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.     

Bioengineering measurements of barrier creams efficacy against toluene and NaOH in an in vivo single irritation test

Background/aims: By now, only a few models have been published with the goal of testing barrier creams in vivo in humans. The aim of this study was to evaluate with a single irritation test, barriers creams in humans against a lipophilic and a hydrophilic irritant, toluene and NaOH, respectively.
Methods: Both irritants were applied for 15 min after pretreatment of the skin with barrier creams. Non-invasive bioengineering methods, such as skin colorimetry (a*) and cutaneous blood flow (CBF) measurements were used to assess product protection.
Results: After toluene application on control sites, the irritation appeared quickly (T_max=3 min after patch removal), was significant (+5-6 units for a* and+80% for CBF) and did not return to base value within 1 h. Skin irritation after NaOH application, as measured by a*, was less important (+2 units) and occurred later ( T "max=40 min after patch removal). For this irritant, CBF response was minor and variable. When testing barrier properties of the products, none of them were able to prevent the skin erythema induced by toluene. Against NaOH, one barrier cream as well as petrolatum and a fatty cream protected the skin significantly.
Conclusion: The present study points out the unsatisfactory effectiveness of several commercially available barrier creams claimed to protect against lipophilic or hydrophilic irritants.     

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.     

Cutting oil dermatitis on guinea pig skin

We assessed the effect of repeated application of cutting oil on 9 guinea pigs' skin by visual scoring and skin water vapour loss measurement. The visual scores (severity score) were significantly higher on skin treated with cutting oil (positive control) compared to untreated skin (negative control). The corresponding mean SVL values were also significantly higher. We also assessed the effect of 2 barrier creams on the 9 guinea pigs' skin treated with cutting oil. The visual scores on skin treated with either barrier cream were significantly higher than positive control skin. The corresponding mean SVL values on skin treated with either barrier cream were also higher (not statistically significant). It appeared that the 2 barrier creams did not confer protection against the irritant effect of the cutting oil. On the contrary, barrier creams appeared to exacerbate the irritant effect of cutting oil.     

Efficacy of skin barrier creams (IV). The repetitive irritation test (RIT) with a set of 4 standard irritants

An improved human model for the quantification of skin barrier creams (BCs) is described. In contrast to the previously published procedure, the back, instead of the forearm, and a total of 4 irritants are used. Due to the larger area, 3 BC formulations can be simultaneously compared to the control field, which receives the irritant only, without BC-pretreatment. On 10 human volunteers, the irritants 10% sodium lauryl sulfate (SLS), 1% sodium hydroxide (NaOH), 30% lactic acid (LA) and undiluted toluene (TOL) were applied via large Finn Chambers for 30 min, 5 × during the 1st week and 4 × during the 2nd week. Taktosan Salbe (water-in-oil emulsion) and RAWI Speerschutzcreme (oil-in-water emulsion) were applied 30 min before contact with the irritants. In order to asses reproducibility and interindividual variation, the BC RAWI was tested in duplicate. Irritant cutaneous reactions were quantified by 4 parameters: erythema score, transepidermal water loss, blood flow volume and stratum corneum hydration by measuring capacitance. The results showed marked differences in efficacy. Taktosan significantly suppressed irritation by SLS, NaOH and LA, which was apparent in nearly all parameters. RAWI caused significant inhibition of SLS irritation, and a positive trend against NaOH and LA was observed. Both BCs failed against TOL. The results of duplicate testing with RAWI showed good reproducibility. The dogma that oil-in-water emulsions are primarily effective against lipophilic irritants, and water-in-oil emulsions against hydrophilic irritants, needs to be re-evaluated on the basis of our findings. This model seems to have potential for further studies on BCs and might elucidate the complex interaction of BCs with 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.     

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.     

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.     

Experimentally induced chronic irritant contact dermatitis to evaluate the efficacy of protective creams in vivo

BACKGROUND: Widely accepted in vivo models to evaluate the efficacy of protective creams (PCs) are still missing. OBJECTIVE: The effect of petrolatum's ability to protect against irritation was tested in a repetitive irritation test to optimize the concentration of irritants against which PCs are tested and to evaluate the necessary cumulative application time. METHODS: On 20 healthy volunteers, the irritants (sodium lauryl sulfate 5% vs 10%, sodium hydroxide 0.5% vs 1%, lactic acid 20% vs 30%, and toluene undiluted) were applied daily for 2 weeks on the ventral forearms after 30 minutes of pretreatment with petrolatum. The irritant cutaneous reactions were quantified by erythema score, transepidermal water loss, and chromametry. RESULTS: For petrolatum, a significant protective effect was obtained against irritation by sodium lauryl sulfate, sodium hydroxide, and toluene in different degrees. Less efficacy was observed against lactic acid. CONCLUSION: It was concluded that a 1-week period of cumulative irritation is enough to evaluate the efficacy of PCs against most irritants, even if lower concentrations of irritants are used.     

Skin protection against ionized cobalt and sodium lauryl sulphate with barrier creams

853 individuals who are still working or had previously worked in hard metal manufacture were examined and selected for patch tests with materials from their working environment including metal allergens. The majority of the individuals with positive test reactions to cobalt chloride were retested with serial dilutions of cobalt chloride and with the same serial dilutions after preparation of the skin with a layer of barrier or emollient cream used for hand care in this factory. The irritant effect of sodium lauryl sulphate (SLS) was similarly investigated. The barrier and emollient creams did not give any protection against cobalt chloride or sodium lauryl sulphate. In fact they seemed to enhance the penetration of cobalt ions. Their use in protection against metal allergens and cutting fluids is questionable.     

