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PubMed1995

Use of human skin recombinants as an in vitro model for testing the irritation potential of cutaneous irritants.

Two human skin recombinants, the epidermis reconstructed on the deepidermized dermis (RE-DED) or on fibroblast-populated collagen matrix (Living Skin Equivalent, LSE), were used to study the irritating effect of sodium lauryl sulfate (SLS). The extent of cytotoxicity induced after a 24-hour exposure period to increasing concentrations of SLS (0-5%) was evaluated on the basis of (1) morphological perturbations, (2) changes in the expression of differentiation-specific protein markers (keratin 1, 10, 6, 16, involucrin and transglutaminase), (3) cell membrane integrity (LDH leakage) and (4) release of proinflammatory mediators (PGE2, IL-1, IL-6 and IL-8). SLS induced significant changes in epidermal morphology and changes in the expression and localization of differentiation-specific protein markers when applied topically in concentrations higher than 1% on RE-DED and higher than 0.1% on LSE. The exposure of both human skin recombinants to SLS resulted in a dose-dependent release of LDH, PGE2 and IL-1 alpha and in an increase in keratinocyte intracellular IL-1 levels. Upon application of 5% SLS on RE-DED the total (intra- and extracellular) IL-1 levels remained high but due to cell damage the intracellular IL-1 level was markedly decreased and the extracellular IL-1 level increased. Similar observations have been made with LSE after application of 0.5% SLS. However, with LSE the extracellular IL-1 alpha levels were found to be about 100 times lower than those measured with RE-DED. Exposure of LSE to SLS induced a marked increase of IL-6 production in fibroblasts incorporated in the collagen matrix. Contrary to LSE, both intra- and extracellular levels of IL-6 were low in unexposed controls and were only marginally modulated by the exposure of the RE-DED to SLS. In addition, a dose-dependent increase in IL-8 release was observed upon application of SLS on RE-DED. The results of the present study indicate that concentrations of SLS required to induce epidermal irritancy in vitro approximate those inducing irritation in human skin in vivo. All parameters used in the present study for evaluation of toxicity can serve as useful endpoints for screening of contact skin irritancy in vitro. Compared to RE-DED, the LSE seems to be more susceptible to SLS. The differences in sensitivity between LSE and RE-DEd can be ascribed to reported differences in their stratum corneum barrier function.

Adult↗

PubMed1988

Sjögren-Larsson syndrome. Impaired fatty alcohol oxidation in cultured fibroblasts due to deficient fatty alcohol:nicotinamide adenine dinucleotide oxidoreductase activity.

Lipid metabolism was studied in cultured skin fibroblasts from patients with the inherited disorder, Sjögren-Larsson syndrome (SLS). Intact SLS fibroblasts incubated in the presence of [1-14C]palmitate accumulated more radioactive hexadecanol than did normal cells, whereas incorporation of radioactivity into other cellular lipids was unaltered. The hexadecanol content of SLS fibroblasts was abnormally elevated. Hexadecanol accumulation was not due to increased fatty alcohol synthesis nor its deficient utilization for glycerol ether synthesis. The half-life of intracellular hexadecanol loaded into SLS fibroblasts was increased (70 min) compared with normal (15 min), and intact SLS fibroblasts showed impaired oxidation of [14C]-hexadecanol to fatty acid. Fatty alcohol:NAD+ oxidoreductase, the enzyme catalyzing this reaction, was deficient in SLS fibroblasts. Mean total activity in SLS fibroblasts (n = 5) was 13% of that in normal fibroblasts, and palmitoyl CoA-inhibitable activity was 1% of normal. Fibroblasts from two obligate SLS heterozygotes had enzyme activities intermediate between that in normal fibroblasts and individuals with SLS. These results suggest that the primary defect in SLS is deficiency of fatty alcohol:NAD+ oxidoreductase. SLS represents the first inherited disorder in man associated with an isolated abnormality in fatty alcohol metabolism.

3-Hydroxyacyl CoA Dehydrogenases↗

PubMed1993

Influence of sodium lauryl sulphate on 2,4-dinitrochlorobenzene-induced lymph node activation.

