In vitro percutaneous penetration and characterization of silver from silver-containing textiles.

The objective of this study was to determine the in vitro percutaneous penetration of silver and characterize the silver species released from textiles in different layers of full thickness human skin. For this purpose, two different wound dressings and a garment soaked in artificial sweat were placed in the donor compartments of Franz cells for 24 hours. The concentration of silver in the donor phase and in the skin was determined by an electrothermal atomic absorption spectrometer (ET-AAS) and by inductively coupled plasma mass spectrometer (ICP-MS). The characterization of silver species in the textiles and in the skin layers was made by scanning electron microscopy with integrated energy dispersive X-ray spectroscopy (SEM-EDX). Additionally, the size distribution of silver nanoparticles in the textiles was performed by atomic force microscopy (AFM). On the surface of all investigated materials, silver nanoparticles of different size and morphology were found. Released silver concentrations in the soaking solutions (ie, exposure concentration) ranged from 0.7 to 4.7 µg/mL (0.6-4.0 µg/cm(2)), fitting the bactericidal range. Silver and silver chloride aggregates at sizes of up to 1 µm were identified both in the epidermis and dermis. The large size of these particles suggests that the aggregation occurred in the skin. The formation of these aggregates likely slowed down the systemic absorption of silver. Conversely, these aggregates may form a reservoir enabling prolonged release of silver ions, which might lead to local effects.

Current patch test results with the European baseline series and extensions to it from the 'European Surveillance System on Contact Allergy' network, 2007-2008.

BACKGROUND: The pattern of contact sensitization to the supposedly most important allergens assembled in the baseline series differs between countries, presumably at least partly because of exposure differences. Objectives. To describe the prevalence of contact sensitization to allergens tested in consecutive patients in the years 2007 and 2008, and to discuss possible differences. METHODS: Data from the 39 departments in 11 European countries comprising the European Surveillance System on Contact Allergy network (www.essca-dc.org) in this period have been pooled and analysed according to common standards. RESULTS: Patch test results with the European baseline series, and country-specific or department-specific additions to it, obtained in 25 181 patients, showed marked international variation. Metals and fragrances are still the most frequent allergens across Europe. Some allergens tested nationally may be useful future additions to the European baseline series, for example methylisothiazolinone, whereas a few long-term components of the European baseline series, namely primin and clioquinol, no longer warrant routine testing. CONCLUSIONS: The present analysis points to 'excess' prevalences of specific contact sensitization in some countries, although interpretation must be cautious if only few, and possibly specialized, centres are representing one country. A comparison as presented may help to target in-depth research into possible causes of 'excess' exposure, and/or consideration of methodological issues, including modifications to the baseline series.

Silver nanoparticles exert a long-lasting antiproliferative effect on human keratinocyte HaCaT cell line.

For their antibacterial activity, silver nanoparticles (Ag NPs) are largely used in various commercially available products designed to come in direct contact with the skin. In this study we investigated the effects of Ag NPs on skin using the human-derived keratinocyte HaCaT cell line model. Ag NPs caused a concentration- and time-dependent decrease of cell viability, with IC(50) values of 6.8 ± 1.3 µM (MTT assay) and 12 ± 1.2 µM (SRB assay) after 7 days of contact. A 24h treatment, followed by a 6 day recovery period in Ag NPs-free medium, reduced cell viability with almost the same potency (IC(50)s of 15.3 ± 4.6 and 35 ± 20 µM, MTT and SRB assays, respectively). Under these conditions, no evidence of induction of necrotic events (propidium iodide assay) was found. Apocynin, NADPH-oxidase inhibitor, or N(G)-monomethyl-L-argynine, nitric oxide synthase inhibitor, did not prevent NPs-induced reduction of cell viability. TEM analysis of cells exposed to NPs for 24h revealed alteration of nuclear morphology but only a marginal presence of individual NPs inside the cells. These results demonstrate that on HaCaT keratinocytes a relatively short time of contact with Ag NPs causes a long-lasting inhibition of cell growth, not associated with consistent Ag NPs internalization.

Gene expression changes in peripheral blood mononuclear cells in occupational exposure to nickel.

