Release of nickel from coins and deposition onto skin from coin handling--comparing euro coins and SEK

Nickel induces inflammatory activation via NF-κB, MAPKs, IRF3 and NLRP3 inflammasome signaling pathways in macrophages

Nickel (Ni), an environmental hazard, widely causes allergic contact hypersensitivity worldwide. Despite that Ni-stimulated pro-inflammatory response is vital in allergy, the underlying molecular mechanisms remain largely unclear. Here, we demonstrated that NiCl₂ activated nuclear factor kappa B (NF-κB), mitogen-activated protein kinases (MAPKs) and interferon regulatory factor 3 (IRF3) signaling pathways in primary bone marrow-derived macrophages (BMDMs), leading to the altered transcription levels of interleukin-1β (IL-1β), -6, -8, -18, tumor necrosis factor-α (TNF-α) and interferon β (INF-β). We also found that nickel chloride (NiCl₂) activated Nod-like receptor 3 (NLRP3) inflammasome pathway, resulting in the proteolytic cleavage and release of IL-1β. NiCl₂ induced the accumulation of mitochondrial reactive oxygen species (mtROS) and the release of mitochondrial DNA (mtDNA), thus activating NLRP3 inflammasome pathway. Additionally, NiCl₂-induced apoptosis was dependent on the generation of mtROS, and caspase-1 activation might also partly contribute to the apoptotic process. Altogether, abovementioned results indicate that NiCl₂ induces inflammatory activation in BMDMs via NF-κB, MAPKs, IRF3 signaling pathways as well as NLRP3 inflammasome pathway, which provides a mechanism to improve the efficiency of treatment against Ni-induced allergic reactions.

Does clinical testing support the current guidance definition of prolonged contact for nickel allergy?

Background

The European Chemical Agency (ECHA) definition of prolonged contact was introduced in 2014 and has not been evaluated clinically.

Objectives

To assess whether nickel‐sensitized individuals react on patch testing with high nickel‐releasing metal discs for short and repetitive periods.

Materials and methods

We patch tested 45 nickel‐sensitized individuals double‐blind with 2 different types of high nickel‐releasing discs for 10, 30 and 60 minutes on 3 occasions over a period of 2 weeks, and for 1 longer period. Discs were tested for nickel release.

Results

Nickel release from both discs significantly exceeded the 0.5 μg Ni/cm²/week limit of the EU REACH nickel restriction. However, only 1 individual tested had a largely dose‐dependent allergic reaction.

Conclusions

The majority of nickel‐allergic subjects did not react to nickel discs after 2 hours or after repetitive exposures of up to 30 minutes on 3 occasions over a period of 2 weeks. The length of time needed to cause nickel allergic contact dermatitis in most nickel‐allergic individuals is longer than the ECHA guidance definition. Longer test times are needed to define the time required to cause dermatitis in most nickel‐allergic individuals. As a limitation, the test conditions did not adequately assess real‐life factors such as friction, which is relevant for some uses of nickel.

The role of nickel allergy in hand dermatitis and its impact on handling cupronickel currency coins. A comparative cohort study from Kuwait

INTRODUCTION

Contact with nickel-releasing coins as a cause of hand dermatitis has been debated.

AIM

Studying a hand dermatitis risk from handling Kuwaiti cupronickel coins among nickel-allergic and nickel non-allergic subjects.

MATERIAL AND METHODS

One hundred hand dermatitis patients (group I: nickel-allergic) and 100 matched patients (group II: nickel non-allergic) were selected from over 500 hand dermatitis cases seen between September 2014 and September 2015. Nickel released from Kuwaiti cupronickel coins immersed in a standardized artificial sweat solution was measured at 1, 24, 48, 144 and 168 h at room temperature. Subjects in both groups were exposed to nickel releasing coins. The process was repeated after 3 months using nickel coated coins as controls.

RESULTS

Nickel released from 20, 50 and 100 fils Kuwaiti cupronickel coins at 1 week was 28.64, 32.76, 35.76 μg/cm²/week, respectively. Ninety-one patients (29 males, 62 females) in group I and 87 patients (38 males, 49 females) in group II completed the study. 47.3% in group I vs. 13.8% in group II developed dermatitis on exposure to nickel releasing coins. Nickel coated coins resulted in dermatitis in 8.8% of group I vs. 5.7% in group II.

