Deposition of nickel, chromium, and cobalt on the skin in some occupations – assessment by acid wipe sampling

Retention of nickel, cobalt and chromium in skin at conditions mimicking intense hand hygiene practices using water, soap, and hand-disinfectant in vitro

BACKGROUND

During the COVID-19 pandemic, increased hand hygiene practices using water, soap and hand disinfectants, became prevalent, particularly among frontline workers. This study investigates the impact of these practices on the skin's ability to retain the allergenic metals nickel, cobalt, and chromium. The study constitutes three parts: (I) creating an impaired skin barrier, (II) exposing treated and untreated skin to nickel alone, and (III) in co-exposure with cobalt and chromium.

METHODS

Using full-thickness skin from stillborn piglets, in vitro experiments were conducted to assess retention of metals in skin at conditions mimicking intense hand hygiene practices. Treatment of skin with varying concentrations of sodium lauryl sulphate (SLS), to impair its barrier integrity was assessed. This was followed by exposure of treated and untreated skin to the metals, that were dissolved in Milli-Q water, 0.5% SLS, and ethanol respectively.

RESULTS

Results showed that pre-treatment with 5% SLS impaired the skin barrier with regards to the measure of trans epidermal water loss (TEWL). Metal amounts retained in the skin were generally higher in treated than untreated skin. The highest amounts of metal retained in skin were observed for exposure to nickel in ethanol. Co-exposure to nickel, cobalt, and chromium in 0.5% SLS resulted in the highest amounts of total metal retention.

CONCLUSIONS

The in vitro findings highlight the increased risk of metal retention in skin due to an impaired barrier. The SLS concentration used in the current study corresponds to those used in many hand hygiene products. Hence, occupational settings with frequent exposure to water, soap and disinfectants need to consider protective measures not only for the irritant exposures themselves but also simultaneous exposure to allergenic metals.

Skin and respiratory exposure to soluble lead, cobalt, nickel, copper, arsenic and silver at two South African precious metals refineries

OBJECTIVES

Precious metals refinery workers are exposed to soluble platinum group metals (PGMs) during PGM-refining but may also be exposed to hazardous non-PGMs (Pb, Co, Ni, Cu, As and Ag) still present in the matte following base metals refining. The aim of this article was to report the skin and respiratory exposure of workers to soluble non-PGMs during PGM-refining.

METHODS

Skin and respiratory exposure (of 40 workers at two precious metals refineries) were measured simultaneously over two consecutive shifts. Skin exposure was measured on the palm, wrist, neck and forehead using Ghostwipes™ and respiratory exposure was measured using the MDHS method 46/2 during which soluble metals were extracted using 0.07 M HCl and mechanical agitation, followed by ICP-MS analysis.

RESULTS

The geometric means (GM) of average skin exposure to individual soluble metals on all anatomical areas was found in the order Cu (0.018 µg/cm²) > Ni (0.016 µg/cm²) > Pb (0.008 µg/cm²) > Ag (0.006 µg/cm²) > As (0.004 µg/cm²) > Co (0.0008 µg/cm²) with the palm being the highest exposed anatomical area. The order of the GM respiratory exposure was Pb (0.224 µg/m³) > Ag (0.201 µg/m³) > Cu (0.159 µg/m³) > As (0.079 µg/m³) > Ni (0.034 µg/m³) > Co (0.016 µg/m³) with exposure to As exceeding the South African occupational exposure limit (20 µg/m³) during concentrate handling (max 66.174 µg/m³).

CONCLUSIONS

Workers were exposed to a mixture of toxic PGM and non-PGMs via the skin and inhalation. Exposure to these metals could lead to the development of diseases, such as contact dermatitis, occupational allergy, or occupational cancer. Non-PGMs must be included in hazardous chemical risk assessments and control strategies implemented at precious metals refineries.

Nickel penetration into stratum corneum in FLG null carriers - a human experimental study

Background

The filaggrin gene (FLG) plays a role in skin diseases, with the skin barrier function being impaired in FLG null carriers. The role of FLG status in relation to nickel penetration into the skin remains unclear.

