Synthetic Sweat Research Articles

Characterization of the corrosion layer of copper-nickel alloys in a synthetic sweat medium by FTMS and LAMMA laser microprobes

This study conducted with FTMS and LAMMA laser microprobes has made it possible to characterize the corrosion layer formed on the surface of copper-nickel alloys. This was done after 6 weeks of immersion in synthetic sweat. The experimental results show that the corrosion layer is essentially composed of copper-based species, the nature of which is determined by the alloy composition. We show the formation of copper trihydroxy-chloride for alloys with a high copper content as well as copper (I) oxide doped with chloride anions for alloys with a high nickel content. We also highlighted the selective corrosion of nickel. This characterization of the corrosion layer as well as the selectivity of the corrosion process permit us to explain the evolution of the quantity of nickel released, which is necessary in turn to estimate the allergenic power of these alloys during their immersion in synthetic sweat.

Permeability of protective gloves to sodium lauryl sulfate. Release chambers used as an in vitro test system.

Gloves are important and necessary in many occupations especially in wet work. They may offer a protection against harmful materials, but many substances may also penetrate protective gloves. The permeability of 6 different commonly used protective gloves to the anionic detergent sodium lauryl sulfate (SLS) was investigated. The gloves were tested as membranes in diffusion cells at 32°C. ((35) S)SLS 1% was used as permeant and synthetic sweat was used as recipient. Samples were counted on a scintillation counter. During a test period of 24 h, none of the gloves tested were found to be permeable to SLS. The gloves tested were found to offer protection against SLS. The difussion cells were useful for in vitro testing of protective gloves under controlled experimental conditions.

Deposition of corrosion-resistant chromium and nitrogen-doped chromium coatings by cathodic magnetron sputtering

This work deals with the realization of corrosion-resistant chromium-based thin films by cathodic magnetron sputtering. A systematic study of the deposition parameters (substrate temperature, pressure and gas mixture composition) has been carried out to determine the optimal conditions to obtain films with good corrosion resistance and also with good mechanical properties such as hardness, wear resistance and adhesion. The structure of the films has been determined by X-ray diffraction and their composition by X-ray photoelectron spectroscopy. The corrosion resistance of the samples has been characterized by an electrochemical method with a potentiostat and a synthetic sweat test. It is shown that the substrate temperature has a great effect on the film structure and texture. Appropriate doping with nitrogen makes it possible to increase the coating density and decrease the grain size, with a corresponding improvement in the corrosion resistance of the films. This doping also allows us to improve the microhardness up to 35 GPa.

Percutaneous absorption of inorganic lead compounds

In vivo experiments with the stable lead isotope, 204Pb, have confirmed that inorganic lead compounds can be absorbed through the skin. Three different analytical techniques — thermal ionization mass spectrometry, inductively coupled plasma mass spectrometry and anodic stripping voltammetry — showed that lead, as lead nitrate or lead acetate, was rapidly absorbed through the skin and detectable in sweat, blood and urine within 6 h of skin application. Of the 4.4 mg of lead applied to the skin in one experiment, 1.3 mg was absorbed within 24 h. Initial rapid uptake was probably via sweat glands and hair follicles, followed by slower absorption via the transepidermal route. While increases in 204Pb concentration and abundance were observed, no increase in total lead to in blood or urine was found. It is possible that the physicochemical form of skin-absorbed lead partitions strongly into extracellular fluid, but has a low affinity for erythrocytes. There was no significant difference in uptake of lead into erythrocytes (in vitro) from normal saline, synthetic sweat or sauna sweat. Ultrafiltration of sweat showed that up to 70% of lead in sweat was associated with > 30 000 MW particles. It is possible that percutaneous absorption of lead could contribute significantly to lead body burden, particularly from occupational exposure to lead in dust. Moreover, because lead absorbed through the skin was only just detectable in blood, and blood lead is the main criterion by which industry determines exposure, skin-absorbed lead may remain undetected.

Skin elicitation threshold of ethylbutyl thiourea and mercaptobenzothiazole with relative leaching from sensitizing products

We studied 3 contact sensitizers present in rubber products, ethylbutyl thiourea (EBT), 2-mercaptobenzothiazole (MBT) and 2,2-dithio-bis-benzothiazole (MBTS), to relate the amount of sensitizer eliciting allergic contact dermatitis to the quantity leaching from a product into various biological fluids: normal saline, human plasma and 3 synthetic sweat solutions of pH 5.5 to 7.5. To determine the amount of sensitizer remaining after leaching, Soxhlet extraction with acetonitrile was subsequently performed. High-performance liquid chromatography was used for chemical analysis. 12 MBT-sensitive patients were patch tested with serial dilutions of MBT and MBTS in petrolatum. A Latin Square design was used in statistical analysis of variance of the patch test results. Large amounts of thioureas leached from 2 rubber articles eliciting thiourea dermatitis, the literature suggesting that these would have been well above the elicitation threshold. Leaching of MBTS was relatively greater than MBT into most media, whereas MBT was a more potent elicitor than MBTS at equivalent concentrations. The lowest eliciting concentration of MBT in 1 subject was 0.01%. Such information should prove helpful to manufacturers in designed products that do not release allergens sufficiently to cause reactions in consumers.