CONCLUSIONS

Nickel is released significantly from cupronickel Kuwaiti coins. Handling of coins caused dermatitis more often in patients with nickel-allergy compared to nickel non-allergic patients.

Nickel-smelting fumes increased the expression of HIF-1α through PI3K/ERK pathway in NIH/3T3 cells

OBJECTIVE

The purpose of this study was to investigate the effects of Nickel (Ni) -smelting fumes on oncogenic proteins in vivo and in vitro.

METHODS

Ni fallout beside a Ni smelting furnace in a factory was sampled to study its toxic effect. The effects of Ni-smelting fumes on the regulation of PI3K and ERK signaling pathways and the important downstream hypoxia inducible factor, HIF-1α, were studied both in NIH/3T3 cells and in the lung tissue of rats. NIH/3T3 cell transformation induced by Ni-smelting fumes was also observed.

RESULTS

Ni-smelting fumes activated PI3K, p-AKT, p70S6K1, and ERK proteins and increased HIF-1α expression in a time- and dose-dependent manner. However, activation was suppressed when NIH/3T3 cells were pretreated with PI3K/AKT or ERK inhibitors. Ni-smelting fumes caused malignant transformation of NIH/3T3 cells.

CONCLUSIONS

Ni-smelting fumes increased the expression of HIF-1α through the PI3K/ERK pathway in NIH/3T3 cells and induced malignant transformation in these cells indicating that Ni-smelting fumes may be a potential carcinogen in mammalian cells.

Nickel Release, ROS Generation and Toxicity of Ni and NiO Micro- and Nanoparticles

Occupational exposure to airborne nickel is associated with an elevated risk for respiratory tract diseases including lung cancer. Therefore, the increased production of Ni-containing nanoparticles necessitates a thorough assessment of their physical, chemical, as well as toxicological properties. The aim of this study was to investigate and compare the characteristics of nickel metal (Ni) and nickel oxide (NiO) particles with a focus on Ni release, reactive oxygen species (ROS) generation, cellular uptake, cytotoxicity and genotoxicity. Four Ni-containing particles of both nano-size (Ni-n and NiO-n) and micron-size (Ni-m1 and Ni-m2) were tested. The released amount of Ni in solution was notably higher in artificial lysosomal fluid (e.g. 80–100 wt% for metallic Ni) than in cell medium after 24h (ca. 1–3 wt% for all particles). Each of the particles was taken up by the cells within 4 h and they remained in the cells to a high extent after 24 h post-incubation. Thus, the high dissolution in ALF appeared not to reflect the particle dissolution in the cells. Ni-m1 showed the most pronounced effect on cell viability after 48 h (alamar blue assay) whereas all particles showed increased cytotoxicity in the highest doses (20–40 μg cm²) when assessed by colony forming efficiency (CFE). Interestingly an increased CFE, suggesting higher proliferation, was observed for all particles in low doses (0.1 or 1 μg cm^-2). Ni-m1 and NiO-n were the most potent in causing acellular ROS and DNA damage. However, no intracellular ROS was detected for any of the particles. Taken together, micron-sized Ni (Ni-m1) was more reactive and toxic compared to the nano-sized Ni. Furthermore, this study underlines that the low dose effect in terms of increased proliferation observed for all particles should be further investigated in future studies.

Involvement of L-type Ca²⁺ channel and toll-like receptor-4 in nickel-induced interleukin-8 gene expression

The metal nickel (Ni(2+)) is found everywhere in our daily lives, including coins, costume jewelry, and even nuts and chocolates. Nickel poisoning can cause inflammatory reactions, respiratory diseases, and allergic contact dermatitis. To clarify the mechanism by which nickel induces mediators of inflammation, we used the human acute monocytic leukemia THP-1 cell line as a model. Interleukin (IL)-8 promoter activity as well as gene expression were tested by luciferase assay and real-time polymerase chain reaction. The underlying mechanisms of nickel-induced IL-8 were investigated. We found that nickel induced IL-8 gene expression via the L-type Ca(2+) channel, Toll-like receptor-4 (TRL-4) and nuclear factor NF-κB signal transduction pathways. Nickel activated NF-κB expression through extracellular signal-regulated kinase 1/2 phosphorylation and then increased IL-8 expression. Thus, the L-type Ca(2+) channel and TRL-4 play important roles in nickel-induced inflammatory gene expressions.