The influence of the anionic surfactant sodium lauryl sulphate (SLS) on the ability of the contact allergen 2,4-dinitrochlorobenzene (DNCB) to provoke draining lymph node cell proliferative responses, a correlate of skin sensitizing potential, has been examined in mice. Topical application of 10% SLS with 0.1% DNCB caused a more vigorous proliferative response than did exposure to 0.1% DNCB alone. Lower concentrations (0.1% or 1%) of SLS were ineffective and 10% SLS failed to influence proliferative responses to higher concentrations (0.5% or 1%) of DNCB. Using an in vitro model for measurement of percutaneous absorption 10% SLS was shown not to increase the skin penetration of 0.1% DNCB. We therefore examined the influence of SLS on the accumulation of dendritic cells (DC) in lymph nodes draining the site of exposure, an important early event during the induction phase of skin sensitization. The frequency of DC in draining nodes was measured following topical application of SLS, DNCB or a combination of both. Epicutaneous exposure to 0.1% DNCB caused only a modest increase in the number of lymph node DC. However, 10% SLS or a mixture of 10% SLS with 0.1% DNCB each resulted in a significant elevation of DC numbers. It is proposed that SLS augments the skin sensitizing potential of sub-irritant concentrations of DNCB via an increase in the number of immunostimulatory DC which reach the draining nodes.

Administration, Cutaneous↗

PubMed1997

Sodium lauryl sulfate and triclosan: in vitro cytotoxicity studies with gingival cells.

Triclosan and sodium lauryl sulfate (SLS) are antimicrobial agents used, both singularly and in combination, in dentifrices and mouth-rinses. Studies by Waaler et al. (Scand. J. Dent. Res. 101 (1993) 192-195) with human volunteers showed that the adverse side-effects induced by SLS in mouth-rinses, i.e. desquamation of oral epithelium and a burning sensation, were lessened by the addition of triclosan. However, Baert et al. (Int. J. Exp. Pathol. 77 (1996) 73-78) showed that triclosan did not protect the hamster cheek pouch mucosa from irritation caused by SLS. The studies presented herein further evaluated, using a cell culture system, the triclosan-SLS interaction. The in vitro cytotoxicities of triclosan and SLS, alone and in combination, were determined with human gingival S-G epithelial cells and GF fibroblasts. The 24-h midpoint (NR50) cytotoxicity values towards the S-G cells were 0.052 mM triclosan and 0.0075% SLS and for the GF fibroblasts the respective values were 0.095 mM triclosan and 0.0127% SLS. Both agents at their NR50 values induced vacuolization. Coexposures of triclosan and SLS were additive in their cytotoxicities towards the S-G epithelial cells and GF fibroblasts. Pretreatment with triclosan potentiated the toxicity of a subsequent exposure of SLS to the S-G cells; a similar pretreatment of the GF fibroblasts with triclosan had no effect on a subsequent challenge with SLS.

Anti-Infective Agents, Local↗

PubMed2005

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.

Adult↗

PubMed1996

Pre-treatment of nickel test areas with sodium lauryl sulfate detects nickel sensitivity in subjects reacting negatively to routinely performed patch tests.

A fair % of patients with a clinical history of nickel allergy show negative patch test results. To improve the response rate to NiSO4 5% pet. patch tests, a testing procedure utilizing pre-treatment of the test area by a 24-h application of sodium lauryl sulfate (SLS) was introduced. 46 women with a clinical history of nickel sensitivity, who exhibited negative reactions to nickel sulfate 5% pet. patch tests, were studied. Patients underwent 6 patch tests on adjacent sites on the volar surface of the forearms. 4 patch tests were performed with a 72-h application of 40 mg nickel sulfate 5% pet. While 1 of these patch tests served as control, 3 test areas underwent 24-h pre-treatment with 40 microliters SLS, 1 with 0.1% and 2 with 0.5% solution. To evaluate differences in the reactivity to SLS plus nickel sulfate related to the site on the forearm, 0.5% SLS pre-treatment was performed both on a proximal and on a distal test site. At the 72-h evaluation, 19 subjects out of 46 showed positive reactions to nickel sulfate 5% pet. at skin sites pre-treated with 0.1% SLS, whereas 23 patients reacted positively at 0.5% SLS pre-treated areas. Echographic values of skin thickness and of hypo-echogenic dermal areas at positive pre-treated nickel test areas were higher than at control test areas, confirming the clinical evidence of an increased response to NiSO4 after SLS pre-treatment. The inflammatory reaction, as evaluated clinically and echographically, was much higher at distal skin areas (0.1% SLS and distal 0.5% SLS) than at proximal 0.5% SLS ones.