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.     

Skin reactions to irritants assessed by polysulfide rubber replica

Skin damage after application of experimental irritants was evaluated under blind conditions and by the use of polysulfide rubber replica. Closed patch tests with 7 different irritants, solvents and empty chambers were applied to 16 volunteers, and the skin damage was evaluated visually and by a replica technique after 24, 48 and 96 h. We found that 3 of the irritants (sodium lauryl sulphate, hydrochloric acid and croton oil) were capable of causing specific and significantly different patterns of skin damage. The patterns could be divided into papular (hydrochloric acid, croton oil) and non-papular (sodium lauryl sulphate, sapo kalinus, sodium hydroxide) types. Nonanoic acid caused a non-paular pattern, but propanol, used as a solvent, by itself also produced a non-papular pattern. The time between application of the irritant and appearance of the characteristic alteration in the skin surface differed, depending on the irritant applied.     

Cumulative irritancy in the guinea Pig from low grade irritant vehicles and the angry skin syndrome

A 4-week open cumulative irritancy test in guinea pigs discriminated between two low grade irritant vehicles, nonionic base (anhydrous) and hydrophilic ointment. The procedure might be useful as a predictive test for low grade irritants. The angry skin syndrome was established in the guinea pigs by one Freunds complete adjuvant intradermal injection on day 0, or by daily open applications of 10% sodium lauryl sulfate in petrolatum to the neck area of the animals.     

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.     

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.     

Water protective effect of barrier creams and moisturizing creams: a new in vivo test method

Frequent exposure to water is an important risk factor for the development of irritant hand eczema. Evaluation of cream efficacy in protecting against water is difficult. A new non-irritant, non-invasive method is introduced, based on evaluation of colour intensities when an aqueous solution of crystal violet is applied to the skin, after pretreatment with different creams. By skin reflectance measurement, differences in colour intensity were objectified. Measurements of transepidermal water loss were also performed. 2 barrier creams and a moisturizer were tested on the dorsal and volar aspects of the handy One barrier cream contained silicone the other solid particles. The moisturizer had a high content of lipid. In one experiment, the immediate effect of the cream in protecting against water was evaluated. In a second experiment, the water resistancy of the creams was tested, using a standard water immersion procedure (4X20 min). The barrier cream with particles gave the best immediate protection (dorsal 76% volar 69%). The moisturizer was intermediately protective (dorsal 57% volar 34%) while very link protection was found for the silicone-containing cream (dorsal 16% volar 10%). The water immersion procedure resulted in only minor changes in protection for each cream. When comparing transepidermal water loss in the treated areas with pretreatment values, a reduction was recorded only for the particle-containing barrier cream. The colour method described may be used as a quick and easy test of the protective effect of creams against water.     

Experimentally-induced irritant contact dermatitis

Patch testing with 7 irritants has been performed on a panel of 42 healthy volunteers, with the aim of determining concentrations which would induce mild to moderate reactions in at least 75% of individuals tested. The irritants studied and their optimum concentrations were as follows: benzalkonium chloride, 0.5%; sodium lauryl sulphate, 5%; croton oil, 0.8%; dithranol, 0.02%; nonanoic acid, 80%; propylene glycol, 100%; sodium hydroxide, 2%. Responder rates lower than 75% had to be accepted for benzalkonium chloride and sodium hydroxide in order to prevent overly severe reactions, whilst propylene glycol proved to have only marginal irritant properties.     

Multicentre study for the development of an in vivo model to evaluate the influence of topical formulations on irritation

Although skin protective products to prevent irritant skin reactions are in wide use, neither standardized test models to prove differences in efficacy exist, nor has the quality or the reproducibility of results been evaluated in a multicentre approach. This should be mandatory when developing or testing skin care products. Therefore, we have designed a multicentre study in an approach to find a standardized test procedure for the evaluation of skin protective products. In this irritation study, a repeated short-time occlusive irritation test (ROIT) with a standardized protocol has been evaluated in 2 phases (12 days and 5 days protocol) in 4 (n=20) respectively 6 (n=33) skilled centres. The skin reaction was induced by 2 irritants (0.5% aq. SLS and toluene, 2x a day for 30 min). Its modification by 3 different cream bases with different hydrophilicity was analyzed. The irritation was monitored by bioengineering methods (TEWL measurement, colorimetry) and by clinical scoring. The evaluation showed that significant results could already be achieved with the 5-day protocol. Furthermore, in spite of the expected inter-centre variations due to heterogeneity of the individual threshold of irritation, interpretation of clinical score, and inter-instrumental variability, the ranking of the vehicles regarding reduction of the irritant reaction was consistent in all centres.     

Multiple parameter assessment of skin irritancy

In a previously developed guinea pig model for the study of skin irritancy, the irritant skin reactions caused by repeated open applications of low concentrations of sodium lauryl sulphate (SLS) have been studied macroscopically and microscopically. 2 new assessment methods, evaporimetry, which reflects the water barrier function of stratum corneum, and laser Doppler flowmetry to measure the cutaneous blood flow, have been added and compared with the existing methods of assessment in the model. In the present study of the irritant reaction caused by 1% SLS in 9 test animals, the 5 assessment parameters all showed values which, compared to control untested skin, increased progressively over the 3 days of application. In the assessment of skin irritancy, both evaporimetry and laser Doppler flowmetry have been shown to be useful non-invasive tools which can be quickly and reproducibly performed.