Nickel, chromium and cobalt in consumer products: revisiting safe levels in the new millennium

Highly selective colorimetric chemosensor for Co2+

A new highly selective colorimetric chemosensor for Co(2+) was developed based on coumarin-conjugated thiocarbanohydrazone. The ligand senses Co(2+) in solution by changing its color from light yellow to deep pink. The sensor has been used in the development of practically viable colorimetric kits and as a staining agent for Co(2+) in microorganisms.

Particles, sweat, and tears: a comparative study on bioaccessibility of ferrochromium alloy and stainless steel particles, the pure metals and their metal oxides, in simulated skin and eye contact

Ferrochromium alloys are manufactured in large quantities and placed on the global market for use as master alloys (secondary raw materials), primarily for stainless steel production. Any potential human exposure to ferrochromium alloy particles is related to occupational activities during production and use, with 2 main exposure routes, dermal contact and inhalation and subsequent digestion. Alloy and reference particles exposed in vitro in synthetic biological fluids relevant for these main exposure routes have been investigated in a large research effort combining bioaccessibility; chemical speciation; and material, surface, and particle characteristics. In this paper, data for the dermal exposure route, including skin and eye contact, will be presented and discussed. Bioaccessibility data have been generated for particles of a ferrochromium alloy, stainless steel grade AISI 316L, pure Fe, pure Cr, iron(II,III)oxide, and chromium(III)oxide, upon immersion in artificial sweat (pH 6.5) and artificial tear (pH 8.0) fluids for various time periods. Measured released amounts of Fe, Cr, and Ni are presented in terms of average Fe and Cr release rates and amounts released per amount of particles loaded. The results are discussed in relation to bulk and surface composition of the particles. Additional information, essential to assess the bioavailability of Cr released, was generated by determining its chemical speciation and by providing information on its complexation and oxidation states in both media investigated. The effect of differences in experimental temperature, 30 degrees C and 37 degrees C, on the extent of metal release in artificial sweat is demonstrated. Iron was the preferentially released element in all test media and for all time periods and iron-containing particles investigated. The extent of metal release was highly pH dependent and was also dependent on the medium composition. Released amounts of Cr and Fe were very low (close to the limit of detection, <0.008% of particles released or dissolved as iron or chromium) for the alloy particles (ferrochromium alloy and stainless steel), the pure Cr particles, and the metal oxide particles. The released fraction of Cr (Cr/[Cr + Fe]) varied with the material investigated, the test medium, and the exposure time and cannot be predicted from either the bulk or the surface composition. Chromium was released as noncomplexed Cr(III) and in addition in very low concentrations (<3 microg/L). Nickel released was under the limit of detection (0.5 microg/L), except for ultrafine stainless steel particles (<10 microg/L). It is evident that media chemistry and material properties from a bulk and surface perspective, as well as other particle characteristics, and the chemical speciation of released metals have to be considered when assessing any potential hazard or risk induced by sparingly soluble metal or alloy particles.

Metal allergy--a review on exposures, penetration, genetics, prevalence, and clinical implications

The prevalence of metal allergy is high in the general population, and it is estimated that up to 17% of women and 3% of men are allergic to nickel and that 1-3% are allergic to cobalt and chromium. Among dermatitis patients, the prevalence of metal allergy is even higher. Metal allergy is mainly an environmental disorder although null mutations in the filaggrin gene complex were recently found to be associated with nickel allergy and dermatitis. Environmental metal exposures include jewelry, buttons, clothing fasteners, dental restorations, mobile phones, and leather. Although consumer exposure is responsible for most cases of metal allergy, the importance of occupational metal exposure remains present and should always be taken into consideration when one interprets allergic patch test reactions to metals. Traditionally, nickel, cobalt, and chromium have been the most important contact allergens. However, recently, gold and palladium have drawn much attention as the prevalence of contact allergy to these metals is high. Palladium allergy is mainly a result of cross-sensitization to nickel, whereas gold allergy is rarely clinically relevant when one takes its high prevalence into account. The epidemiology of metal allergy has recently changed in Europe as nickel allergy among ear-pierced Danish women has decreased following regulatory intervention on nickel release from consumer products. In the United States, the prevalence of nickel allergy is still increasing, which may be explained by the absence of regulation. The prevalence of chromium allergy is increasing in the United States, Singapore, and Denmark among dermatitis patients. This increase is significantly associated with leather exposure in Denmark. Metal allergy may result in allergic contact dermatitis and systemic allergic (contact) dermatitis. Furthermore, metal allergy has been associated with device failure following insertion of intracoronary stents, hip and knee prostheses, as well as other implants. This area is in need of more research.