Adult↗

PubMed1997

Triclosan inhibits sodium lauryl sulphate-induced changes in expression of cytokeratin genes in hamster cheek pouch epithelium.

Triclosan is known to reduce the untoward side effects of sodium lauryl sulphate (SLS). The aim of the present study was to determine whether triclosan can inhibit SLS-induced changes in expression of cytokeratin (CK) genes in hamster cheek pouch epithelium. With a hybridohistochemical technique, using specific human cRNA probes, hamster CK mRNAs were identified by immunological detection of heterologous hybrids. In contrast to application of SLS-containing paste, application of paste containing SLS together with triclosan produced no marked changes in expression and distribution patterns of CK mRNAs, compared to the normal cheek pouch epithelium. Therefore, we may accept that triclosan inhibits the effect of SLS on CK gene expression. However, the mechanism of this protection remains elusive. Conversely, the epithelial hyperplasia induced by application of SLS was histologically identical to that induced by application of SLS and triclosan. This suggests that the changes in CK gene expression identified in the present study are not a simple consequence of epithelial hyperplasia, but rather are specific to the irritating agent. Establishment of the fact that SLS may influence gene expression, and that this may be prevented by triclosan, may be helpful in research on the cytological effects of SLS and the elucidation of protection mechanisms of triclosan against side effects of SLS.

Animals↗

PubMed2002

Antibodies against a synthetic peptide of SagA neutralize the cytolytic activity of streptolysin S from group A streptococci.

Virtually all group A streptococci (GAS) produce streptolysin S (SLS), a cytolytic toxin that is responsible for the beta-hemolysis surrounding colonies of the organisms grown on blood agar. SLS is an important virulence determinant of GAS, and recent studies have identified a nine-gene locus that is responsible for synthesis and transport of the toxin. SLS is not immunogenic; thus, no neutralizing antibodies are evoked during the course of natural infection. In the present study, we show that a synthetic peptide containing amino acid residues 10 to 30 of the putative SLS (SagA) propeptide [SLS(10-30)] coupled to keyhole limpet hemocyanin evoked antibodies in rabbits that completely neutralized the hemolytic activity of the toxin in vitro. Inhibition of hemolysis was reversed by preincubation of the immune serum with soluble, unconjugated peptide, indicating the specificity of the antibodies. In addition, antibodies that were affinity purified over an SLS(10-30) peptide column completely inhibited SLS-mediated hemolysis. The SLS(10-30) antisera did not opsonize group A streptococci; however, when combined with type-specific M protein antisera, the SLS antibodies significantly enhanced phagocytosis mediated by M protein antibodies. Thus, we have shown for the first time that it is possible to raise neutralizing antibodies against one of the most potent bacterial cytolytic toxins known. Our data also provide convincing evidence that the sagA gene actually encodes the SLS peptide of GAS. The synthetic peptide may prove to be an important component of vaccines designed to prevent GAS infections.

Amino Acid Sequence↗

PubMed1991

Sjögren-Larsson syndrome. Deficient activity of the fatty aldehyde dehydrogenase component of fatty alcohol:NAD+ oxidoreductase in cultured fibroblasts.

Sjögren-Larsson syndrome (SLS) is an inherited disorder associated with impaired fatty alcohol oxidation due to deficient activity of fatty alcohol:NAD+ oxidoreductase (FAO). FAO is a complex enzyme which consists of two separate proteins that sequentially catalyze the oxidation of fatty alcohol to fatty aldehyde and fatty acid. To determine which enzymatic component of FAO was deficient in SLS, we assayed fatty aldehyde dehydrogenase (FALDH) and fatty alcohol dehydrogenase in cultured fibroblasts from seven unrelated SLS patients. All SLS cells were selectively deficient in the FALDH component of FAO, and had normal activity of fatty alcohol dehydrogenase. The extent of FALDH deficiency in SLS cells depended on the aliphatic aldehyde used as substrate, ranging from 62% of mean normal activity using propionaldehyde as substrate to 8% of mean normal activity with octadecanal. FALDH activity in obligate SLS heterozygotes was partially decreased to 49 +/- 7% of mean normal activity using octadecanal as substrate. Differential centrifugation studies in fibroblasts indicated that this FALDH enzyme was largely particulate; soluble FALDH activity was normal in SLS cells. Intact SLS fibroblasts oxidized octadecanol to fatty acid at less than 10% of the normal rate, but oxidized free octadecanal normally, suggesting that the FALDH affected in SLS is chiefly involved in the oxidation of fatty alcohol to fatty acid. These results show that the primary enzymatic defect in SLS is the FALDH component of the FAO complex, which leads to deficient oxidation of fatty aldehyde derived from fatty alcohol.

