Detergent, disinfectant and alternate disinfectant and detergent were applied twice daily every 10 min for 1 h to the ventral upper arms and forearms of 17 healthy volunteers. A control area was included. After 4 weeks an SLS patch was applied to each area. Irritant reactions were quantified with a visual score recording and measurements of transepidermal water loss (TEWL) and skin colour were performed on days 1, 5, 11, 38 and 40. RESULTS: On day 5 the detergent caused a higher visual score than either disinfectant applied alone or alternate disinfectant and detergent, P < 0.05. On day 11 detergent and alternate disinfectant and detergent caused a higher score than disinfectant, P < 0.05. An increased irritant response for detergent compared with disinfectant alone and alternate disinfectant and detergent was confirmed by TEWL evaluations on days 5 and 11, P < 0.001, while no significant difference was found by colour measurement. After 4 weeks, when evaluated by colour measurement, significantly less response to the SLS patch was found on the disinfectant-treated area compared with the control area and detergent area, and a similar trend was found for TEWL, although it was not statistically significant. CONCLUSION: Alcohol-based disinfectant caused less visible skin irritation and less skin barrier disruption than the use of detergent. The alternate use of detergent and disinfectant caused less irritation than the use of detergent, and a possible interaction between the two irritants was not indicated. After 4 weeks there was a tendency for decreased skin reactivity in the skin areas which had 4 weeks previously been exposed to disinfectant.     

Effect of an antioxidant (quercetin) on sodium-lauryl-sulfate-induced skin irritation

Quercetin is a bioflavonoid with antioxidant and anti-inflammatory activity. The purpose of this study was to examine the effect of quercetin on acute skin irritation, with special interest in the skin barrier function recovery. Acute irritant contact dermatitis was induced in 15 patients by 24-h occlusion of 2% sodium lauryl sulfate (SLS) (day (D) 1). The influence of application on SLS-irritated skin of topical quercetin for 5 consecutive Ds, compared to vehicle and controls, was studied. Parameters measured were transepidermal water loss (TEWL) and erythema index. Final measurements were taken on D 7 after a 1-D rest period. TEWL and the erythema index continued to rise 2 D after application of SLS and 1 D after treatment with quercetin, vehicle or controls. Both TEWL and erythema values at D 7 did not return to values before the SLS barrier disruption at all the test sites. Therefore, quercetin topically applied after induction of irritant contact dermatitis does not appear to increase the recovery of barrier function and erythema caused by SLS.     

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.     

Fruit acids do not enhance sodium lauryl sulphate-induced cumulative irritant contact dermatitis in vivo

Combined exposure to different irritants in the workplace may lead to irritant contact dermatitis, which is the main type of occupational dermatitis among bakers and confectioners. Following previous work on "tandem irritation", a panel of healthy volunteers was exposed twice daily for 4 days to the organic fruit acids: citric, malic, and lactic acid, either alone or in tandem application with 0.5% sodium lauryl sulphate (SLS) in a repetitive irritation test. Irritant cutaneous reactions were quantified by visual scoring and non-invasive measurement of transepidermal water loss and skin colour reflectance. Twice daily application of either citric or malic acid alone did not induce a significant irritant reaction. Combined exposure to one of the fruit acids and SLS caused marked barrier disturbance, but the latter irritant effect was smaller than that obtained by combined exposure to SLS and water. Thus, combined exposure to the above-mentioned fruit acids and SLS did not enhance cumulative skin irritation.     

SLS-irritated human skin shows no correlation between degree of proliferation and TEWL increase