Market survey on toxic metals contained in tattoo inks

Tattooing practice is adopted worldwide and represents an important socio-cultural phenomenon, but, the injection into the skin of coloring agents as metals might pose a risk for allergies and other skin inflammations as well as for systemic diseases. In this context, 56 inks for tattooing purchased from 4 different supply companies were analyzed for metal concentration. Aliquots of pigments were microwave digested by nitric acid, fluoridric acid and hydrogen-peroxide and Al, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Sr and V were quantified by sector field inductively coupled plasma mass spectrometry. Limits of quantification varied from 0.07 ng/ml (Cd) to 10 ng/ml (Al and Fe); recoveries ranged from 92% (Cd and Sb) to 109% (Sr); within- and between-day precisions were 3.2% and 4.67% on average. The relative contribution of metals to the tattoo inks composition was highly variable between brands and colors, even in pigments with the same base color. Elements found as the main components of inks were as follows (in microg/g): Al, 1.59-5893; Ba, 0.058-1226; Cu, 0.076-31,310; Fe, 0.717-88,443; Sr, 0.174-36.4. Toxic metals as Cd, Mn, Pb, Sb and V were over the 1 microg/g in a few cases, while Hg was in traces. Among the allergenic metals, Cr was the highest (0.315-147 microg/g), followed by Ni (0.037-9.59 microg/g) and Co (0.0028-6.43 microg/g) then. On 56 tattoo inks, Cr, Ni and Co exceeded the safe allergological limit of 1 microg/g in 62.5%, 16.1% and 1.8% of cases, respectively.

Potency values from the local lymph node assay: application to classification, labelling and risk assessment

Hundreds of chemicals are contact allergens but there remains a need to identify and characterise accurately skin sensitising hazards. The purpose of this review was fourfold. First, when using the local lymph node assay (LLNA), consider whether an exposure concentration (EC3 value) lower than 100% can be defined and used as a threshold criterion for classification and labelling. Second, is there any reason to revise the recommendation of a previous ECETOC Task Force regarding specific EC3 values used for sub-categorisation of substances based upon potency? Third, what recommendations can be made regarding classification and labelling of preparations under GHS? Finally, consider how to integrate LLNA data into risk assessment and provide a rationale for using concentration responses and corresponding no-effect concentrations. Although skin sensitising chemicals having high EC3 values may represent only relatively low risks to humans, it is not possible currently to define an EC3 value below 100% that would serve as an appropriate threshold for classification and labelling. The conclusion drawn from reviewing the use of distinct categories for characterising contact allergens was that the most appropriate, science-based classification of contact allergens according to potency is one in which four sub-categories are identified: 'extreme', 'strong', 'moderate' and 'weak'. Since draining lymph node cell proliferation is related causally and quantitatively to potency, LLNA EC3 values are recommended for determination of a no expected sensitisation induction level that represents the first step in quantitative risk assessment.

Management of contact dermatitis due to nickel allergy: an update

Nickel is the major cause of allergic contact dermatitis in the general population, both among children and adults, as well as in large occupational groups. This metal is used in numerous industrial and consumer products, including stainless steel, magnets, metal plating, coinage, and special alloys, and is therefore almost impossible to completely avoid in daily life. Nickel contact dermatitis can represent an important morbidity, particularly in patients with chronic hand eczema, which can lead to inability to work, a decrease in quality of life and significant healthcare expenses. Therefore, its management is of great importance. This article reviews diagnostic, preventive and therapeutic strategies in this field.