Corrosion stability of nickel in Ni-alloys in synthetic sweat

Skin contact with a metallic object containing nickel is liable to provoke allergic reactions if the quantity of nickel released is higher than a threshold of 8·267·10−12 kg m−2 s−1 (0·5 μg cm−2 week−1). The release of nickel is determined by analysing the nickel in synthetic sweat in which the sample has lain for a week. The techniques used are atomic emission spectrophotometry for the analysis of the sweat and electron dispersive spectroscopy for the surface analysis. The results obtained for three different Ni-alloys enabled us to underscore the importance of the corrosion test parameter (volume of synthetic sweat per surface unit) on the quantity of nickel liberated, and thus leading us to a reflection about the mechanism of nickel dissolution within the framework of a reference test.

Release of thiurams and carbamates from rubber gloves

A method for quantitative determination of thiuram and carbamate derivatives released from rubber gloves into synthetic sweat is presented. The analysis was based upon determination of ester derivatives using gas-chromatography/mass spectrometry and isotope-dilution. The detection limit was 0.1 mg thiuram/carbamate in 200 ml synthetic sweat (0.5 ppm). The release of thiurams and carbamates from 5 household and 5 surgical types of gloves into synthetic sweat was determined. Each of the natural rubber gloves released varying amounts of thiurams (0-4.3 mg) as well as carbamates (0-8.1 mg). 22 thiuram-sensitized patients were patch tested with pieces of the gloves. Gloves releasing considerable amounts of thiurams and/or carbamates seemed to cause more positive patch test reactions in these patients than gloves releasing smaller amounts. Surgical gloves made from natural rubber caused a substantial larger number of positive patch test reactions than household gloves made from natural rubber. The amounts released per cm2 of the gloves were of the same order of magnitude as the content per cm2 patch test of thiuram mix, diluted 1:10. The accessibility of a quantitative, chemical analysis for thiurams and carbamates released from rubber gloves makes it reasonable to ask for declarations of rubber gloves. Proposals for threshold values for release of thiurams and carbamates from rubber gloves may be given in the future.

Nickel release from 304 and 316 stainless steels in synthetic sweat. Comparison with nickel and nickel-plated metals. Consequences on allergic contact dermatitis

Release of nickel from nickel or nickel-plated metals, is often responsible for allergic contact dermatitis. However, the effect of nickel-bearing stainless steels is not well known. In this paper AISI 304, 316 and 430 type stainless steels, as well as nickel and nickel-plated materials, are investigated. Three tests were carried out: electrochemical tests and leaching experiments in sodium chloride (0.05 M) and synthetic sweat solutions, and clinical patch tests on 50 patients already sensitive to nickel. Results of the leaching experiments show that nickel and nickel-plated samples release nickel in an amount much larger than 0.5 μg cm −2 week −1, in sodium chloride and synthetic sweat solutions of neutral or acidic pH (6.6 and 4.5 respectively), while AISI 304, 316L and 430 grades release nickel in very small amounts ( <0.03 μgcm −2week −1 ) in those solutions. These differences are attributed to the corrosion resistance of these stainless steels in chloride solutions, due to the protective effect of their chromium-rich passive films; for those materials, no localised corrosion is observed in the experimental solutions, even at pH 4.5, while pitting occurs on nickel and nickel-plated steel. However, complementary studies show that, for resulphurised stainless steels (for instance free-machining steels), the MnS inclusions may dissolve, mainly at acidic pH. In this case nickel release becomes larger. Thus, stainless steels AISI 304, 316 and 430, should not cause any allergic contact dermatitis. This was confirmed by the clinical patch tests which showed that 96% of the patients were intolerant to the nickel-plated samples, while low sulphur containing stainless steel samples elicited no reactions in the patients. Conversely, resulphurised stainless steel (AISI 303), led to reactions in 14% of the patients. In addition, it was shown that the dimethylglyoxime test was not relevant for selecting materials which cause no contact dermatitis. A new test was then proposed, in accordance with the present results.

Nickel dermatitis from cheap earrings.

In 1988, 64% of our patients patch test positive to at least 1 allergen of the ICDRG standard series were nickel sensitive. In 70% of 300 patients evaluated, dermatitis started on the earlobes and was related to the regular wearing of cheap earrings. At the same time, 62% of 735 young schoolgirls were found to have dermatitis of their earlobes and all regularly wore cheap earrings. 9 clasps and clips commonly used in earrings released high quantities of nickel ions (between 49 and 103 micrograms/12 h), having been stored in synthetic sweat. A round piece cut from a clasp was taped to the skin of 30 nickel-sensitive patients, previously tested with 20 microliters of NiSO4 5%, 2.5%, 1% aq. solutions, giving a response similar to that caused by the 5% solution. High daily absorption of Ni ions through the skin follows its repetitive exposure to cheap earrings, causing, firstly, a direct inflammatory reaction, then followed, in our opinion, by sensitization.

