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.     

Irritant susceptibility and weal and flare reactions to bioactive agents in atopic dermatitis. II. Influence of season

Many atopic dermatitis (AD) patients have exacerbations of their skin disease in winter. These exacerbations may be caused by non-immunological ‘non-specific’ factors, such as low sun exposure and low temperature. To date, the influence of season on non-specific skin reactivity in AD has not been studied. The aim of the present investigation was to assess the influence of season on two skin parameters which may be used as quantitative measures of non-specific skin reactivity in AD: (i) susceptibility to repeated epicutaneous irritant (sodium lauryl sulphate, SLS) exposure, and (ii) weal and flare responses to intracutaneous injection of bioactive agents (codeine, FMLP, histamine, methacholine, substance P, trypsin). Four of 16 AD patients had dermatitis which was more severe in November than in July. Susceptibility to SLS was increased in November, both in AD patients and in control subjects. AD patients were more susceptible to SLS than control subjects in both July and November, Pre-exposure barrier function and skin hydration were reduced in November. The increased irritant susceptibility in November may be attributed to reduced barrier function, reduced skin hydration, and/or absence of the beneficial effects of ultraviolet light on cellular targets beneath the stratum corneurn, Flare responses to codeine, methacholine, substance P and trypsin were also increased in November compared with July, especially in AD patients. However, smaller Hares were observed in AD patients than in control subjects, in both July and November, Flare values were negatively correlated with dermatitis severity, probably because of down-regulation. Weal responses did not show a clear seasonal variation. Hence, susceptibility to epicutaneous irritants and reactivity to intracutaneousty injected bioactive agents are parameters which may be used to monitor season dependent changes in non-specific skin reactivity.     

Assessment of skin irritancy by 2 short tests compared to acute irritation induced by sodium lauryl sulfate

Irritant contact dermatitis is a very common disease that i. preventable by protective measures The development of screening methods to identify subject with increased susceptibility in irritants is essential in reduce the incidence of this disorder in the workplace On the outlook for such methods. 2 quick non-invasive tests for irritability of the skin were compared to reliable, but time-consuming, patch testing with sodium lauryl sulfate (SLS) In 20 healthy volunteers, 0.5% SLS was applied on the medial 1/3 of the forearm for 23 h in order to induce experimental irritant contact dermatitis. On the same part of the forearm, 3 concentrations of dimethylsulfoxide (DMSO) and a solution of 0.2 mol/1 NaOH were applied for 5 min. Assessment of skin irritability was made by visual scoring and measurement of transepidermal water loss. No correlation between the "Quick tests" and SLS patch testing was found, indicating that tests assess different mechanisms of irritation.     

A dose-response study of irritant reactions to sodium lauryl sulphate in patients with seborrhoeic dermatitis and atopic eczema.

The susceptibility of the skin of patients with seborrhoeic dermatitis to surfactant irritation was investigated and compared to that of a group of normal subjects and patients with a history of atopic eczema. Responses to six concentrations of sodium lauryl sulphate (SLS), applied to forearm skin, were assessed clinically and measured by laser Doppler flowmetry. Analysis of dose-response curves showed statistically significant increased susceptibility to SLS-induced irritation in patients with seborrhoeic dermatitis and atopic eczema compared with normal subjects. Increased susceptibility to chemical irritation may be important in the pathogenesis of seborrhoeic dermatitis.     

Improvement in skin barrier function in patients with atopic dermatitis after treatment with a moisturizing cream (Canoderm)

Patients with atopic skin show a defective barrier function both in rough and in clinically normal skin, with an increasing risk of developing contact dermatitis. Moisturizing creams are often used in the treatment of dry skin. The purpose of this study was to investigate the influence of treatment with a urea-containing moisturizer on the barrier properties of atopic skin. Fifteen patients with atopic dermatitis treated one of their forearms twice daily for 20 days with a moisturizing cream. Skin capacitance and transepidermal water loss (TEWL) were measured at the start of the study and after 10 and 20 days. On day 21 the skin was exposed to sodium lauryl sulphate (SLS) and on day 22 the irritant reaction was measured non-invasively. Skin capacitance was significantly increased by the treatment, indicating increased skin hydration. The water barrier function, as reflected by TEWL values, tended to improve (P = 0.07), and the skin susceptibility to SLS was significantly reduced, as measured by TEWL and superficial skin blood flow (P < 0.05). Thus, it seems that certain moisturizers could improve skin barrier function in atopics and reduce skin susceptibility to irritants. The mechanism and the clinical relevance need further investigation.     

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.     

Efficacy of corticosteroids in acute experimental irritant contact dermatitis?