Evidence that two alkyl ester quaternary ammonium compounds lack substantial human skin-sensitizing potential

BACKGROUND

Alkyl ester quaternary ammonium compounds (ester quats) are used extensively in fabric rinse conditioners. It is important to document in the literature the outcome of historical studies that were performed to assess the risk of adverse skin effects associated with their use.

OBJECTIVES

(1) To document the outcomes of historical studies performed to evaluate the skin sensitizing potential of two ester quats (the di-[hardened tallow fatty acid] ester of 2,3-dihydroxypropyl-trimethyl ammonium chloride [HEQ] and the dialkyl ester of triethanol ammonium methyl sulfate [TEA-Quat]) and (2) to demonstrate that these ester quats lack marked skin-sensitizing potential in humans, such that they do not present a risk of contact allergy for consumers who use fabric rinse conditioners.

METHODS

Each material was assessed in the human maximization test in a panel of 25 volunteers. Diagnostic patch testing was also performed with each material in a population of 239 patients undergoing routine patch testing for suspected allergic contact dermatitis. These data are also considered in the context of an exposure-based quantitative risk assessment.

RESULTS

Neither HEQ nor TEA-Quat was found to cause skin sensitization under the conditions of the human maximization test. No evidence of contact allergy to the materials was found among the relatively small population assessed by diagnostic patch testing.

CONCLUSIONS

This study provides evidence that HEQ and TEA-Quat lack substantial skin-sensitizing potential in humans. Taken together with similar data for other ester quats, it suggests that compounds in this class are unlikely to be significant human contact allergens.

Levels of nickel and other potentially allergenic metals in Ni-tested commercial body creams

It is extensively well-known that Ni and other metals occurring as impurities in cosmetic products might give rise to contact dermatitis in subjects with pre-existing allergy. The present study on the content of 13 metals (Cd, Co, Cr, Cu, Hg, Ir, Mn, Ni, Pb, Pd, Pt, Rh, and V) in moisturizing creams, labelled as "Ni-tested" (i.e., Ni content <100 ng g(-1)) and available on the Italian market, provides a basis for assessing their safety for consumers. Quantification of metals was performed by sector field inductively coupled plasma mass spectrometry after microwave-assisted acid digestion of products. The developed method had limits of quantification less than 0.8 ng g(-1) for all the elements; recovery was in the interval 88% (Cd, Co) to 110% (Hg), and precision was always under 7%. Nickel was present in all the products with levels between 17.5 and 153 ng g(-1); three skin creams were slightly above the concentration reported on the label. The other elements were at levels below 1 microg g(-1). The highest concentrations, in ng g(-1), of Co, Cr, Cu, and Mn were 222, 303, 51.2, and 59.9, respectively. Mean Cd, Pb, and V were below 5 ng g(-1), while Hg was absent in all the samples. Among the new emergent allergens, Ir and Rh were in traces or even undetectable, while Pt had levels of 2.65 and 6.28 ng g(-1) in two creams and Pd was equal to 1.07 ng g(-1) in one product. The overall results are below the sensitizing limit proposed for consumer products and, thus, probably have no significant toxicological effects. Nevertheless, some creams presented amounts of Co and Cr comparable to those of Ni and therefore they have to be monitored in consideration of their cross-reactivity as well.

Contact sensitizer potassium dichromate alters lymphocyte populations in draining lymph nodes and blood in mice