Alcohol Oxidoreductases↗

PubMedDate not supplied

Evaluation of skin susceptibility to irritancy by routine patch testing with sodium lauryl sulfate.

Irritant patch testing with sodium lauryl sulfate (SLS) will become more and more a routine test determining skin susceptibility in men. Recently, it has been shown that for practical reasons, irritant SLS patch testing can take place on the back simultaneously with a routine allergic patch test to other contact allergens. However, SLS patch testing has mostly been performed on the forearm in studying experimental skin irritation so far. The aim of this study was to determine whether there is a relationship in skin response to aqueous SLS (0.125%; 0.25%; 0.5% and 1.0%) between the forearm and the back assessed by visual scoring and measurement of transepidermal water loss (TEWL). We found a pronounced reaction of the forearm compared to the back. TEWL values as well as visual scores correlated well with SLS concentration. There was also a high correlation in visual scoring between the forearm and the back. Based on test sensitivity and specificity we suggest a 48 hrs patch test for routine screening with 0.5% SLS on the forearm evaluated by TEWL measurement or visual scoring 24 hrs after patch removal. A mild erythema (scored as < or =1) is considered to be normal. If for practical reasons, the SLS patch is placed on the back simultaneously with the allergic patch test, 0.5% SLS may be sufficient, too. TEWL measurement so far provides a reliable method and will certainly be necessary for experimental studies on irritant skin reactions, particularly when different SLS concentrations are used. After a 48 hrs patch test with SLS 0.5% TEWL measurement should be performed at 72 hrs. A value of < or =31.6 g/m(2)hr seems to follow the normal distribution.

Back↗

PubMed2003

Effects of a betaine-containing toothpaste on subjective symptoms of dry mouth: a randomized clinical trial.

Our aim was to study the effects of mildly flavoured sodium lauryl sulphate (SLS)-containing and detergent-free toothpastes with and without betaine (BET) on subjective symptoms of dry mouth in a randomised clinical trial. BET is an osmoprotectant that reacts with molecules to supply the surface with a water coating that protects cells from surfactants. Twenty-seven xerostomic patients and 18 healthy controls took part in the randomised, double-blind clinical trial with a crossover design. Three mildly flavoured toothpastes: (1) 4% BET, (2) 1% SLS and 4% BET, and (3) 1% SLS were used for six weeks each. The reference or washout paste contained neither SLS nor BET. The subjects' dental appointments were at the beginning of the trial and before and after the use of each toothpaste. At each appointment, the subjects were interviewed about subjective sensations of dry mouth (Visual Assessment Scoring (VAS) Index). The subjects did not report any adverse effects in connection with the use of the toothpastes. The VAS scores for lip dryness and eating difficulties were significantly lower for the BET paste (lip dryness: BET<BET+SLS; p < 0.005 and eating difficulties: BET<BET+SLS; p = 0.02; BET<reference; p = 0.003). The BET paste relieved dry mouth symptoms in 44% of the xerostomic patients, the corresponding figures for the other pastes being BET+SLS 22% (p = 0.002 as compared with BET), SLS 18% (p = 0.022), and reference 7% (p = 0.000). In conclusion, all the mildly flavoured toothpastes used in this study were well accepted by the xerostomic subjects. Thus, other toothpaste components may be more mucosa-irritating than just SLS, or else they enhance the effect of SLS. The detergent-free, BET-containing toothpaste appeared to be associated with relief of some symptoms of dry mouth.

Analysis of Variance↗

PubMed1995

Radial spread of sodium lauryl sulfate after topical application.

