SLS irritation

Welzel, J., Metker, C., Wolff, H., and Wilhelm, K.P. (1998) SLS-irritated human skin shows no correlation between degree of proliferation and TEWL increase. Arch. Dermatol. Res. 290 615-620. 

Held, E., Lund, H., and Agner, T. Effect of different moisturizers on SLS-irritated human skin. Contact Dermatitis 2001 44 229-34. 

The SLS is frequently used to induce experimental irritant dermatitis. The reaction is characterized by erythema, increased TEWL, and scaliness. Susceptibility to SLS irritation can be used as an assay for the prevention of irritant reaction by moisturizers.23-25... 

A vast number of different protocols for the induction of SLS irritancy can be found in the literature.26 Concentrations spanning several order of magnitude have been used for single or multiple applications with exposure times ranging from minutes to days. In order to show the efficacy of moisturizers to prevent SLS irritation low concentrations should be used. With higher concentrations the individual differences between subjects tend to increase. The prevention of irritant dermatitis from a strong insult with high concentrations of SLS is probably beyond the capacity of bland moisturizers and more the domain of barrier creams. 

FIGURE 37.4 SLS irritation and moisturizer treatment, (a) No significant differences in skin color (a-values) were detectable with the Chromameter. (b) The same sites as in (a) scanned with the laser Doppler imager showed marked reduction of erythema. Volar forearms were treated with a water-in-oil emulsion twice daily for four weeks. Statistical significance was determined using the paired r-test ( p >. 05, p <. 01). 

Miscellaneous 4-week usage period Fatiguing index Pilot group Continuous exposure SLS/irritation as adjuvant... 

Toxicology Toxic by inhalation, sl. irritant avoid contact and inh. narcotic in high cones. target organ heart TSCA listed Environmental VOC Precaution Violent reaction with Al Hazardous Decomp. Prods. Heated to decomp., emits highly toxic fumes of F" and Cl"... 

Humans 10% SLS, 1% NaOH, 30% lactic acid, and undiluted toluene 4 BCs and white petrolatum Very different protective effects were detectable. All products were very effective against SLS irritation Schlater-Wigger and Eisner [75]... 

Humans SLS, anunonium hydroxide (NH4OH) and urea, Rhus Several protectants Most of them suppressed the SLS irritation and Rhus allergic reaction, failed to NH4OH and urea irritation Zhai et al. [101]... 

In addition to their regeneration effects, emollients have also been shown not only to treat but also to prevent ICD. A recently performed study showed on experimentally irritated skin both a significant preventive effect and a therapeutic effect of a moisturizer (Ramsing and Agner 1997). The product tested prevented irritant skin reaction due to SLS and it accelerated regeneration of skin barrier function of SLS-irritated skin of the hands judged by measurements of TEWL and electrical capacitance. 

Toxiedogy LD50 (oral, rat) > 12 g/kg (pract. nontoxic) sl. irritating to eyes, abraded skin... 

Charbonnier, V., Morrison, B.M., Paye, M., and Maibach, H.I. Open application assay in investigation of subclinical irritant dermatitis induced by sodium lauryl sulfate (SLS) in man advantage of squamometry. Skin Res. Technol. 4, 244-250 (1998). 

The DMSO, NaOH, and SLS are useful chemical probes because of the different properties of the substances and the different mechanisms by which they induce irritation. Due to its amphiphilic nature DMSO rapidly penetrates the SC and induces whealing and erythema. The aqueous NaOH solution dissolves the keratin layers, thereby introducing structural defects in the horny layer. The mechanism by which an aqueous solution of SLS induces irritation is still unknown, but SLS penetrates the barrier like DMSO, although much slower. Combined, tests with these and other chemical probes provide valuable information on the barrier properties of the SC. 

Applications. Sarcosinates show low irritation potential and are good foamers. Due to these properties they find applications in personal care products where synergistic effects with other surfactants may also be exploited. In combination with other anionics, sarcosinates will often detoxify the formulation and give improved foaming and skin feel. Sarcosinates are also used for their hydrotropic properties - the addition of sarcosinate to other anionics often gives a reduced Kraft point or a raised cloud point if combined with non-ionic surfactants. Lauroyl sarcosinate is used to formulate SLS-free toothpastes which are claimed to have improved taste profile. 

Misc. 9 exposure version Day 0 dry ice treatment FCA (id) day 4 Irritant dose of SLS pretreatment... 

Since irritants also influence the hydration state and the integrity of the skin, impedance spectroscopy provides a useful method for the quantification of skin irritant effects. The chief irritant studied has been sodium lauryl sulfate (SLS) [24-26]. Studies show that as the dose of SLS was increased, the amount of decrease in impedance was also increased [26]. By following the skin s impedance after the application of SLS, changes in the skin s conductivity showed up well before any visual signs of skin irritation were detectable [24]. In addition, it was demonstrated that exposure to SLS resulted in a gradual loss in the skin s barrier properties [24]. Finally, skin lotions have been shown to decrease the damage (as assessed by the degree the skin s impedance has decreased) caused to the skin by SLS. 

Hem SL, Bright DR, Banker GS, Pogue JP. Tissue irritation evaluation of potential parenteral vehicles. Drug Dev Commun 1974-75 1(5) 471-477. 

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