"Mint" Condition: Contact Dermatitis in an Adolescent Numismatist

Allergic contact dermatitis (ACD) is common in children and adolescents. A history of persistent rash despite appropriate treatment should raise suspicion of ACD. We present the case of a 16-year-old boy with chronic dermatitis suspected of being a possible nickel allergy. He and his mother denied known common exposures. Patch testing confirmed allergies to multiple metals and several preservatives. A detailed social history revealed that the patient was an avid coin collector. Information about hobbies and activities should be elicited in any patient in whom ACD is suspected to determine exposures they may not initially have considered relevant. This case highlights the importance of pre- and posttest counseling and exposure history.

Nickel induces interleukin-1β secretion via the NLRP3-ASC-caspase-1 pathway

Exposure to nickel (Ni(2+)) can trigger allergic reactions in susceptible individuals, which is widely accepted as the major cause of allergic contact hypersensitivity (CHS) worldwide. Although Ni(2+)-induced proinflammatory responses clearly play a pivotal role in CHS, the underlying molecular mechanism has not been fully defined. Here we report that Ni(2+) activates the NLRP3-ASC-caspase-1 immune signaling pathway in antigen-presenting cells, leading to the proteolytic processing and secretion of a proinflammatory cytokine, interleukin-1β (IL-1β). The activation of this signaling axis is independent of phagolysosome-cathepsin B pathway. Instead, Ni(2+) induces mitochondrial reactive oxygen species accumulation and cation fluxes, both of which are required for activating the NLRP3-ASC-caspase-1 pathway. Together, these results identified a novel innate immune signaling pathway (NLRP3-ASC-caspase-1-IL-1β) activated by Ni(2+) and provided a mechanistic basis for optimizing the therapeutic intervention against Ni(2+)-induced allergy in patients.

Resin monomers act as adjuvants in Ni-induced allergic dermatitis in vivo

Resin monomers (RMs) are inflammatory agents and are thought to cause allergic contact dermatitis (ACD). However, mouse models are lacking, possibly because of the weak antigenicities of RMs. We previously reported that inflammatory substances can promote the allergic dermatitis (AD) induced by intradermally injected nickel (Ni-AD) in mice. Here, we examined the effects of RMs on Ni-AD. To sensitize mice to Ni, a mixture containing non-toxic concentrations of NiCl2 and an RM [either methyl methacrylate (MMA) or 2-hydroxyethyl methacrylate (HEMA)] was injected intraperitoneally or into ear-pinnae intradermally. Ten days later, a mixture containing various concentrations of NiCl2 and/or an RM was intradermally injected into ear-pinnae, and ear-swelling was measured. In adoptive transfer experiments, spleen cells from sensitized mice were transferred intravenously into non-sensitized recipients, and 24 h later NiCl2 was challenged to ear-pinnae. Whether injected intraperitoneally or intradermally, RM plus NiCl2 mixtures were effective in sensitizing mice to Ni. AD-inducing Ni concentrations were greatly reduced in the presence of MMA or HEMA (at the sensitization step from 10 mM to 5 or 50 µM, respectively, and at the elicitation step from 10 µM to 10 or 100 nM, respectively). These effects of RMs were weaker in IL-1-knockout mice and in macrophage-depleted mice. Cell-transfer experiments in IL-1-knockout mice indicated that both the sensitization and elicitation steps depended on IL-1. Challenge with an RM alone did not induce allergic ear-swelling in mice given the same RM + NiCl2 10 days before the challenge. These results suggest that RMs act as adjuvants, not as antigens, to promote Ni-AD by reducing the AD-inducing concentration of Ni, and that IL-1 and macrophages are critically important for the adjuvant effects. We speculate that what were previously thought of as "RM-ACD" might include ACD caused by antigens other than RMs that have undergone promotion by the adjuvant effects of RMs.