Objectives

To elucidate the association between FLG status and nickel penetration into stratum corneum (SC) in individuals without self‐reported history of nickel allergy.

Methods

Forty participants (23 FLG wt and 17 FLG null) were exposed to a nickel solution (80 μg/cm²) which was applied onto 2 × 2 cm on their left forearm. After 4 h, the area was tape‐stripped with 10 consecutive tapes. Nickel in each tape was quantified using inductively coupled plasma mass spectrometry.

Results

The average recovered nickel dose was 35%–48%. A tendency towards lower recovery was seen in FLG null carriers compared to FLG wt carriers, and lower recovery in those with history of skin and/or respiratory symptoms compared to those without such history. This was however not statistically significant.

Conclusion

FLG null carriers had less nickel recovered by tape strips compared with FLG wt carriers and, compared with individuals without a history of skin and/or respiratory symptoms, indicating higher nickel penetration into SC for FLG null carriers, but further studies are needed.

GuLF DREAM: A Model to Estimate Dermal Exposure Among Oil Spill Response and Clean-up Workers

Tens of thousands of individuals performed oil spill response and clean-up (OSRC) activities following the 'Deepwater Horizon' oil drilling rig explosion in 2010. Many were exposed to oil residues and dispersants. The US National Institute of Environmental Health Sciences assembled a cohort of nearly 33 000 workers to investigate potential adverse health effects of oil spill exposures. Estimates of dermal and inhalation exposure are required for those individuals. Ambient breathing-zone measurements taken at the time of the spill were used to estimate inhalation exposures for participants in the GuLF STUDY (Gulf Long-term Follow-up Study), but no dermal measurements were collected. Consequently, a modelling approach was used to estimate dermal exposures. We sought to modify DREAM (DeRmal Exposure Assessment Method) to optimize the model for assessing exposure to various oil spill-related substances and to incorporate advances in dermal exposure research. Each DREAM parameter was reviewed in the context of literature published since 2000 and modified where appropriate. To reflect the environment in which the OSRC work took place, the model treatment of evaporation was expanded to include vapour pressure and wind speed, and the effect of seawater on exposure was added. The modified model is called GuLF DREAM and exposure is estimated in GuLF DREAM units (GDU). An external validation to assess the performance of the model for oils, tars, and fuels was conducted using available published dermal wipe measurements of heavy fuel oil (HFO) and dermal hand wash measurements of asphalt. Overall, measured exposures had moderate correlations with GDU estimates (r = 0.59) with specific correlations of -0.48 for HFO and 0.68 for asphalt. The GuLF DREAM model described in this article has been used to generate dermal exposure estimates for the GuLF STUDY. Many of the updates made were generic, so the updated model may be useful for other dermal exposure scenarios.

Influence of repeated contacts on the transfer of elemental metallic lead between compartments in an integrated conceptual model for dermal exposure assessment

Transfer of contaminants to and from the skin surface has been postulated to occur through a number of different pathways and compartments including: object(s)-to-skin, skin-to-skin, skin-to-clothing, skin-to-gloves, air-to-skin, skin-to-lips, and skin-to-saliva. However, many identified transfer pathways have been only minimally examined to determine the potential for measurable transfer. The purpose of this study was to quantitatively evaluate repeated transfer between different compartments using elemental metallic lead (Pb) in the solid form using a series of systematic measurements in human subjects. The results demonstrated that some transfer pathways and compartments are significantly more important than others. Transfer of Pb could not be measured from skin to cotton clothing or skin to laminate countertop surfaces. However, transfer was consistently measured for skin-to-skin and between the skin and the surface of nitrile gloves, suggesting the potential for significant transfer to or from these compartments in real-world exposure scenarios, and the importance of these pathways. With repeated contacts, transfer increased non-linearly between 1 and 5 contacts, but appeared to approach a steady state distribution among the compartments within 10 contacts. Consistent with other studies, relative to 100% transfer for a single contact, the quantitative transfer efficiency decreased with repeated contacts to 29% after 5 contacts and 11-12% after 10 contacts; for skin-to-skin transfer measurements, transfer efficiency after either 5 or 10 contacts was approximately 50% of the single contact transfer. These data are likely to be useful for refining current approaches to modeling of repeated contacts for dermal exposure and risk assessment.