PURPOSE: Since topical application of sodium lauryl sulfate (SLS) has been reported to elevate transepidermal water loss and decrease skin capacitance in areas immediately adjacent to the applied site, studies were carried out to quantify the extent of radial spread of SLS below a topically exposed site in a hairless rat model. METHODS: Fixed sites were demarcated and the levels of SLS measured around the applied site in the epidermis, dermis and the subcutaneous tissues. Underlying deep tissue penetration and radial spread of SLS in the presence and absence of a vasoconstrictor, phenylephrine, was also quantified. RESULTS: In a typical 24 hour study, the radial spread of SLS was observed to a distance of approximately 0.75 cm from the applied site. The use of phenylephrine (1:20000), did not significantly enhance either the local underlying tissue (apart from underlying epidermis) concentration or radial spread of SLS relative to no vasoconstrictor treatment. CONCLUSIONS: Given that SLS impairs barrier function of the skin, its radial spread could be explained by a passive diffusion process. Vasoconstrictor did not remarkably alter SLS penetration and radial spread possibly due to the competing effects of vasodilation (caused by SLS) and vasoconstriction (caused by phenylephrine).

Administration, Topical↗

PubMed2000

RNA-based mutation screening in German families with Sjögren-Larsson syndrome.

Sjögren-Larsson syndrome (SLS) is a rare autosomal recessively inherited disorder characterised by mental retardation, spasticity and ichthyosis. SLS patients have a profound deficiency in fatty aldehyde dehydrogenase (FALDH) activity. The human cDNA of FALDH has been shown to map to the SLS locus on chromosome 17p11.2. Here we describe a method based on reverse transcriptase-polymerase chain reaction (RT-PCR) and protein truncation test to identify mutations in the FALDH gene in nine German SLS families. Using this detection system both disease-causing mutations were found in eight of the nine SLS families examined (17/18 chromosomes). Seven different mutations were identified: an exon 2 skipping due to exon 2 splice donor mutation; two different exon 3 splice donor mutations resulting in combined exon 2 and 3 skipping; a 906delT deletion in exon 6; a genomic deletion of about 6 kb including exon 9; a 1277T > G transversion resulting in a Leu426Ter nonsense mutation; and a 1297delGA deletion. Two of the mutations identified, the genomic exon 9 deletion and the 906delT in exon 6 affected five out of seven SLS patients from a small region of Northern Bavaria. Therefore these two mutations accounted for 71% (10/14 chromosomes) of Bavarian SLS alleles and so far have not been described in SLS families from other countries. Our findings do not support our 'historical' hypothesis, that a possible region clustering in Northern Bavaria could be due to the presence of Swedish soldiers during the 30 Years War (1618-1648), but suggest that two mutations causing SLS syndrome originated in Northern Bavaria.

Aldehyde Oxidoreductases↗

PubMed2002

Inhibitory effects of Leopoldine spa water on inflammation caused by sodium lauryl sulphate.

BACKGROUND: Sulphur mineral waters may have anti-inflammatory effects on human skin. We evaluated the anti-inflammatory effects of Leopoldine spa water, a salso-sulphate water (Table 1), on human skin tested with sodium lauryl sulphate (SLS). PATIENTS AND METHODS: Ten healthy, Caucasian volunteers 28-53 years old were enrolled in this study. SLS was tested on the right arm, in two concentrations (0.5% and 1%) dissolved in both double-distilled nonpyrogenic water and Leopoldine spa water in four separate test tubes; 0.02 mL of each solution was applied via the testing apparatus (Vand der Bend chambers, four squares measuring 1 x 1 cm), which was fixed and remained in contact with the skin surface. The anti-inflammatory effect was measured via the variations of redness (chromometry, parameter a*), using a Minolta CR 200 chromometer. RESULTS: At base condition the values of a* of the areas that were tested ranged from 7.11 to 9.30 with a mean of 7.97. In regard to the reaction caused by SLS dissolved in double-distilled water, the values of a* ranged from 8.98 to 9.53, mean 9.24, for 0.5% SLS and from 12.81 to 14.33, mean 13.59, for 1% SLS. The a* values for the cutaneous reaction caused by SLS dissolved in Leopoldine spa water ranged from 7.22 to 9.60 (mean 8.20) for 0.5% SLS and from 10.8 to 12.36 (mean 11.68) for the 1% SLS. CONCLUSIONS: These data show the potential anti-inflammatory effects of Leopoldine mineral water on human skin affected by modest inflammatory reactions caused by the direct application of the chemical irritant SLS. Leopoldine spa water can, thus, be considered a natural therapeutic alternative for the treatment of inflammatory skin conditions.