Background/aims: Topical corticoids are used to treat irritant contact dermatitis (ICD) in humans. However, their clinical efficacy remains sub judice. This study was designed to assess the efficacy of low- and medium-potency corticosteroids on irritant dermatitis.
Methods: We induced an acute ICD via open application of sodium lauryl sulphate (SLS) on the hands of subjects. The dorsal side of hands was irritated with 10% SLS five times in one day. Once on day 1 and twice daily on days 2–5, 1% hydrocortisone, 0.1% betamethasone-17-valerate and vehicle cream (petrolatum) were applied subsequently. Visual grading, bioengineering techniques and squamometry were used to quantify skin response.
Results: Corticosteroids were found ineffective in treating the surfactant-induced irritant dermatitis when compared with the vehicle and with the untreated control.
Conclusion: The counterintuitive result (in a relatively realistic and robust model) should be interpreted with caution until verified with other irritants of varying physicochemical properties.     

Skin irritation thresholds in hairdressers: implications for the development of hand dermatitis

BACKGROUND: Individuals vary in their ability to react to irritants. OBJECTIVES: To observe the development of clinical hand dermatitis and sensitization prospectively in trainee hairdressers and to compare this with their irritant threshold to sodium lauryl sulphate (SLS). METHODS: Subjects were patch tested to a limited series of occupational importance and their irritant threshold to SLS was determined; patch testing was repeated 6 months later and subjects were assessed for hand dermatitis. RESULTS: The development of hand dermatitis was associated with a lower irritant threshold. A similar association was not found for sensitization. CONCLUSIONS: The development of clinical dermatitis in prospectively followed subjects with greater irritant reactivity has not previously been identified. The association of greater irritant reactivity with a proinflammatory cytokine polymorphism may partly explain this. Further development of the irritant threshold test could contribute to the identification of non-atopic subjects at risk of occupational skin disease.     

Skin susceptibility of atopic individuals

The relevance of the irritant skin reaction of individuals with an atopic history (atopic dermatitis, rhinoconjunctivitis or atopic asthma) to sodium lauryl sulfate (SLS), a widely used irritant, is still controversial. The aim of this study was to evaluate transepidermal water loss (TEWL) as an indicator of stratum corneum integrity, before and after SLS patch testing, in various groups of atopic individuals with and without atopic dermatitis. 95 volunteers were divided into 4 groups: (1) individuals with active atopic dermatitis; (2) individuals with a history of atopic dermatitis but without active skin lesions; (3) individuals with rhinoconjunctivitis or atopic asthma without any symptoms at the time of testing; (4) healthy individuals serving as controls. The volunteers were patch-tested at the unaffected volar side of the forearm with aqueous SLS 0.5% for 48 h. TEWL was measured before application and after removal of the patch. Individuals with active atopic dermatitis showed a significantly higher TEWL value after SLS and a tendency to a higher basal TEWL as compared to the 3 other groups. There were no significant differences in TEWL between individuals who were classified as atopic but without active dermatitis, individuals with rhinoconjunctivitis or atopic asthma and healthy controls, either at the basal or at the post-SLS measurement. Enhanced skin susceptibility is only present in individuals with active dermatitis. The skin susceptibility of atopic individuals might therefore be increased as soon as the skin becomes eczematous, suggesting a reduced epidermal integrity probably caused by the endogenous atopy and/or respiratory allergens. When interpreting the atopy score in relation to skin susceptibility, the actual condition of the skin should hence be taken into consideration.     

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.     

An evaluation of the relationship between 'atopic skin' and skin irritability in metalworker trainees

Skin hyperirritability to irritants as well as atopy are considered to be predisposing factors for contact dermatitis. The aim of the study was to evaluate whether these predictive factors are independent or whether they are so closely related that one could possibly replace the oilier. 205 metalworker trainees underwent skill examination for skin atopy, including standardised questionnaire, clinical examination of the skin and a series of skin irritability tests. These tests included measurements of transepidermal water loss (TEWL) before and after irritation with 3 different irritants: sodium lauryl sulfate (SLS), dimethylsulfoxide (DMSO) and sodium hydroxide (NaOH). The results of the linear regression analysis demonstrate that skin atopy is not associated with increased skin irritability, as assessed by the irritability testing methods presented.     

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.     

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.     

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.     

Contact thermography for assessment of skin damage due to experimental irritants

Irritant dermatitis after application of experimental irritants was studied by means of contact thermography. Sixteen healthy persons were patch-tested, using the following irritants: Sodium lauryl sulphate, benzalkonium chloride, nonanoic acid, hydrochloric acid, croton oil, sapo kalinus and sodium hydroxide. A main finding was that croton oil after 24 h caused a warm skin lesion, and sodium lauryl sulphate after 96 h caused a cold skin lesion. This study emphasizes the differences in the skin reactions to different irritants.     