Abstract It is well known that cutaneous irritants influence epidermal proliferation but the pathogenesis is poorly understood. Recent investigations have shown that the skin barrier integrity influences the proliferation of the basal keratinocytes. Our question was whether the proliferating activity of keratinocytes is indeed regulated by the degree of skin barrier damage or by a direct toxic action of the irritant on the keratinocytes. Therefore various degrees of skin irritation were induced by the application of 0.1%, 0.5% and 2% sodium lauryl sulphate (SLS) solution to the forearm skin of six healthy volunteers. This experiment was performed to evaluate the relationship between SLS concentration and epidermal proliferation. In a second experiment another 14 volunteers were treated with a single SLS concentration (0.5%) to look for interindividual differences in the patterns of skin reaction and susceptibility to the irritant. Skin barrier function was evaluated by measurements of transepidermal water loss (TEWL) before and after irritation. Punch biopsies were taken after 96 h from exposed areas and from unexposed normal skin. Dividing keratinocytes were identified immunocytochemically using three different monoclonal antibodies: PCNA, MIB 1 and KiS1. Exposure to SLS resulted in concentration-dependent increases in both TEWL and epidermal proliferation. However, no significant correlation could be found between the degree of hyperproliferation and the TEWL changes. The results suggest that epidermal proliferation is modulated by a direct interaction of the surfactant with the keratinocytes and/or by release of mediators rather than the consequence of a barrier disturbance. Received: 5 February 1997 / Received after revision: 12 August 1998 / Accepted: 24 August 1998     

Differential irritant skin responses to tandem application of topical retinoic acid and sodium lauryl sulphate: II. Effect of time between first and second exposure

In clinical practice, the cutaneous exposure to chemical irritants such as surfactants and topical drugs is frequent. Topical all-trans retinoic acid (RA) is often associated with irritation and induces epidermal changes similar to those produced by sodium lauryl sulphate (SLS). Using bioengineering techniques, e.g. assessing transepidermal water loss (TEWL), capacitance and chromametry, we investigated the variations of the skin response to SLS and RA and to both chemicals applied sequentially, allowing different time periods (from 1 h to 2 weeks) between applications of SLS and RA. Both chemicals caused irritation as assessed by visual scoring, but the values from the objective variables differed at different time periods. TEWL increased dramatically shortly after applying SLS but the increase was delayed after RA. After applying SLS, the capacitance generally decreased then returned to basal values; treatment with RA produced an overall increase. Only the results from chromametry were similar. After tandem application, the drugs were synergistic for all variables except capacitance, showing an antagonistic interaction for skin hydration. These results suggest that non-specific skin irritation profoundly reflects different mechanisms of action at tissue level. With sequential application, SLS injury modified the response to RA for at least 1 week after applying SLS. These late effects of detergents should be considered when studying irritant chemical interactions and in developing strategies for the management of occupational and other irritant dermatitis.     

Efficacy of skin barrier creams

2 barrier creams (BC) were evaluated against the anionic detergent sodium lauryl sulphate (SLS) using a new human test model. In the repetitive irritation test (RIT) on human skin, the irritant SLS is applied to the ventral forearm of Healthy volunteers daily for 2 weeks. 1%, 5%, and 10% SLS is exposed to the skin for 30 min. using a glass cup 2.5 cm in diameter. The BC is applied 30 min before the irritant. Cutaneous irritation is assessed on a score for erythema (0 to 5+), and quantified by various biophysical techniques: transepidermal water loss (TEWL) by evaporimetry, skin blood flow volume (BFV) by laser-Doppler velocimetry, and -skill colour bi colorimetry (La^* value). 10 subjects were tested with SLS on one forearm without pretreatment (control) and with Taktosan Salbe as BC on the other forearm. A 2nd panel of 10 subjects was tested in the same way with SLS and Marly skin as BC. Taktosan Salbe was extremely effective in reducing the irritation by SLS: there were significant differences regarding all lest parameters for 10% SLS in the 2nd week. The most differentiating parameter was TEWL, revealing statistical differences as early as the 1st week for 10%. SLS and Taktosan Salbe, while the least differentiating sensitivity was found for La^*. In contrast, there was no significant suppression of irritancy in any parameter with Marly skin, either in the 1st week or in the 2nd week with any concentration of SLS. The results show the differentiating potential of the model developed. Results obtained with the previously described animal model are confirmed- Noninvasive biophysical techniques, particularly TEWL measurements, might be extremely valuable in identifying new active ingredients of BC.     