Combined Metallomics/Transcriptomics Profiling Reveals a Major Role for Metals in Wound Repair

Endogenous metals are required for all life, orchestrating the action of diverse cellular processes that are crucial for tissue function. The dynamic wound healing response is underpinned by a plethora of such cellular behaviours, occurring in a time-dependent manner. However, the importance of endogenous metals for cutaneous repair remains largely unexplored. Here we combine ICP-MS with tissue-level RNA-sequencing to reveal profound changes in a number of metals, and corresponding metal-regulated genes, across temporal healing in mice. Wound calcium, magnesium, iron, copper and manganese are elevated at 7 days post-wounding, while magnesium, iron, aluminium, manganese and cobalt increase at 14 days post-wounding. At the level of transcription, wound-induced pathways are independently highly enriched for metal-regulated genes, and vice versa. Moreover, specific metals are linked to distinct wound-induced biological processes and converge on key transcriptional regulators in mice and humans. Finally, we reveal a potential role for one newly identified transcriptional regulator, TNF, in calcium-induced epidermal differentiation. Together, these data highlight potential new and diverse roles for metals in cutaneous wound repair, paving the way for further studies to elucidate the contribution of metals to cellular processes in the repair of skin and other tissues.

Identifying dust as the dominant source of exposure to heavy metals for residents around battery factories in the Battery Industrial Capital of China

Heavy metals (HMs) are constantly released into the environment during the production and use of batteries. Battery manufacturing has been ongoing for over six decades in the "Battery Industrial Capital" (located in Xinxiang City) of China, but the potential exposure pathways of residents in this region to HMs remain unclear. To clarify the exposure pathways and health risk of human exposure to HMs, hand wipe samples (n=82) and fingernail samples (n=36) were collected from residents (including young children (0-6 years old), children (7-12 years old) and adults (30-60 years old)) living around battery factories. The total concentrations of the target HMs (Zn, Mn, Cu, Pb, Ni, Cr, Cd, Co) in hand wipes ranged from 133 to 8040 μg/m², and those in fingernails ranged from 9.7-566 μg/g. HM levels in the hand wipe and fingernail samples both decreased with age, and higher HM levels were observed for males than females. The HM composition profiles in these two matrices represented a high degree of similarity, with Zn as the predominant element, and thus, oral ingestion and dermal exposure via dust were expected to be the most important HM exposure pathways for residents in this region. The non-carcinogenic risks (HQs) from dermal and oral ingestion exposure to Cd, Cr, and Pb were higher than those of the other five elements for all three populations, and the HQ_derm of Cd for young children was 2.1 (HQ_oral=0.6). Moreover, the hazard index (HI) values of ∑₈HMs for young children (HI_total=5.2, HI_oral=2.0, HI_dermal=3.2) and children (HI_total=1.6, HI_oral=1.3, HI_dermal=0.3) exceeded the safe threshold (1.0). Therefore, young children and children should be prioritized for protection from HM pollution, and more attention should be paid to young children's dermal exposure to Cd in this region.

Occupational exposure to nickel, cobalt, and chromium in the Lithuanian hard metal industry

BACKGROUND

Metalworkers are said to have heavy exposure to metals, but the amount of released metal ions from alloys and deposition on the hands is unknown.

OBJECTIVE

To analyze nickel, cobalt, and chromium in vitro release to the artificial sweat from nails and wire made of different alloys, and to test metal deposition on the fingers of metalworkers.

MATERIAL AND METHODS

Six different samples of nails and wire were kept in artificial sweat for 24 hours and one week, respectively. The metal release was determined by atomic absorption spectrometry (AAS). Eighty-eight consecutive metal plant workers immersed their index fingers and thumbs in separate laboratory tubes filled with deionized water for 2 minutes. The sample analysis for metals was carried out with an inductively coupled plasma mass spectrometer (ICP-MS).