Allergic contact dermatitis from di-isodecyl phthatate in a polyvinyl chloride identity band

An animal model for the evaluation of skin protective creams against chemical irritants is described. The irritants were applied daily for 2 weeks to shaved back skin of young guinea pigs: sodium tauryl sulphate (5% aq.: 30 min), sodium hydroxide (0,5% aq.; 2 min). and toluene (20′i. eth.; 2 mint. “The harrier cream was applied 2 h prior to and immediately after exposure to the irritant. Control animals were treated with the irritant only. The irritant reaction was scored on a 4–point scale for erythema and quantified with regard to transepidennal water loss (TEWL) by evaporime-try and skin blood flow volume (BFV) by laser Doppler velocimetry. A total of 90 guinea pigs, consisting of” individual panels of 5 to 10 animals, was tested. While one barrier cream (Slokoderm) significantly suppressed the irritation due 10 sodium lauryl sulphate and toluene, the other (Contra-Alkalh failed to do so and even aggravated the response, which was particularly evident with sodium hydroxide. This model may be useful in developing more effective barrier creams.     

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.     

Efficacy of skin barrier creams

An animal model for the evaluation of skin protective creams against chemical irritants is described. The irritants were applied daily for 2 weeks to shaved back skin of young guinea pigs: sodium tauryl sulphate (5% aq.: 30 min), sodium hydroxide (0,5% aq.; 2 min). and toluene (20'i. eth.; 2 mint. "The harrier cream was applied 2 h prior to and immediately after exposure to the irritant. Control animals were treated with the irritant only. The irritant reaction was scored on a 4–point scale for erythema and quantified with regard to transepidennal water loss (TEWL) by evaporime-try and skin blood flow volume (BFV) by laser Doppler velocimetry. A total of 90 guinea pigs, consisting of" individual panels of 5 to 10 animals, was tested. While one barrier cream (Slokoderm) significantly suppressed the irritation due 10 sodium lauryl sulphate and toluene, the other (Contra-Alkalh failed to do so and even aggravated the response, which was particularly evident with sodium hydroxide. This model may be useful in developing more effective barrier creams.     

Efficacy of a new class of perfluoropolyethers in the prevention of irritant contact dermatitis

Perfluoropolyethers (Fomblin HC products) are chemical non-reactive polymers with special physico-chemical properties that recently showed promise as protective preparations in the prevention of irritant contact dermatitis. We evaluated the efficacy of a new class of perfluoropolyethers (perfluoropolyether phosphate, Fomblin HC/P2) in the prevention of experimentally induced cumulative irritant contact dermatitis if applied prior to irritation. A panel of 20 healthy volunteers was tested with a repetitive irritation test using 4 standard irritants (sodium lauryl sulphate of highest purity, sodium hydroxide, lactic acid and toluene) in a randomized double-blind study. Application sites were assessed clinically and by the use of bioengineering techniques (transepidermal water loss and chromametry). Three gel preparations each containing 5% perfluoropolyether phosphate showed significant efficacy against irritation due to sodium lauryl sulphate and sodium hydroxide, while one test preparation containing 2% showed inferior benefit, indicating a dose-related effect. Preparations containing perfluoropolyether phosphates can be recommended for workplaces with water-soluble irritants. Further studies under real workplace conditions are indicated.     

Influence of irritants on lymph node cell proliferation and the detection of contact sensitivity to metal salts in the murine local lymph node assay

Dimethyl sulfoxide (DMSO) and sodium lauryl sulfate (SLS) are known to cause irritation of the skin, and to enhance the penetration of chemicals into the epidermis. In the present study, the lymph node cell (LNC) proliferative response following exposure to irritants, such as SLS and DMSO, was examined in the marine local lymph node assay (LLNA). Exposure to DMSO or SLS aqueous Solution induced a small increase in lymph node cell proliferation compared with aqueous solution alone. Exposure to SLS in DMSO caused a significant increase in LNC proliferation. Further, the effect of addition of the irritants in a vehicle on the detection of contact sensitivity to metal allergens was examined. Application of potassium dichromate and nickel sulfate in DMSO or SLS aqueous solution caused increases in LNC proliferation. Exposure to metal allergen with SLS in DMSO also induced a significant LNC proliferative response, but did not induce 9 significant increase in stimulation index (increase in ³H-thymidine incorporation relative to vehicle-treated control group). This was because of increased ³H-thymidine incorporation following exposure to SLS-DMSO in the control group. These results suggest that irritants enhance the LNC proliferate responses to metal allergens. The use of SLS in aqueous solution is effective for the detection of sensitivity to water-soluble allergens, such as metal allergens, in the LLNA, as well as the use of DMSO as an application vehicle.