Nonanoic acid--an experimental irritant

Irritant contact dermatitis is defined as a non-immunological skin reaction following exposure to various chemical, mechanical and physical factors. It is known that the skin response to irritants depends on the irritant applied and differs between chemically different irritants. Sodium lauryl sulfate (SLS) is an anionic detergent and the most frequently used substance in experimental irritant contact dermatitis. In 1980, it was suggested that nonanoic acid (NNA) could be used as a positive control when patch testing. Since then, NNA has been used as an experimental irritant in several studies and has been used as a chemically different substance compared to SLS. The present article presents a review of the application of NNA in studies on skin irritancy and experimental irritant contact dermatitis.     

Barrier function of the skin in a repetitive irritation model and influence of 2 different treatments*

Background/aims: The aim of this study was to develop and characterize an experimental model of cumulative irritant contact dermatitis using the repetitive application over 2 weeks of 2 different irritative stimuli, sodium lauryl sulphate (SLS) in low concentration and toluene. Further, it was intended to look at the effect of 2 different treatments which could influence the regeneration of the skin barrier, as already investigated in preliminary short-term experiments. Methods: Occlusive short-time daily application of the irritants (SLS 30 min; toluene 10 min) was performed. After removal of the occlusive patch, the irritated areas were treated with 2 different preparations, Lotio Alba Aquosa and vaseline (white petroleum jelly). Bioengineering techniques were used to precisely measure the skin condition. Results: A mild irritation was obtained under these experimental conditions. The bioengineering measurements allowed us to differentiate both irritants through their different influences on trans-epidermal water loss and skin hydration. Treatment with vaseline did not significantly influence the course of the irritation, but Lotio Alba Aquosa clearly potentiated it, whereby different effects were noticed for both irritative stimuli. Conclusions: The use of bioengineering techniques in this model of mild cumulative irritation allowed us to differentiate the action of both irritants, showing that they act through different mechanisms. The results of the treatments pointed out the need to treat an irritation with the right product for the right time period.     

Efficacy of 4 commercially available protective creams in the repetitive irritation test (RIT)

Protective creams (PCs) play their part in the prevention of occupational contact dermatitis, even though efficacy data are frequently lacking. 4 different commercially-available PCs were evaluated against a set of 4 standard irritants (10%, sodium lauryl sulfate (SLS) 1% sodium hydroxide (NaOH), 30% lactic acid (LA) and undiluted toluene (TOL) in the repetitive irritation test (RIT) in humans described by Frosch and Kurte. 20 subjects were tested on the paravertebral skin on the mid-back. Irritation was assessed by visual scoring, transepidermal water loss (TEWL) as an indicator of epidermal barrier function, and colorimetry as a parameter of inflammation. Very different protective effects of the PCs on irritation by chemical substances were detectable. All products were very effective against SLS irritation. No PC provided significant protection against toluene. 3 products showed a partially protective effect against all ionic irritants, while the 4ih showed less protection against SLS and NaOH, and even amplification of inflammation by TOL. Considering the range of PC effects from good protection 10 increased irritation, depending on the irritant, the need for careful selection of PCs for specific workplaces is stressed.     

Irritants in combination with a synergistic or additive effect on the skin response: an overview of tandem irritation studies

Sodium lauryl sulfate (SLS) has often been chosen as a model for irritant contact dermatitis (ICD) to study the effect of irritants in combination (1-14). Recently 'tandem', or sequential, exposures with SLS have been performed to study the mechanism of skin barrier impairment in ICD (1-6, 15). The assessment of reactions have been documented with visual scoring, transepidermal water loss (TEWL), skin colour reflectance measurements, skin blood flow; among which TEWL has been noted as the most sensitive value (16). The matched control groups were treated with either a single exposure to a single irritant or in tandem with the same irritant repeatedly. Synergistic and additive effects have been reported for various tandem pairs of irritants, however, the mechanism for both remains unclear. The results of tandem irritation studies were evaluated to define and investigate the responses produced and deduce a possible mechanism of action. Clinical ramifications, albeit complex, are discussed.     