RESULTS

The average released concentration of Ni was 0.0012 μg/cm² , for Co it was 0.0007 μg/cm² , and for Cr 0.0037 μg/cm² after 24 hours and 0.0135, 0.0029, and 0.0042 μg/cm² , respectively, after 1 week. There was a statistically significant increase in released concentration of Ni during one week: 0.0012 μg/cm² vs 0.0135 μg/cm² (P = .04). Medians of the detected Co amount on fingers reflected a statistically significant difference between workplaces: 0.004 μg/cm² for metalworkers vs 0.001 μg/cm² for office staff (P = .04).

CONCLUSION

Nickel (Ni), cobalt (Co), and chromium (Cr) can be released in different concentrations from nails and wire. Detected Ni and Cr levels can elicit dermatitis in already sensitized patients. Co can be extracted from alloys even if not mentioned on material safety data sheets. The finger immersion technique was used for cobalt and chromium detection on fingers for the first time.

A Case Study of Brass Foundry Workers' Estimated Lead (Pb) Body Burden from Different Exposure Routes

Objectives

The most pronounced occupational exposure routes for lead (Pb) are inhalation and gastrointestinal uptake mainly through hand-to-mouth behaviour. Skin absorption has been demonstrated for organic Pb compounds, but less is known about inorganic Pb species. Several legislative bodies in Europe are currently proposing lowering biological exposure limit values and air exposure limits due to new evidence on cardiovascular effects at very low blood Pb levels. In light of this, all exposure routes in occupational settings should be revisited to evaluate how to lower the overall exposure to Pb.

Methods

The aim of the study was to investigate the possible exposure routes in workers operating computer numerical control-machines in a brass foundry and specifically to understand if metal cutting fluids (MCFs) used by the workers could lead to skin absorption of Pb. The different bronze alloys at the facility may contain up to 20% Pb. After obtaining written informed consent from the workers (n = 7), blood, skin wipes, and personal air samples were collected. In addition, MCFs used on the day of exposure measurements were collected for in vitro skin absorption studies using stillborn piglet skin mounted in static Franz diffusion cells (n = 48). All samples were analysed for Pb content using inductively coupled plasma mass spectrometry.

Results

Pb air concentration (<0.1–3.4 µg m⁻³) was well below the Swedish occupational exposure limit value. Blood Pb was in the range of <0.72–33 µg dl⁻¹, and Pb on skin surfaces, after performing normal work tasks during 2 h, was in the range of 0.2–48 µg cm⁻². Using the MCFs in diffusion cells showed that skin absorption had occurred at very low doses, and that up to 10% of the Pb content was present in the skin after 24 h exposure. Using these results in the US EPA adult lead model, we could estimate a contribution to blood Pb from the three exposure routes; where hand-to-mouth behaviour yielded the highest contribution (16 µg Pb dl⁻¹ blood), followed by skin absorption (3.3–6.3 µg Pb dl⁻¹ blood) and inhalation (2.0 µg Pb dl⁻¹ blood).

Conclusions

This case study shows that MCF may lead to skin absorption of inorganic Pb and contribute to a systemic dose (quasi-steady state). Furthermore, even though good hand hygienic measures were in place, the workers’ skin exposure to Pb is in all likelihood an important contributor in elevating blood Pb levels. Skin exposure should thus be monitored routinely in workers at facilities handling Pb, to help reducing unnecessary occupational exposure.

Occupationally Related Nickel Reactions: A Retrospective Analysis of the North American Contact Dermatitis Group Data 1998-2016

BACKGROUND

The epidemiology of nickel allergy in occupational settings is not well understood.

OBJECTIVE

The aim of the study was to characterize occupationally related nickel allergy (ORNA).

METHODS

This is a retrospective cross-sectional analysis of 44,378 patients patch tested by the North American Contact Dermatitis Group from 1998 to 2016. Characteristics of individuals with ORNA were compared with those with non-ORNA (NORNA).