Cobalt skin dose resulting from short and repetitive contact with hard metals

BACKGROUND

Many daily contacts with metallic items are short and repetitive, and result in metal release; material, sweat, friction and wear may all be important.

OBJECTIVES

To study cobalt release and skin deposition as a result of many short and repetitive contacts with two cobalt-containing materials.

MATERIALS/METHODS

Study participants (n = 5) handled two types of hard metal disc (Co 6% and Co 15% Cr 0.6%) for 30 min. Deposited cobalt skin doses were measured with acid wipe sampling and chemical analysis. Cobalt release from the hard metal discs in artificial sweat was measured under conditions simulating those present during the handling of discs.

RESULTS

Average cobalt skin doses from discs containing 6% Co and 15% Co 0.6% Cr were 1.1 µg/cm(2) [standard deviation (SD) 0.4 µg/cm(2) ] and 0.7 µg/cm(2) (SD 0.5 µg/cm(2) ), respectively. More cobalt was released from hard metal discs containing 6% Co [11.4 µg/cm(2) (SD 1.2 µg/cm(2) )] than from discs containing 15% Co 0.6% Cr [4.8 µg/cm(2) (SD 0.6 µg/cm(2) )]. 10% to 15% of the potentially available cobalt was deposited on the skin during handling.

CONCLUSIONS

It is likely that the cobalt deposited as a result of short and repetitive contact with hard metals may cause harm. Research regarding cobalt exposure, metal release and the deposition of skin-sensitizing metals resulting from short and repetitive contact is needed for a better understanding of the allergy risk.

New UK nickel-plated steel coins constitute an increased allergy and eczema risk

BACKGROUND

Nickel-plated steel coins have recently been introduced in the United Kingdom.

OBJECTIVES

To compare the performance and allergy risk of the new nickel-plated coins (five and ten pence) with those of the cupro-nickel coins being replaced.

MATERIALS AND METHODS

Coin handling studies with assessment of skin exposure and metal release in artificial sweat were performed. Six volunteers participated.

RESULTS

The amount of nickel deposited onto skin during the handling of nickel-plated coins for 1 hr was 7.5 µg/cm(2) , four times higher than that from cupro-nickel coins. The nickel content in the oxidized surface of nickel-plated coins was higher, explaining the higher skin dose. Initial nickel release rates were 10-27 times higher than 1-week rates, emphasizing that brief and repeated contact results in significant nickel exposure.

CONCLUSIONS

Nickel-plated coins deposit higher levels of nickel onto skin than cupro-nickel coins, and hence pose an increased allergy risk. One-week release in artificial sweat is not suitable for determining the risk of handling items with high nickel release that come into short, repeated contact with the skin. The nickel skin dose is recommended for risk assessment. UK citizens are now, because of this change in coinage, unnecessarily exposed to higher levels of nickel on the skin. This is of public health concern.

Analysis of the toll-like receptor 2-2 (TLR2-2) and TLR4 mRNA expression in the intestinal mucosal immunity of broilers fed on diets supplemented with nickel chloride

Toll-like receptor (TLRs) are important innate immune receptors, and TLR2 and TLR4 play an important role in intestinal mucosal innate immunity. It has been found that nickel (Ni) can affect the immune system in broilers. The purpose of this study was to analyze changes in TLR2-2 and TLR4 mRNA expression levels in the intestinal mucosal immunity system of broilers induced by dietary nickel chloride (NiCl₂) using quantitative real-time polymerase chain reaction (qRT-PCR) assays. Two hundred and forty one-day-old avian broilers were divided into four groups and fed on a corn-soybean basal diet as control diet or the same basal diet supplemented with 300, 600 and 900 mg/kg of NiCl₂ for 42 days. Results showed that the TLR2-2 and TLR4 mRNA expression levels in the intestinal mucosa and the cecal tonsil were lower (p < 0.05 or p < 0.01) in the 300, 600 and 900 mg/kg groups than those in the control group. It was concluded that dietary NiCl₂ in excess of 300 mg/kg could reduce TLR2-2 and TLR4 mRNA expression levels in the intestinal mucosa and cecal tonsil in broilers, implying that the innate immunity in intestinal mucosal immune system could be impaired by pathways involving injured surface epithelium cells or/and the inhibition of the TLR signal transduction.

