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.     

Sequential application of cold and sodium lauryl sulphate decreases irritation and barrier disruption in vivo in humans

BACKGROUND: Irritant contact dermatitis (ICD) is one of the most frequent types of occupational dermatitis. Different factors are involved in the development of contact dermatitis. In the food-processing industry, the combined exposure to different irritants may be involved in the development of ICD. Few data have been published regarding the irritant potential of sodium lauryl sulphate (SLS) in combination with cold. OBJECTIVES: The present study was intended to analyse whether cold exposure and low skin temperature influence the development of ICD. METHODS: Twenty (part I) and 12 (part II) healthy volunteers were exposed twice daily for 4 days to SLS alone, different low temperatures alone (4 degrees C six times for 90 s with an interval of 20 s or 15 degrees C for 10 min) or a combination of cold and SLS (19.6 microL SLS 1% cm(-2), part I; or 52.6 microL SLS 0.5% cm(-2), part II) using the tandem repetitive irritation test. Irritant cutaneous reactions were measured by noninvasive biophysical methods with transepidermal water loss as a parameter for permeability barrier function and skin colour reflectance together with visual scoring as parameters for inflammatory reactions. RESULTS: Cold alone caused no significant skin reaction compared with untreated control. Exposure to SLS alone and SLS together with cold (independent of the applied temperature of 4 or 15 degrees C) twice daily induced a clear irritant reaction and barrier disturbance. Reactions did not differ whether SLS was applied before or after cold. Furthermore, 'tandem application' of cold and SLS diminished the barrier disruption and irritant reaction compared with SLS alone. CONCLUSIONS: We conclude that the application of cold may have a protective effect on the development of ICD, at least in our short-term model.     

The tandem repeated irritation test: a new method to assess prevention of irritant combination damage to the skin

The effect of a protective cream was tested in a new tandem repeated irritation test with tandem application of 0.5% sodium lauryl sulphate (SLS) and undiluted toluene. The irritants were applied twice daily for 30 min to the ventral forearms of 20 volunteers. Irritant cutaneous reactions were quantified by a visual score, transepidermal water loss, chromametry and skin capacitance. Concurrent application of SLS/toluene induced stronger reactions than those caused by twice daily application of each irritant on its own. A protective effect of the protective cream was obtained against all treatment combinations and was significant for SLS/SLS (p < or = 0.01) and SLS/ toluene (p < or = 0.05). Our results indicate that the tandem repetitive irritation test has great potential in the evaluation of skin care products to prevent irritant contact dermatitis.     

Fruit acids and sodium hydroxide in the food industry and their combined effect with sodium lauryl sulphate: controlled in vivo tandem irritation study

BACKGROUND: Cutaneous exposure to a variety of irritants has been extensively studied in recent years. Nevertheless, knowledge of the induction of irritant dermatitis, especially by mild irritants at low doses and for a short duration of exposure, is still incomplete. OBJECTIVES: To quantify the irritant effects and barrier disruption properties of ascorbic acid (ASC), acetic acid (ACA) and sodium hydroxide (NaOH), particularly in combination with an anionic detergent, sodium lauryl sulphate (SLS). METHODS: In a tandem repeated irritation test, the irritants were applied for 30 min twice daily for 4 days to the skin of the mid-back of 19 healthy volunteers of both sexes. We used bioengineering techniques for measurement of transepidermal water loss (TEWL) and skin colour reflectance, as well as visual scoring. RESULTS: Repeated application of ASC and ACA caused a moderate increase in TEWL and erythema. The sequential application of ASC or ACA and SLS enhanced these effects. NaOH induced a strong reaction when applied both occlusively and nonocclusively as well as in combination with SLS, with an early onset of the inflammatory signs, leading to discontinuation of the application on the third day in most of the test fields. Notably, the irritant effect of NaOH was not as marked when applied sequentially with SLS. CONCLUSIONS: Our results demonstrate that concurrent application of an anionic detergent and a mild acidic irritant can lead to disruption of the barrier function which, although not additive, is still considerable. The combined application of SLS and mild acids does not prevent SLS-induced irritation. Furthermore, we showed that NaOH in low concentrations may also act as a potent irritant but that its effect is not enhanced by SLS. The necessity of adequate skin protection and reduction of contact with substances that are potentially barrier disruptive and irritant, e.g. in the food industry, is emphasized, not only when handling detergents, but also when processing food products.     