RESULTS

A total of 7928 (18.2%) individuals were positive to nickel sulfate 2.5%. Two hundred sixty-eight (3.4%) had ORNA. As compared with NORNA, ORNA was statistically associated with the male sex (41.0% vs 12.9%, P < 0.001), a diagnosis of irritant contact dermatitis (22.4% vs 12.0%, P < 0.001), and no history of eczema (81.7% vs 75.7%, P = 0.0217). The most common sites of ORNA dermatitis were hand (39.9%) and arm (18.1%), which were significantly more common than in NORNA (P < 0.0001). Sixteen industry categories and 22 occupation categories were identified for ORNA; the most common industries were durable goods manufacturing (24.6%) and personal services (15.7%), and the most frequent occupations were hairdressers/cosmetologists/barbers (14.3%), machine operators (9.3%), and health care workers (7.1%). Overall 30% of ORNA occupations were in metalworking. Of 215 ORNA sources identified, instruments/phones/other equipment (16.3%), vehicles/machinery (15.8%), and tools (15.3%) were the most common.

CONCLUSIONS

Occupational nickel allergy is distinct from nonoccupational nickel allergy.

Ultraclean paired sampling for metal analysis in neurodegenerative disorders

The causes of neurodegenerative disorders are largely unknown. Environmental factors seem to contribute to neurodegeneration in genetically susceptible individuals. Increasing evidence point towards a key role for environmental exposure in the causation of neurodegenerative disorders and specifically for metal exposure. Alterations of metalloproteins seem to be a common motif in neurodegeneration and enough evidence has now accumulated to designate these disorders as metallopathies. Paired sampling refers to the simultaneous sampling of CSF and blood and by comparing metal concentrations between CSF and blood conclusions about exposure and barrier properties can be drawn. However previous reports on metal concentrations in body fluids in neurodegenerative disorders show a wide variation in results hampering firm conclusions on the role of metals in degeneration of nerve cells. Here we suggest some steps and measures to minimise this variation, most important sampling performed in a cleanroom with filtered air and the use of acid washed perfluoroalkoxy vials. By strict adherence to ultraclean paired sampling technique conclusive results concerning the role of metals in neurodegenerative disorders can be generated.

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.

Contamination of skin and surfaces by cobalt in the hard metal industry

BACKGROUND

It is well known that hard metal workers have historically been affected by contact allergy to cobalt. Knowledge is sparse about occupational skin exposure to cobalt, in terms of skin doses and sources of exposure, which could be used to improve protection of workers.

OBJECTIVES

To improve knowledge about skin doses and sources of skin exposure to cobalt within hard metal production, thereby facilitating better protection of workers.

METHODS

Forty workers were sampled on the index finger by acid wipe sampling after 2 hours of work. The samples were analysed with inductively coupled plasma mass spectrometry. Cobalt spot testing was performed in the work environment.

RESULTS

The highest skin doses were found among raw material workers. Skin doses among other production workers were also significant. Most office workers had low, but measurable, levels of cobalt on the skin. Glove use varied between workers. Cobalt was found on production equipment, on items in the canteen area, and on handles and buttons throughout the company.

CONCLUSIONS

Cobalt skin doses were prominent, and originated from contact with raw materials, sintered materials, and contaminated surfaces. Cobalt was present on surfaces outside production areas. Companies need to identify and reduce skin exposure for protection of workers.

Biological monitoring of dermal and air exposure to cobalt at a Swedish hard metal production plant: does dermal exposure contribute to uptake?

BACKGROUND

Occupational exposure to cobalt is well established in hard metal manufacture. Cobalt is known to cause contact allergy, asthma, hard metal lung disease, and lung cancer. The relationship between skin exposure and uptake determined in blood has not been extensively investigated.

OBJECTIVE

To examine whether skin and inhalable air exposure to cobalt contributes to uptake, determined as cobalt in blood, in a hard metal manufacturing factory.

METHODS

The amount of cobalt on the skin found with an acid wash technique, the air concentrations of inhalable cobalt and cobalt blood concentrations were determined and correlated in exposed workers.

RESULTS

We found a significant rank correlation for cobalt concentrations on the skin, in inhalable air, and in blood (0.376-0.498). Multiple linear regression showed significant regression coefficients for cobalt skin exposure and blood (B = 0.01, p < 0.05) and for inhalable cobalt in air and blood (B = 49.1, p < 0.001). According to our model based on data from the regression analyses, a twofold increase in skin exposure levels at different air concentrations caused a 3-14% increase in blood levels.