Allergic contact dermatitis is preceded by a clinically silent phase of sensitisation. In this study, we investigated whether the expression levels of six genes were related to nickel exposure and/or nickel sensitisation, and whether they could predict allergic manifestations to nickel. The mRNA expression level of six genes involved in cell growth (PIM1 and ETS2), metabolism/synthesis (HSD11B1 and PRDX4), apoptosis (CASP8) and signal transduction (CISH) was investigated by means of quantitative real-time RT-PCR in a cohort of 110 subjects, including healthy controls (n=51), nickel-exposed workers (n=23) and patients allergic to nickel (n=36). Our findings show that the expression levels of the analysed genes did not differ between allergic patients and healthy controls, while higher expression levels of ETS2 and CASP8 were detected in the nickel-exposed workers. Changes in ETS2 and CASP8 expression are likely to be related to nickel exposure rather than to allergy.

Nanoparticle dermal absorption and toxicity: a review of the literature.

INTRODUCTION: Nanotechnologies are among the fastest growing areas of scientific research and have important applications in a wide variety of fields. The data suggest that in the future workers and consumers exposed to nanoparticles will significantly increase. DERMAL ABSORPTION AND TOXICITY OF NANOPARTICLES: At now there are gaps in understanding about the human and environmental risk that manufactured nanoparticles pose for occupational exposed people and for consumers. There is a need for assessing the health and environmental impacts, the nanoparticles life cycle, the human exposure routes, the behavior of nanoparticles in the body, and the risk for workers. Possible routes of entry into the body include inhalation, absorption through the skin or digestive tract, injection, and absorption or implantation for drugs delivery systems. In particular, dermal absorption and skin penetration of nanoparticles needs a better evaluation because few and contradictory data are present in the literature, mainly on titanium dioxide. CONCLUSIONS: There are limited data on carbon-based nanoparticles and very few data on other metal nanoparticles increasingly used in industry. The article reviews the literature on the percutaneous absorption of nanoparticles and their effect on skin.

Human skin penetration of silver nanoparticles through intact and damaged skin.

There is a growing interest on nanoparticle safety for topical use. The benefits of nanoparticles have been shown in several scientific fields, but little is known about their potential to penetrate the skin. This study aims at evaluating in vitro skin penetration of silver nanoparticles. Experiments were performed using the Franz diffusion cell method with intact and damaged human skin. Physiological solution was used as receiving phase and 70 microg/cm2 of silver nanoparticles coated with polyvinylpirrolidone dispersed in synthetic sweat were applied as donor phase to the outer surface of the skin for 24h. The receptor fluid measurements were performed by electro thermal atomic absorption spectroscopy (ETAAS). Human skin penetration was also determined by using transmission electron microscope (TEM) to verify the location of silver nanoparticles in exposed membranes. Median silver concentrations of 0.46 ng cm(-2) (range

[Consensus Document. Update on latex exposure and use of gloves in Italian health care settings]. / Documento di Consenso. Aggiornamenti in tema di esposizione a latice e impiego di guanti in ambito sanitario.

This consensus document was prepared by an Italian working group including occupational health professionals involved for many years in the management of glove- and latex-related problems in health care settings. The aim of this document was to address the most significant technical, epidemiological, clinical, environmental and prevention problems related to the use of gloves and latex. The group's recommendations are based on scientific evidence and practical experience but they cannot be considered as final. These topics need to be periodically revised. The following points should be taken into account: glove quality seems to have improved considerably but the information on glove features provided by the manufacturers is often still inaccurate or incomplete; the regulations in force provide that the manufacturers perform tests to supply evidence for the quality of the products but they do not indicate which analytical method should be used and they do not require that the results be reported in the technical data sheets. Thus the manufacturers have only to declare that their products are "in accordance with the rules"; therefore, purchasers should require the manufacturing companies to supply detailed information and verify their reliability. Moreover, the rules should be adapted to higher quality standards; occupational physicians must be involved for the correct choice and purchase of protective gloves; the use of gloves (in particular latex gloves) and latex devices in health care settings should be based on specific criteria: procedures must be available stating which kind of gloves are suitable for specific tasks. When exposure to latex cannot be avoided it is necessary to choose products that have good biocompatibility (e.g., powder free-gloves with low allergen content); once and for all latex powdered gloves should no longer be commercially available! labels for latex devices (including gloves) should report the extractable latex allergen content. Limit values for extractable latex allergens should be established; the use of synthetic rubber gloves should be encouraged since some materials (e.g., neoprene and nitrile rubber) appear to have physical properties and protective efficacy similar to latex, plus good biocompatibility; more studies should be promoted to verify the protective efficacy of new synthetic materials; health care workers should be informed about the advisability and usefulness of using materials other than latex; health care services should not cause additional risks but rather highlight the advantages for workers and patients if the use of latex gloves and devices is minimized.