Adult↗

PubMed1993

Efficacy of skin barrier creams (III). The repetitive irritation test (RIT) in humans.

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 skin colour by 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 test 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1994

Sodium lauryl sulphate penetration in an in vitro model using human skin.

Because of their ability to impair the skin barrier function, detergents constitute a major risk factor for the development of irritant contact dermatitis. Sodium lauryl sulphate (SLS) is a commonly used detergent for experimental studies within the area of irritant contact dermatitis. In the present study, penetration of S35-labelled SLS was studied in an in vitro model using human cadaver skin. The investigations showed that SLS is capable of permeating the skin barrier when applied under occlusion. SLS could be detected in the dermis and the amount of SLS found here was shown to depend on the dose of SLS applied on the skin. Penetration of SLS continued after removal of the SLS applied as a patch test on the skin surface. Considerable inter-individual variation in the penetration of SLS was demonstrated between different donors.

Adult↗

PubMed1999

Does sodium lauryl sulfate concentration vary with time?

When performing skin irritation tests with sodium lauryl sulfate (SLS), the quality of the test solution is of major importance for the reproducibility and comparability of the results. The influence of 4 different storage parameters (concentration, duration, temperature, material of the storage vials) on the stability of aqueous SLS solutions was investigated under non-sterile conditions. SLS solutions at 5 different concentrations (0.001%, 0.01%, 0.1%, 0.5%, 1%) were analysed by mobile phase ion chromatography. Analyses were performed after a storage time of 3 h, 1 week, and 4 weeks. Storage was carried out at different temperatures: -18 degrees C, 6 degrees C, and 23 degrees C. The storage containers were of 2 different materials (glass and polypropylene). After a storage of 1 week, no decrease in SLS concentration was observed, regardless of the chosen conditions. After 4 weeks at 6 degrees C and 23 degrees C, the SLS concentration was found to be significantly decreased for the 2 lowest concentrations (0.001% and 0.01%). At higher concentrations and lower temperatures, no decrease in SLS concentration had occurred. In parallel to the loss of SLS, contamination with bacteria was found in the solutions, especially at the 2 lowest concentrations. Bacterial growth was not observed at higher concentrations. The possibility of biodegradation of SLS has to be taken into account, especially when dealing with low concentrations of SLS.

Allergens↗

PubMed2006

Increased permeability for polyethylene glycols through skin compromised by sodium lauryl sulphate.

In this in vivo human study we assessed the influence of skin damage by sodium lauryl sulphate (SLS) on percutaneous penetration of polyethylene glycols (PEGs) of different molecular weights (MW). Percutaneous penetration of PEGs was determined using tape stripping of the stratum corneum (SC). The forearm skin of volunteers was pretreated with 5% w/w SLS for 4 h, and 24 h later patches with PEGs were applied for 6 h. The penetration parameters were deduced by data regression to Fick's law for unsteady-state diffusion. The trans-epidermal water loss (TEWL) increased after SLS treatment from 6.3 +/- 2.1 to 17.9 +/- 8.7 g/m(2)/h. The diffusion coefficient for all PEGs was increased in the SLS-damaged skin. The increase was smaller for higher MW. In addition, the partition coefficient of PEGs between SC and water was larger in the SLS-compromised skin and showed a tendency to increase with MW. The permeability coefficient decreased gradually with increasing MW of PEGs in both control and SLS-compromised skin. SLS caused a threefold increase in the permeability coefficient for all MWs ranging in control skin from 0.34 to 0.70 x 10(-5) cm/h and in the SLS-compromised skin from 1.20 to 2.09 x 10(-5) cm/h for MW of 590-282 Da. The results of this study show the deleterious effect of SLS on the skin barrier for hydrophilic PEGs. A defective skin barrier will facilitate absorption of other chemicals and local skin effects.

Adolescent↗