The cost of nickel allergy: a global investigation of coin composition and nickel and cobalt release

BACKGROUND

Nickel is widely used in coins; nickel may cause contact allergy and allergic contact dermatitis in those who handle them.

OBJECTIVES

To investigate alloy use, coin composition and nickel and cobalt release for a worldwide selection of currently circulating coins.

MATERIALS AND METHODS

Eight hundred and fifty coins of 361 different denominations or issues from 52 countries were collected and analysed with X-ray fluorescence spectrometry and nickel and cobalt spot tests.

RESULTS

Copper-nickel was the most frequently identified coin alloy, being observed in 100 denominations (28%), followed by aluminium-bronze (62, 17%). In total, 239 denominations released nickel (28%). Coins from Bolivia, Brazil and Costa Rica did not release nickel. Fewer than one-third of the denominations or issues from China, India, the euro area and Indonesia released nickel. In the United States, the Russian Federation, Japan, and Mexico, one-third or more of the denominations released nickel.

CONCLUSIONS

This worldwide selection of circulating coins covered countries with 75% of the world population, and shows that the majority of the world population lives in countries where coins release nickel. Pertinently, ∼ 40% of circulating coin denominations do not release nickel.

Metal release from stainless steel powders and massive sheets--comparison and implication for risk assessment of alloys

Industries that place metal and alloy products on the market are required to demonstrate that they are safe for all intended uses, and that any risks to humans, animals or the environment are adequately controlled. This requires reliable and robust in vitro test procedures. The aim of this study is to compare the release of alloy constituents from stainless steel powders of different grades (focus on AISI 316L) and production routes into synthetic body fluids with the release of the same metals from massive sheets in relation to material and surface characteristics. The comparison is justified by the fact that the difference between massive surfaces and powders from a metal release/dissolution and surface perspective is not clearly elucidated within current legislations. Powders and abraded and aged (24 h) massive sheets were exposed to synthetic solutions of relevance for biological settings and human exposure routes, for periods of up to one week. Concentrations of released iron, chromium, nickel, and manganese in solution were measured, and the effect of solution pH, acidity, complexation capacity, and proteins elucidated in relation to surface oxide composition and its properties. Implications for risk assessments based on in vitro metal release data from alloys are elucidated.

Nickel release and surface characteristics of fine powders of nickel metal and nickel oxide in media of relevance for inhalation and dermal contact

Differences in surface oxide characteristics and extent of nickel release have been investigated in two thoroughly characterized micron-sized (mainly <4 μm) nickel metal powders and a nickel oxide bulk powder when immersed in two different synthetic fluids, artificial sweat (ASW-pH 6.5) and artificial lysosomal fluid (ALF-pH 4.5) for time periods up to 24h. The investigation shows significantly more nickel released from the nickel metal powders (<88%) compared to the NiO powder (<0.1%), attributed to differences in surface properties. Significantly more nickel was released from the nickel metal powder with a thin surface oxide predominantly composed of non-stoichiometric nickel oxide (probably Ni(2)O(3)), compared to the release from the nickel metal powder with a thicker surface oxide predominantly composed of NiO and to a lesser extent Ni(2)O(3) (88% and 25% release after 24 h in ALF, respectively). Significantly lower amounts of nickel were released from the nickel metal powders in ASW (2.2% and <1%, respectively). The importance of particle and surface characteristics for any reliable risk assessment is discussed, and generated data compared with literature findings on bioaccessibility (released fraction) of nickel from powders of nickel metal and nickel oxide, and massive forms of nickel metal and nickel-containing alloys.