Allergic contact dermatitis to nickel: Bioavailability from consumer products and provocation threshold

Twelve subjects sensitive to nickel underwent patch testing with serial dilutions of nickel sulfate in petrolatum and in water. The provocation threshold (the lowest amount of nickel producing a reaction) varied from 5.2 mg (2.5%) to 0.47 μg (0.01%) when tested in petrolatum. The provocation threshold was higher with aqueous solutions. The lowest provocation threshold in a statistically significant number of individuals was 1,5 (μg. Nickel bioavailability from dermatitis-inducing earrings and a necklace was determined by immersing them in plasma, normal saline solution, and synthetic sweat at different pH values over 7 days. Nickel leaching under these conditions exceeded the provocation threshold 1.4- to 93-fold, depending on object and solution. The time course varied with solution. After leaching, surf ace nickel was measured by the action of dilute nitric acid and total nickel was determined by complete dissolution in aqua regia. Nickel was more bioavailable from earrings than from the necklace, presumably reflecting different metallurgy. Plasma was the most effective solution for removing available nickel from earrings, a possible explanation for the frequent induction of sensitization by ear piercing. Comparison of provocation threshold and teaching results may help determine risks from consumer products.

Patch test reactivity to nickel alloys.

11 widely used nickel alloys were investigated with respect to corrosion stability and reactivity in nickel-sensitive individuals. Alloys with a nickel release in synthetic sweat exceeding 1 microgram/cm2/week gave a strong patch test reaction in nickel-sensitive persons; those with a release below 0.5 microgram/cm2/week showed weak reactivity with one exception. Nickel allergy is a health problem. It may be minimized by using nickel alloys with a corrosion level below 0.5 microgram/cm2/week. Action should be taken by dermatologists, industry and authorities to solve this neglected problem.

Contact sensitivity to nickel in white gold.

Nickel release from white gold discs stored at room temperature for 1 week in synthetic sweat was analyzed. The nickel content of the discs was 2-15%. The nickel release from the discs was 0.09-0.82 microgram. Rhodium plating reduced the nickel release to 0.04-0.54 microgram. 18 nickel-sensitive women were patch tested with the white gold discs and all showed at least 1 positive patch test reaction. All the white gold discs gave a negative dimethylglyoxime test.

Nickel release from ear piercing kits and earrings.

Ear piercing with nickel-alloyed studs/clasps involves considerable risk of nickel sensitisation. Stainless steel studs/clasps for ear piercing and different types of earring were stored in synthetic sweat for 1 week. The nickel release was determined. One "hypoallergenic" stud/clasp released 0.005 microgram Ni; 21 unused studs/clasps and earrings released 0.05-3 microgram Ni, and 11 unused studs/clasps and earrings released 6-25 micrograms Ni. 6 earrings which caused dermatitis released 14-442 micrograms Ni. Thus, all studs/clasps and earrings released nickel. Neither gold nor silver plating prevented the nickel release. Nickel-sensitive women were asked to wear studs/clasps releasing various amounts of nickel. The most sensitive of them showed eczematous reactions to studs/clasps releasing nickel down to 0.05 micrograms. The dimethylglyoxime test was positive only when more than 10 micrograms Ni was released.

Dissolving of copper by synthetic sweat.

Dissolving of copper by synthetic sweat.

Production of a penicillin-like antibiotic by Trichophyton mentagrophytes on an agar-based medium containing skin keratin as the major nutrient.

A culture medium composed of powdered human plantar callus, synthetic sweat and agar, was used to study the synthesis of a penicillin‐like antibiotic by a strain of Trichophyton mentagrophytes grown in vitro. Series of 5 mm agar plug samples, taken radially across single colonies of the dermatophyte, were bioassayed for antibiotic, so that a profile of antibiotic concentration could be prepared. It was found that in colonies of 11 d and older, grown at 33°, antibiotic concentration was highest in the area of the colony edge.

Temperature-dependent nickel release from nickel alloys.

Nickel release from Danish one krone coins and metal buttons from jeans has been measured at 20 degrees C in distilled water and at 35 degrees C in distilled water and synthetic sweat. The temperature elevation increased the nickel release from the coins and two of the nine metal buttons investigated. Obviously the sensitivity to temperature elevation differs from one alloy to another.

A METHOD FOR THE CONTINUOUS RECORDING OF THE CONCENTRATION OF SWEAT BY MEANS OF THE ELECTRICAL CONDUCTIVITY.

A method is described to measure the total osmolar concentration of sweat by means of measuring the electrical conductivity. The method allows a continuous recording, so that the error, introduced by sampling the sweat, will be reduced. For calculations of the total osmolar concentration we have made the assumption that all the solute in sweat was NaCl. Experiments with a synthetic sweat proved the validity of this assumption, the error is about 5%.