Post-application occlusion substantially increases the irritant response of the skin to repeated short-term sodium lauryl sulfate (SLS) exposure

Occlusion often, but not always, enhances percutaneous absorption and thus may facilitate skin irritation. Quantitative data about the impact occlusivity may have on minimal irritant stimuli to which the skin is exposed in daily life, and which may lead to chronic irritant contact dermatitis, are however lacking. Irritant stimuli were administered by repeated application of sodium lauryl sulfate (SLS) in an open application procedure. After the open exposure, the skin was either left open or occluded with plastic. Skin irritancy was assessed by means of visual grading and by transepidermal water loss (TEWL) measurements. Post-exposure occlusive treatment markedly enhanced the irritant response. 5 consecutive daily applications produced more irritation, with or without occlusion, than alternate day application. Occlusion may be a relevant factor in the development of irritant contact dermatitis from certain chemicals.     

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.     

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.     

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.     

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.     

The hairless guinea-pig as a model for treatment of cumulative irritation in humans

BACKGROUND: The effect of six skin-care formulations (SCFs) on experimentally induced cumulative irritation was studied in hairless guinea-pigs (HLGPs) and in human volunteers (HVs). The formulations were a basic cream, a carbomer cream and four modifications of the carbomer cream, containing either 10% isopropyl palmitate (IPP cream), 10% glycerol (glycerol cream), 19.5% canola oil (canola oil cream) or 0.5% (-)-alpha-bisabolol (bisabolol cream). METHODS: In HLGP, irritant dermatitis was induced with 30 min daily exposure for 4 days to 0.5% sodium lauryl sulfate aq. (SLS). In HVs, irritant dermatitis was induced with 10 min daily exposure for 5+4 days (no irritation on weekends) to 3% SLS aq. on the right and 30% nonanoic acid (NON) in n-propanol on the left volar forearm. Clinical scoring was performed daily; evaporimetry (total epidermal water loss (TEWL)), hydration and colorimetry were measured at baseline (day 0) in the middle and at the end of treatment. Treatments were applied twice daily. The basic cream and the IPP cream were excluded from testing in HLGP because they were known from previous studies to be irritant in HLGP, while all formulations were known to be equally and well tolerated locally in humans. RESULTS: All formulations worsened the skin irritation in HLGP: the glycerol cream the least, the canola oil cream the most, while the bisabolol cream and the carbomer cream were indistinguishable. In humans, the glycerol cream was better than 'No Treatment' after cumulative irritation with both SLS and NON. The basic cream was better tolerated in humans than was expected from previous testing in HLGPs. CONCLUSION: In conclusion, the results from the studies in HLGPs and HVs are in agreement with regard to ranking of the SCFs. Further, the glycerol cream showed a positive treatment effect on both SLS- and NON-irritated skin in HVs.     

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.     

Evidence of increased skin irritation after wet work: impact of water exposure and occlusion

Background. Exposure to humid environments/water and prolonged glove occlusion are both believed to cause irritant contact dermatitis. Objectives. To study the effects of different forms of wet work, especially the differences between water exposure and occlusion, by using an experimental model simulating occupational wet work. Methods. The responses to water exposure and occlusion over multiple daily exposure periods for 7 days were compared in 73 volunteers. After the 1 week exposure, the sites were irritated with sodium lauryl sulfate (SLS). Comparison was performed via visual inspection and bioengineering methods. Results. Whereas occlusion did not induce measurable alterations in skin physiology, water exposure for more than 3 hr daily caused a significant increase in transepidermal water loss (TEWL) as compared with the control areas. SLS irritation of the previously occluded and the water-exposed sites induced higher TEWL and clinical scores in a time-dependent fashion as compared with the control areas, with more pronounced reactions in the water-exposed sites than in the occluded sites. Conclusion. Both previous occlusion and water exposure were capable of inducing higher susceptibility to SLS irritation. Skin hydration by occlusion had a different biological effect than water exposure. Short occlusions seem to harm the skin less than water exposure for the same duration.     

Irritant reactivity in males and females

Repeated, daily, open sodium lauryl sulfate (SLS) applications caused slight alterations in transepidermal water loss (TEWL) and dielectric water content (DEWC) in males and females. No erythema developed. Inter-individual variation in skin reactivity was demonstrated; sex-related patterns in reactivity to open cumulative irritant exposure did not exist. In patch testing with 0.5 and 1% SLS, reflecting acute irritation capacity, the reaction pattern, assessed by TEWL, DEWC, laser Doppler velocimetry (LDV) and visual scoring (VS), differed from that induced by open, cumulative SLS irritation. Again, inter-individual variation in the reactivity was demonstrated; significant sex-related differences did not develop. Individual reactivity showed considerable variation in acute and cumulative irritant response and was greater than the sex-related variation. We did not identify responses demonstrating that women have delicate (easily irritated) skin, nor that males have "tougher" skin than females.     