ABSTRACT Chromium is a common human contact allergen, but it is not known whether chromates cause contact hypersensitivity by immunological mechanisms similar to those induced by strong haptens. To understand the immunological events of contact hypersensitivity to chromates, we investigated whether and how chromate sensitization alters lymphocyte subsets in draining lymph nodes (DLNs), blood, and spleens in mice. BALB/c mice were sensitized by painting their ears with 0.5% potassium dichromate or vehicle alone on 3 consecutive days. Flow cytometric analysis of lymphocyte surface antigens showed that the chromate exposure significantly increased the percentage of B cells and decreased the percentages of T cells in the DLNs. This was accompanied by a relative increase in T cells and a relative decrease in B cells in peripheral blood. In contrast to the chromate, sodium dodecyl sulfate (a skin irritant) did not affect B cells or T cells in the three compartments. Moreover, sensitization to the chromate led to dose-dependent decreases in the percentages of CD4(+) T cells and CD8(+) T cells in the DLNs. However, CD4(+) and CD8(+) memory T cells were significantly increased in the blood and DLNs of the chromate-sensitized mice. Additionally, the percentage of B cells in the DLNs but not blood was dose-dependently increased in the chromate-sensitized mice. Histologically, B-cell areas were dramatically enlarged in the DLNs of the chromate-sensitized mice. Thus, this report provides basic information to further elucidate the role of individual lymphocyte subsets in contact hypersensitivity to chromates.

[Occupational asthma caused by chromium and nickel]

We report the case of a 40-year-old woman who developed occupational asthma following exposure to chromium and nickel in the nickel-plating section of a metalworks company. Skin prick tests for specific antibodies proved positive for nickel chloride at a concentration of 1 mg/mL and negative for potassium dichromate. The specific bronchial provocation test confirmed the diagnosis of occupational asthma due to exposure to chromium and nickel. The patient presented a late positive reaction to nickel chloride (0.1 mg/mL) and an immediate positive reaction to a 10 mg/mL solution of potassium dichromate. These results indicate a dual response to nickel and chromium in this patient.

Fragrance allergy: assessing the risk from washed fabrics

The prevalence of contact allergy to fragrance ingredients increased during the last part of the 20th century with the consequence that a substantial number of individuals are at risk of experiencing allergic contact dermatitis (ACD) if they have a sufficient degree of skin exposure to the chemical to which they have become sensitized. Such exposure does not necessarily have to arise from the type of source that originally induced the sensitization. A number of sources of exposure are clearly associated with risk of elicitation of ACD, but the role of fragrance deposited on fabrics, for example as a result of laundry processes, also can be questioned. In this article, firstly, the risk of the induction of fragrance-related ACD from exposure to fragrance via fabric is considered. Using a quantitative risk-assessment approach, the risk appears to be extremely low. The possibility that fragrance residues on laundered fabrics might elicit reactions in those already sensitized by a different route is also discussed. Clinically, clothing pattern dermatitis associated with fragrance allergy is almost never observed, although this could be investigated clinically by exposing sensitized individuals to the relevant fragrance allergen.

Capillary electrophoresis hyphenated to inductively coupled plasma-sector field-mass spectrometry for the detection of chromium species after incubation of chromium in simulated sweat

The presence of chromium in chromium-tanned leather represents a considerable health problem since it can lead to chronic allergic contact dermatitis. Apart from trivalent chromium (Cr(III)), which is used for tanning, leather often contains hexavalent chromium (Cr(VI)), resulting from the oxidation of Cr(III) during the tanning process. This study deals with the chromium compounds in simulated sweat when brought into contact with Cr(III) or Cr(VI) and with chromium-tanned leathers. A capillary electrophoresis (CE) method was developed, with inductively coupled plasma-sector field-mass spectrometry (ICP-SF-MS) for element-specific detection. Two different electrophoretic runs, applying once the positive and once the negative polarity mode, were necessary for the detection of positively and negatively charged chromium species. Although sometimes described in the literature, a pre-run derivatization of the chromium-species was not performed here to prevent species transformation. 50 mmol.L(-1) sodium phosphate at a pH of 2.5 was used as CE separation buffer and as make-up liquid for the CE-ICP-SF-MS interface. When applied to simulated sweat samples incubated with Cr(VI), this method showed that methionine is responsible for the reduction of Cr(VI) into Cr(III), which, at its turn, forms a complex with lactic acid. In the case of sweat plus Cr(III), the latter step was also seen. Applied to simulated sweat in contact with leather samples, the method developed showed the presence of the former species among a much more complex pattern.