CONCLUSIONS

Our data suggest that skin exposure to cobalt in the hard metal industry could affect the total uptake at the same order of magnitude as air exposure.

Snapshot of cobalt, chromium and nickel exposure in dental technicians

BACKGROUND

It is not fully understood where and how people are exposed to sensitizing metals. Much can be learnt from studying occupational settings where metals are handled.

OBJECTIVES

To quantify cobalt (Co), chromium (Cr) and nickel (Ni) exposure on the skin and in the air, and urine levels, in dental technicians working with tools and alloys that may result in skin and respiratory exposure.

METHODS

The metal skin dose was quantified with acid wipe sampling in dental technicians (n = 13). Air exposure was monitored by personal air sampling. Spot urine samples were collected for 24 h. Metals were analysed with inductively coupled plasma mass spectrometry.

RESULTS

Before work, Co was detected on the skin of 10 participants (0.00025-0.0039 µg/cm² ), and Cr (0.00051-0.011 µg/cm² ) and Ni (0.0062-0.15 µg/cm² ) on the skin of all participants. After a 2-h period without hand washing, CoCr-exposed participants had more Co on the skin (p = 0.004) than non-CoCr-exposed participants. Co was found in 10 air samples (0.22-155 µg/m³ ), Cr in nine (0.43-71 µg/m³ ), and Ni in four (0.48-3.7 µg/m³ ). Metal urine concentrations were considered to be normal.

CONCLUSIONS

Dental technicians were exposed to Co, Cr and Ni on the skin and through the air, which was not reflected in the urine concentrations in this study. Cobalt skin doses may potentially elicit allergic contact dermatitis and cause sensitization.

Contact dermatitis: a practice parameter-update 2015

This parameter was developed by the Joint Task Force on Practice Parameters, which represents the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma & Immunology. The AAAAI and the ACAAI have jointly accepted responsibility for establishing "Contact Dermatitis: A Practice Parameter-Update 2015." This is a complete and comprehensive document at the current time. The medical environment is changing and not all recommendations will be appropriate or applicable to all patients. Because this document incorporated the efforts of many participants, no single individual, including members serving on the Joint Task Force, are authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information or interpretation of this practice parameter by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by the pharmaceutical industry in drug development or promotion. Previously published practice parameters of the Joint Task Force on Practice Parameters for Allergy & Immunology are available at http://www.JCAAI.org or http://www.allergyparameters.org.

In vitro dermal penetration of nickel nanoparticles

Nickel nanoparticles (NiNPs) represent a new type of occupational exposure because, due to the small size/high surface, they can release more Ni ions compared to bulk material. It has been reported a case of a worker who developed sensitization while handling nickel nanopowder without precautions. Therefore there is the need to assess whether the skin absorption of NiNPs is higher compared to bulk nickel. Two independent in vitro experiments were performed using Franz diffusion cells. Eight cells for each experiment were fitted using intact and needle-abraded human skin. The donor phase was a suspension of NiNPs with mean size of 77.7 ± 24.1 nm in synthetic sweat. Ni permeated both types of skin, reaching higher levels up to two orders of magnitude in the damaged skin compared to intact skin (5.2 ± 2.0 vs 0.032 ± 0.010 μg cm(-2), p = 0.006) at 24 h. Total Ni amount into the skin was 29.2 ± 11.2 μg cm(-2) in damaged skin and 9.67 ± 2.70 μg cm(-2) in intact skin (mean and SD, p = 0.006). Skin abrasions lead to doubling the Ni amount in the epidermis and to an increase of ten times in the dermis. This study demonstrated that NiNPs applied on skin surface cause an increase of nickel content into the skin and a significant permeation flux through the skin, higher when a damaged skin protocol was used. Preventive measures are needed when NiNPs are produced and used due to their higher potential to enter in our body compared to bulk nickel.

Hexavalent and trivalent chromium in leather: What should be done?