Effects of disinfectants and detergents on skin irritation

We investigated the biological response of regular human skin to alcohol-based disinfectants and detergents in a repetitive test design. Using non-invasive diagnostic tools such as transepidermal water loss, laser-Doppler flowmetry and corneometry, we quantified the irritative effects of a propanol-based hand disinfectant (Sterillium), its propanol mixture (2-propanol 45% w/w and 1-propanol 30% w/w), sodium lauryl sulfate (SLS) 0.5% and distilled water. The substances were applied in a 2-D patch test in a repetitive occlusive test design to the back. Additionally, we performed a wash test on the forearms that was supposed to mimic the skin affection in the normal daily routine of health care workers. In this controlled half-side test design, we included the single application of the hand rub, SLS 0.5% and water as well as a tandem application of the same substances. Patch test and wash test showed similar results. The alcohol-based test preparations showed minimal irritation rather comparable to the application of water. However, the detergent SLS produced stronger barrier disruption, erythema and dryness than the alcohol-based preparations. There was no additional irritation at the combined use of SLS and disinfectants. By contrary, there was even a decrease in barrier disruption and erythema induced by the tandem application of SLS followed by alcohol-based disinfection compared with the use of SLS alone. These findings show a less irritant effect of alcohol-based disinfectants on the skin than detergents. Our study shows that there is no summation of irritating effects of a common detergent and propanol and that the combination of washing and disinfection has a rather protective aspect compared with washing alone.     

Urea-containing moisturizers influence barrier properties of normal skin

Moisturizers are used in the treatment of dry skin, both clinically and in cosmetic products. In the present study the influence of different moisturizers on the normal skin barrier properties was evaluated by measuring transepidermal water loss (TEWL) and skin capacitance. In addition, the skin reactivity to a topically applied surfactant, sodium lauryl sulphate (SLS), following the use of the moisturizers was examined. The skin reaction was assessed visually and by measuring TEWL and superficial blood flow. Treatment with two urea-containing moisturizers for 10 and 20 days decreased TEWL. The irritant reactions after exposure to SLS were also significantly decreased after prior treatment for 20 days with the urea-containing moisturizers. In a double-blind vehicle-controlled part of the study, urea was found to decrease the skin susceptibility to SLS after only three applications. However, this decrease in skin reactivity was not preceded by a reduction in TEWL. Skin capacitance increased after three applications of urea-containing moisturizers and was still increased after 10 days, but not after 20 days of this treatment. Treatment for 20 days with two moisturizers without urea did not influence either TEWL or the susceptibility to irritation from SLS, but it increased the skin capacitance significantly. The mechanism underlying these changes is not known. The lower degree of SLS-induced irritation in the skin treated previously with urea-containing moisturizers may be of clinical relevance in reducing contact dermatitis from irritant stimuli. Received: 5 January 1995     

Combined effects of irritants and allergens. Synergistic effects of nickel and sodium lauryl sulfate in nickel- sensitized individuals

Knowledge of the combined effects of irritants and allergens is of interest with respect to accurate risk assessment. The threshold for elicitation of allergic contact dermatitis in previously sensitized individuals may theoretically be markedly influenced by the simultaneous presence of irritants and allergens. Combined exposures have, however, only been studied infrequently. In the present study, the combined effect of an irritant and an allergen was evaluated in a dose-response designed experimental study. 20 nickel-sensitized subjects were exposed to patch testing with varying concentrations of NiCl2 (nickel chloride) and sodium lauryl sulfate (SLS) alone and in combination. Evaluation of skin reactions was performed by colorimetry, measurement of transepidermal water loss and clinical evaluation, and the data were analyzed by logistic dose-response models. A synergistic effect was found of combined exposure to NiCl2 and SLS, as compared to each of the substances applied separately, as evaluated by colorimetry and clinical scoring. This means that the effect produced by the combined exposure was substantially greater than the effect produced by either of the substances alone. A synergistic effect of combined exposure on skin barrier impairment was not found, since the barrier function is significantly influenced by SLS-exposure only and not by NiCl2. Concentration limits are used by industry and government agencies to protect consumers. The present results clearly illustrate that elicitation thresholds and concentration limits may be influenced considerably by combined exposure to allergens and irritants.     