Study of cumulative irritant contact dermatitis in man utilizing open application on subclinically irritated skin

We evaluated the effect of subclinical irritation on the cutaneous reaction elicited by cumulative short-term (30-min) application of sodium lauryl sulphate (SLS), by measuring transepidermal water loss (TEWL) and assigning visual scores. 11 healthy adult volunteers, free of skin disease and with no history of atopic dermatitis, were treated with SLS solution (1%, 2%, 5%, 7.5%). On a Monday, we applied 80 μl of 1% SLS solution and deionized water (control), using large aluminum chambers with filter paper discs, for 30 min. We measured TEWL values 2x before and after patch application of control and 1% SLS solution, and then applied 80 μl of SLS solution (2%. 5%. 7.5%) using filter paper discs. From Tuesday to Friday, we applied 80 μl of each solution, using filter paper discs, and measured TEWL before and after open application of test solutions. Compared with each corresponding group, TEWL values of SLS patch groups (S-2.0, S-5.0, S-7.5) were higher than, those of water patch groups (W-2.0, W-5.0, W-7.5), respectively. TEWL values of each groups increased stepwise and the final (hour 97) TEWL values were higher than those of baseline (hour 0) TEWL. The mean visual scores of the vehicle control were lower than those of other test groups, but there were no statistically significant differences in visual scores between each test group. These findings suggested that impaired skin barrier function, elicited by subclinical irritation from short-duration contact with some irritants, might augment the cumulative irritant contact dermatitis caused by repeated open exposure to other surfactants. Relatively short-term and minimal exposure, not in great excess of many daily surfactant exposures, produced cumulative irritation. TEWL measurements were more discriminating than visual grading.     

Variation in barrier impairment and inflammation of human skin as determined by sodium lauryl sulphate penetration rate

BACKGROUND: Skin irritability after a brief exposure to the model skin irritant, sodium lauryl sulphate (SLS), is known to vary considerably between individuals. A difference in the skin barrier to SLS may contribute to this variation. To date, no human in vivo data have been available on SLS penetration into the skin. OBJECTIVES: We studied whether the SLS penetration rate into the stratum corneum (SC) is related to impairment of the water barrier function and inflammation of the skin. METHODS: The penetration of SLS into the SC was assessed using a noninvasive tape-stripping procedure in 20 volunteers after a 4-h exposure to 1% SLS. Additionally, the effect of a 24-h exposure to 1% SLS on the skin water barrier function was assessed by measuring the transepidermal water loss (TEWL). The accompanying inflammation was quantified by measuring erythema. RESULTS: The mean +/- SD diffusivity of SLS (D) and the SLS permeability coefficient (Kp) were 1.4 +/- 0.6 x 10(-8) cm2 h(-1) and 1.5 +/- 0.7 x 10(-3) cm h(-1), respectively. A multiple regression analysis showed that the baseline TEWL, SC thickness and SLS penetration parameters K (SC/water partition coefficient) and D clearly influenced the increase in TEWL after the 24-h irritation test (explained variance: r2 = 0.80). Change in erythema was mainly influenced by SC thickness. CONCLUSIONS: We found that variation in the barrier impairment and inflammation of human skin depends on the SLS penetration rate, which was mainly determined by SC thickness.     

Impact of glove occlusion on cumulative skin irritation with or without hand cleanser–comparison in an experimental repeated irritation model

Background. Irritant contact dermatitis remains a substantial problem in the food processing industries. Irritants that are weak by themselves, such as glove occlusion and mild detergents, could interact to produce contact dermatitis. Objectives. To model the irritant action of an antibacterial hand cleanser and glove occlusion, with sodium lauryl sulfate (SLS) as a positive control. The effects of a pre‐exposure cream and a post‐exposure cream were also investigated. Methods. A modified repeated short‐time occlusive irritation test with 20 healthy volunteers, and application of irritants over 4 days, with pre‐exposure and post‐exposure creams and overnight glove occlusion, was performed. The changes in transepidermal water loss (TEWL) served as a measure of the irritant damage to the epidermal barrier. Results. The antibacterial cleanser and the glove occlusion separately induced only minor increases in TEWL. When combined, the two showed a tandem effect, as the TEWL increase was significantly higher, and was similar to that seen with the positive control, SLS. The pre‐exposure and post‐exposure creams alone significantly mitigated the cumulative irritation, and this effect was strongest when the two creams were combined. Conclusions. Irritant contact dermatitis may develop through the tandem effects of long‐term glove occlusion and the accumulation of barrier damage from hand washing, even when mild hand cleansers are employed.