Trivalent chromium compounds are used for leather tanning, and chromium may be released during use of leather goods. In certain instances, small amounts of hexavalent chromium can be formed and released. Both trivalent and hexavalent chromium can elicit allergic skin reaction in chromium sensitised subjects, the latter being significantly more potent. Induction of sensitisation only occurs after exposure to hexavalent chromium. A minority of subjects are sensitised to chromium, and in a fraction of these subjects allergic skin reaction have been described after wearing leather shoes or, less frequently, other leather goods. The evidence that in all these cases the reaction is related to hexavalent chromium is not always strong. The content of hexavalent chromium in leather is regulated in European Union, but rate of release rather than content is relevant for allergic skin reaction. The role of trivalent chromium appear much less relevant if at all. Modern tanning procedure do not pose significant risk due to either hexavalent or trivalent chromium. Dismissing bad quality and worn-off leather goods is relevant in reducing or eliminating the skin reaction. It should also be pointed out that shoe components or substances other than chromium in leather may cause allergic/irritative skin reactions.

European Society of Contact Dermatitis guideline for diagnostic patch testing - recommendations on best practice

The present guideline summarizes all aspects of patch testing for the diagnosis of contact allergy in patients suspected of suffering, or having been suffering, from allergic contact dermatitis or other delayed-type hypersensitivity skin and mucosal conditions. Sections with brief descriptions and discussions of different pertinent topics are followed by a highlighted short practical recommendation. Topics comprise, after an introduction with important definitions, materials, technique, modifications of epicutaneous testing, individual factors influencing the patch test outcome or necessitating special considerations, children, patients with occupational contact dermatitis and drug eruptions as special groups, patch testing of materials brought in by the patient, adverse effects of patch testing, and the final evaluation and patient counselling based on this judgement. Finally, short reference is made to aspects of (continuing) medical education and to electronic collection of data for epidemiological surveillance.

Potential health effects associated with dermal exposure to occupational chemicals

There are a large number of workers in the United States, spanning a variety of occupational industries and sectors, who are potentially exposed to chemicals that can be absorbed through the skin. Occupational skin exposures can result in numerous diseases that can adversely affect an individual's health and capacity to perform at work. In general, there are three types of chemical-skin interactions of concern: direct skin effects, immune-mediated skin effects, and systemic effects. While hundreds of chemicals (metals, epoxy and acrylic resins, rubber additives, and chemical intermediates) present in virtually every industry have been identified to cause direct and immune-mediated effects such as contact dermatitis or urticaria, less is known about the number and types of chemicals contributing to systemic effects. In an attempt to raise awareness, skin notation assignments communicate the potential for dermal absorption; however, there is a need for standardization among agencies to communicate an accurate description of occupational hazards. Studies have suggested that exposure to complex mixtures, excessive hand washing, use of hand sanitizers, high frequency of wet work, and environmental or other factors may enhance penetration and stimulate other biological responses altering the outcomes of dermal chemical exposure. Understanding the hazards of dermal exposure is essential for the proper implementation of protective measures to ensure worker safety and health.

Formal recycling of e-waste leads to increased exposure to toxic metals: an occupational exposure study from Sweden

Electrical and electronic waste (e-waste) contains multiple toxic metals. However, there is currently a lack of exposure data for metals on workers in formal recycling plants. The objective of this study was to evaluate workers' exposure to metals, using biomarkers of exposure in combination with monitoring of personal air exposure. We assessed exposure to 20 potentially toxic metals among 55 recycling workers and 10 office workers at three formal e-waste recycling plants in Sweden. Workers at two of the plants were followed-up after 6 months. We collected the inhalable fraction and OFC (37-mm) fraction of particles, using personal samplers, as well as spot samples of blood and urine. We measured metal concentrations in whole blood, plasma, urine, and air filters using inductively coupled plasma-mass spectrometry following acid digestion. The air sampling indicated greater airborne exposure, 10 to 30 times higher, to most metals among the recycling workers handling e-waste than among the office workers. The exposure biomarkers showed significantly higher concentrations of chromium, cobalt, indium, lead, and mercury in blood, urine, and/or plasma of the recycling workers, compared with the office workers. Concentrations of antimony, indium, lead, mercury, and vanadium showed close to linear associations between the inhalable particle fraction and blood, plasma, or urine. In conclusion, our study of formal e-waste recycling shows that workers performing recycling tasks are exposed to multiple toxic metals.

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.