Barrier recovery and influence of irritant stimuli in skin treated with a moisturizing cream

Moisturizers are used daily by many people to alleviate symptoms of clinically and subjectively dry skin. Recent studies suggest that certain ingredients in creams may accelerate the recovery of a disrupted barrier and decrease the skin susceptibility to irritant stimuli. In the present single-blind study, a moisturizing cream was tested for its influence both on barrier recovery in surfuctant-damaged skin and on the susceptibility of normal skin to exposure to the irritant sodium lauryl sulphate (SLS). Parameters measured were transepidermal water loss (TEWL) and skin corneometer values, indicating degree of hydration. Treatment of surfactant-damaged skin with the test cream for 14 days promoted barrier recovery, as observed as a decrease in TEWL. Skin corneometer values also normalized more rapidly during the treatment. In normal skin, use or the test cream significantly reduced TFWL after 14 days of treatment, and irritant reactions to SLS were, significantly decreased. Skin corneometer values increased after only 1 application and remained elevated after 14 days. In conclusion, the accelerated rate of recovery of surfactant-damaged skin and the lower degree of SLS-induced irritation in normal skin treated with the test cream may be of clinical relevance in attempts to reduce contact dermatitis due to irritant stimuli.     

The irritant potential of n-propanol (nonanoic acid vehicle) in cumulative skin irritation: a validation study of two different human in vivo test models

Background/purpose: Human in vivo cumulative irritation tests with low‐grade irritants simulate real‐life exposure to skin irritants. The test outcome depends not only on the substance tested but also on the design of the assay. More than one experimental irritant is usually used because chemicals have diverse mechanisms of action on the skin. We used sodium lauryl sulfate (SLS) and nonanoic acid (NON) in three different concentrations plus their vehicles, water and n‐propanol, respectively, to validate our test models and to optimize test concentrations. Methods: Healthy volunteer forearm skin was exposed in two different cumulative test models: a repeated open model (ROAT) and an exaggerated wash test model. ROAT: 10‐min daily exposures for 5+4 days (no irritation on weekend) to SLS 0% (water), 0.5%, 1.0% and 2.0% on the right arm and NON 0% (n‐propanol neat), 10%, 20% and 30% on the left arm. Wash test: induction of irritation by three daily washings for 6 days and maintenance of the dermatitis by two daily washings for 12 days with SLS 0%, 5%, 10% and 15% or NON 0%, 30%, 40% and 50%. Reactions were evaluated clinically and instrumentally (transepidermal water loss, colorimetry and hydration) at sequential time points. Additionally, for the wash test, subjective pain scores were obtained from the volunteers. Results: In the ROAT, n‐propanol exhibited irritation potential at the level of SLS 1.0% and, by visual scoring, was only found to be significantly different from the two highest concentrations of NON (20% and 30%). In the wash test, n‐propanol was much less irritating than SLS, and it could only be distinguished statistically from NON (any concentration) by visual reading. For both test models, n‐propanol, by instrumental measurements, was not significantly different from any NON concentration. Conclusion: In cumulative irritation test assays, n‐propanol appears to be quite irritant itself and may thus be a significant contributor to NON irritation. Moreover, n‐propanol was more irritant in the ROAT compared with the wash test.     

Acute irritant contact dermatitis: recovery time in man

Our understanding of the details of the recovery time of acute irritant contact dermatitis (ICD) is limited. We examined skin reactivity to a model surfactant, sodium lauryl sulfate (SLS). on previous acute ICD and normal sites over time with visual grading and noninvasive instruments. Acute ICD was induced on the upper arms of 18 volunteers (aged 30 to 51 years) by occluded application of 1% SLS for 24 h. Previous ICD and normal sites were provoked by occluded application of 2% or 7.5% SLS 30 min daily 4 consecutive days. Skin reactivity was assessed daily by visual erythema scoring (VES), transepidermal water loss (TEWL), skin color reflectance (SCR) and electrical capacitance (EC). Skin function of previous ICD sites assessed, by VES, TEWL. SCR, and EC did not normalize until 2 weeks later: all parameters of previous ICD returned to normal after 3 weeks. While skin reactivity to 2% und 7.5% SLS showed no differences between previous ICD and normal sites at 4 weeks, differences of irritant reactivity especially 7,5% SLS between previous ICD and normal sites were significant at 3 weeks post-provocation. Our results demonstrate that irritation evaluated with irritant provocation was long-lasting, even though skin functional parameters assessed by various bioengineering instruments returned to normal. Complete recovery of skin function including irritability after acute ICD induced by 1% SLS was achieved approximately 4 weeks later. The date were generated with a model surfactant: it remains to be determined whether similar responses will be noted with chemicals of different physicochemical properties.     

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.