Nickel induces apoptosis in human neutrophils

Nickel is an ubiquitous transition metal that is industrially applied in many forms, which inevitably leads to a high degree of occupational and environmental exposure. Over-exposure to nickel can produce a variety of adverse effects on human health, including allergy and lung and nasal cancers. In the present study, it is demonstrated, for the first time, that nickel [(Ni(II)] (as a nickel nitrate salt) at concentrations that may be attained in vivo, induces neutrophils' apoptosis by the intrinsic pathway. The use of diphenyleneiodonium, a NADPH oxidase inhibitor, delayed Ni(II)-induced apoptosis, suggesting that NADPH oxidase-derived reactive oxygen species and subsequent signaling could contribute to this event. This is an important finding since increased apoptosis mediated by nickel may disrupt the physiological activities of neutrophils, with potential impact in its immunological and antimicrobial role.

Coin exposure may cause allergic nickel dermatitis: a review

Nickel is used in coins because the metal has beneficial properties, including price, colour, weight, and corrosion resistance, and also because it is easy to stamp. It has often been claimed that the duration of skin contact with coins is too short to cause nickel release and dermatitis. However, it is well known by dermatologists specialized in occupational skin diseases, and by their nickel-allergic patients, that hand eczema in cashiers and other professionals who handle coins may be caused or aggravated by nickel release from coins. In this review, we present evidence from past studies showing that nickel-containing coins can indeed pose a risk for those who handle them. For protection of the health of consumers, cashiers, and other workers who handle coins, it is suggested that coins without nickel release should be used as a substitute for the high nickel-releasing coins currently in widespread use. The key risk factor in this situation is the ability of metal alloys in coins to release nickel and contaminate the skin after repeated contact from coin handling.

Crucial role for human Toll-like receptor 4 in the development of contact allergy to nickel

Allergies to nickel (Ni(2+)) are the most frequent cause of contact hypersensitivity (CHS) in industrialized countries. The efficient development of CHS requires both a T lymphocyte-specific signal and a proinflammatory signal. Here we show that Ni(2+) triggered an inflammatory response by directly activating human Toll-like receptor 4 (TLR4). Ni(2+)-induced TLR4 activation was species-specific, as mouse TLR4 could not generate this response. Studies with mutant TLR4 proteins revealed that the non-conserved histidines 456 and 458 of human TLR4 are required for activation by Ni(2+) but not by the natural ligand lipopolysaccharide. Accordingly, transgenic expression of human TLR4 in TLR4-deficient mice allowed efficient sensitization to Ni(2+) and elicitation of CHS. Our data implicate site-specific human TLR4 inhibition as a potential strategy for therapeutic intervention in CHS that would not affect vital immune responses.

Skin deposition of nickel, cobalt, and chromium in production of gas turbines and space propulsion components

Skin exposure to nickel, cobalt, and chromium may cause sensitization and allergic contact dermatitis and it is known that many alloys and platings may release significant amounts of the metals upon contact with skin. Occupational exposure to these sensitizing metals has been studied in different settings with regards to airborne dust and different biological end points, but little is known about deposition on skin from airborne dust and direct contact with materials containing the metals. In this study, skin deposition was studied in 24 workers in an industry for development and manufacturing of gas turbines and space propulsion components. The workers were employed in three departments, representing different exposure scenarios: tools sharpening of hard metal items, production of space propulsion structures, and thermal application of different metal-containing powders. A novel acid wipe sampling technique was used to sample metals from specific skin surfaces on the hands and the forehead of the workers. Total amounts of nickel, cobalt, and chromium were measured by inductively coupled plasma mass spectrometry. The result showed that nickel, cobalt, and chromium could be detected on all skin surfaces sampled. The highest level of nickel was 15 microg cm(-2) h(-1), the highest for cobalt was 4.5 microg cm(-2) h(-1), and for chromium 0.6 microg cm(-2) h(-1). The three departments had different exposures regarding the metals. The highest levels of nickel on the skin of the workers were found in the thermal applications department, cobalt in the tools sharpening department, and chromium in the space propulsion components department. In conclusion, the workers' exposure to the metals was more likely to come from direct skin contact with items, rather than from airborne dust, based on the fact that the levels of metals were much higher on the fingers than on the back side of the hands and the forehead. The skin exposure levels of nickel and cobalt detected are judged capable to induce sensitization and elicit allergic contact dermatitis.