In vitro percutaneous absorption of metal compounds.

It is well known that contact with metals can be responsible for allergic contact dermatitis; also, there is experimental evidence that nickel ions are readily available on the surface of used coins containing nickel and copper. The aim of this study was to prove that metal powders of nickel (Ni), cobalt (Co) and chromium (Cr) dispersed in synthetic sweat are oxidised into respective ions that can permeate the skin. Suspensions of 5 g of metal powder (Ni, Co and Cr) in 100 mL of synthetic sweat at pH 6.5 were prepared and shaken with a stirring plate at room temperature for 30 min. Human skin membranes were set up in Franz-diffusion cells and 2 mL of the freshly made suspension were applied to the outer surface of the skin for 24h. The appearance of metal ions in the aqueous receptor phase (NaCl 0.9%) was quantified by Electro Thermal Atomic Absorption Spectroscopy (ETAAS). Also, metals ions were analysed using Differential Pulse Polarography (DDP), Differential Pulse Voltammetry (DPV) and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) techniques both in the receiving phase and in the donor solution to evaluate the presence of different ionic metallic species. DPP and DPV measurements of cobalt and nickel suspensions confirmed the presence of Co2+ and Ni2+ ions in concentration, respectively of 33.3+/-3.2 and 27.1+/-3.2 mg L(-1). Chromium ions concentration below 0.1 mg L(-1) were found in chromium suspensions bearing evidence of synthetic sweat inefficacy of oxidising chromium metal powder. Cobalt and nickel skin permeation was demonstrated in in vitro experiments using the Franz cell system giving a permeation flux of 0.0123+/-0.0054 microg cm(-2) h(-1) for cobalt and of 0.0165+/-0.00036 microg cm(-2) h(-1) for nickel and a lag time of 1.55+/-0.71 h for cobalt and of 14.56+/-0.56 for nickel. Chromium below 0.1 microg L(-1) was found in the receiving solutions. Our experiments demonstrated that metallic nickel and cobalt can be oxidised when suspended in synthetic sweat, while chromium would probably need stronger oxidising conditions. Metallic ions can permeate the skin and the Franz cell system showed that it is possible to measure a flux of ions through the skin for cobalt and nickel but not for chromium.

Allergic contact sensitivity in elderly patients.

BACKGROUND AND AIMS: Aging has been shown to be correlated with the rate and type of contact sensitization, but only a few studies have evaluated patch test reactivity in elderly subjects with an adequately large population. METHODS: The response patterns to patch testing in 1444 elderly subjects (>65 years) with suspected allergic contact dermatitis were studied, and the results compared with a control group of individuals with suspected allergic contact dermatitis, aged between 20 and 40 years. RESULTS: The prevalence of the positive patch test to at least one hapten was significantly lower in the group of elderly patients compared with adult patients (40.7 vs 47.8%, p<0.0001). However, some allergens, i.e., primin, diaminodiphenylmethane, neomycin, lanolin alcohols, paraben mix, Euxyl K400 and quinoline mix, showed an increased sensitization rate in elderly patients compared with adult patients. These allergens are now less frequently employed in the workplace, or are substances particularly used in the formulation of topical treatment of age-related diseases, i.e., leg ulcer and xerosis. It was also found that the intensity of positive patch test reactions was significantly lower in elderly patients compared with younger subjects, with higher proportions of weak (+) positive reactions. Moreover, elderly patients showed a dynamic pattern of increasing intensity of patch test reactions at the second reading after 3 days compared with the first reading after 2 days more frequently than younger patients (60 vs 53%, p<0.0001). CONCLUSIONS: These findings suggest an age-dependent decline of overall positive patch test reactions, but a higher sensitization rate to some allergens frequently used in the composition of topical treatments. The development of an allergic response in elderly patients was found to be delayed, and this may require an additional reading after 7 days and the interpretation of even weak reactions as valid positive patch test reactions.