The effect of repeated open exposure to low levels of nickel on compromised hand skin of nickel-allergic subjects

Health impact assessment of a skin sensitizer: Analysis of potential policy measures aimed at reducing geraniol concentrations in personal care products and household cleaning products

A methodology to assess the health impact of skin sensitizers is introduced, which consists of the comparison of the probabilistic aggregated exposure with a probabilistic (individual) human sensitization or elicitation induction dose. The health impact of potential policy measures aimed at reducing the concentration of a fragrance allergen, geraniol, in consumer products is analysed in a simulated population derived from multiple product use surveys. Our analysis shows that current dermal exposure to geraniol from personal care and household cleaning products lead to new cases of contact allergy and induce clinical symptoms for those already sensitized. We estimate that this exposure results yearly in 34 new cases of geraniol contact allergy per million consumers in Western and Northern Europe, mainly due to exposure to household cleaning products. About twice as many consumers (60 per million) are projected to suffer from clinical symptoms due to re-exposure to geraniol. Policy measures restricting geraniol concentrations to <0.01% will noticeably reduce new cases of sensitization and decrease the number of people with clinical symptoms as well as the frequency of occurrence of these clinical symptoms. The estimated numbers should be interpreted with caution and provide only a rough indication of the health impact.

Contact allergy and human biomonitoring--an overview with a focus on metals

Humans are widely exposed to chemicals. Today, there is an increased acknowledgement of the importance of measuring human and environmental exposures to man-made or refined chemicals. Different approaches have been applied over time, but during the past 25 years, there has been a general trend towards the use of human biomonitoring. A few studies have used human biomonitoring methodology to track contact allergens together with information on patch test reactivity. Hypothetically, the internal load of reactive chemicals might modify the immune response to haptens and the propensity to sensitize and elicit allergic contact dermatitis or develop tolerance. This review offers a general overview of human biomonitoring, including information about its typical application and methodology. Furthermore, studies that have attempted to perform simultaneous biomonitoring and patch testing are reviewed. It is concluded that all studies conducted until the present have focused on one or two routes of exposure (typically skin and oral exposure, but also skin and airway exposure), whereas no studies have investigated all routes at the same time. Also, there is a need for prospective studies, as all epidemiological studies so far have been cross-sectional.

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.

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.

Reactivity to euro coins and sensitization thresholds in nickel-sensitive subjects

BACKGROUND

The 1- and the 2-euro coins consist of nickel alloys, which release nickel. The nickel released by far exceeds the amount allowed by the European Union Nickel Directive referring to products intended to come into direct and prolonged contact with the skin. As there is only temporary contact with the skin, the clinical relevance of nickel-containing coins with regard to nickel dermatitis is a matter of debate, although there is evidence that the nickel released from the coins affects some nickel-sensitive subjects through occupational exposure.

OBJECTIVES

Our aim was to study skin reactivity to euro coins, and to correlate the frequency and intensity of coin patch test responses to sensitization thresholds to nickel.

PATIENTS AND METHODS

Sixty-four nickel-sensitized and 30 non-nickel-sensitized subjects were patch tested with serial dilutions of nickel sulfate (5, 1, 0.5, 0.1, 0.05, 0.01 and 0.005% in distilled water) and with coins. Italian coins (500, 200, 100 and 50 lira) and euro coins (2 and 1 euros, 20 and 5 euro cents) were used for patch testing and compared.

RESULTS

The application of 1- and 2-euro coins to the skin induced eczematous reactions, being more frequent and intense in comparison with those provoked by other coins. A correlation between intensity of responses to coin patch tests and sensitization threshold to nickel was observed. Patients with the strongest reactions to 1- and 2-euro coins showed positive responses to the lowest nickel concentrations.

CONCLUSIONS

The nickel content in euro coins represents a possible health hazard, especially for highly nickel-sensitive subjects. We recommend that nickel sulfate patch tests should be performed at different concentrations to determine sensitization thresholds at least in individuals with occupational exposure to coins.

Augmentation of skin response by exposure to a combination of allergens and irritants - a review

Clinical experimental studies on contact dermatitis (CD) often evaluate the effect of one allergen or one irritant at a time. In real life, the skin is often exposed to more allergens, more irritants or allergens and irritants in combination. This combined exposure may potentially influence irritant effects as well as allergenicity of the substances. Mechanisms for a changed response can be immunological effects or enhanced penetration. Knowledge about the influence on skin reaction of combined exposures may influence skin reactivity and is important for prevention of CD. For allergens, threshold values may be influenced by the presence of other allergens or irritants, and prevention of CD by regulation of threshold values may not be sufficient if this is not taken into account.

Proposal for a risk assessment methodology for skin sensitization based on sensitization potency data

In this paper, we propose a quantitative risk assessment methodology for skin sensitization aiming at the derivation of 'safe' exposure levels for sensitizing chemicals, used e.g., as ingredients in consumer products. Given the limited number of sensitizers tested in human sensitization tests, such as the human repeat-insult patch test (HRIPT) or the human maximization test (HMT), we used EC3 values from the local lymph node assay (LLNA) in mice because they provide the best quantitative measure of the skin sensitizing potency of a chemical. A comparison of LLNA EC3 values with HRIPT and HMT LOEL, and NOEL values was carried out and revealed that the EC3, expressed as area dose, can be used as a surrogate value for the human NOEL in risk assessment. The uncertainty/extrapolation factor approach was used to derive (a) an 'acceptable non-sensitizing area dose' (ANSAD) to protect non-allergic individuals against skin sensitization and (b) an 'acceptable non-eliciting area dose' (ANEAD) to protect allergic individuals against elicitation of allergic contact dermatitis. For ANSAD derivation, interspecies, intraspecies and time extrapolation factors are applied to the LLNA EC3. For ANEAD derivation, additional application of a variable sensitization-elicitation extrapolation factor is proposed. Values for extrapolation factors are derived and discussed, the proposed methodology is applied to the sensitizers methylchloroisothiazolinone/methylisothiazolinone, cinnamic aldehyde and nickel and results are compared to published risk assessments.

Influence of a detergent on skin response to methyldibromo glutaronitrile in sensitized individuals

The present study was undertaken to evaluate the combined effect of the preservative methyldibromo glutaronitrile (MDBGN) and sodium lauryl sulfate (SLS) on the elicitation response of allergic contact dermatitis. 20 volunteers with contact allergy to MDBGN were patch tested with 5 concentrations (10, 50, 100, 500 and 1000 p.p.m.) of MDBGN alone and in combination with 0.25% SLS on the upper arms for 24 h. Skin reactions were evaluated by clinical scoring, and data were evaluated by logistic dose-response models. Additionally, evaluation of skin reactions was performed by measurement of transepidermal water loss (TEWL) and skin colour. Measurements were obtained at baseline and at D3 and D7. As evaluated by clinical assessment, allergic reactions to MDBGN were elicited at lower concentrations when applied in combination with SLS than when applied alone. The response was augmented by a factor of 6.4. An increased response to combined exposure to SLS and MDBGN as compared with MDBGN alone was confirmed by TEWL and colour measurements. Effects of exposure time and concentration of the detergent are discussed. In conclusion, an augmented response was found after concurrent application of MDBGN and SLS. The response was augmented by a factor of 6.4, with confidence limits of 2.8-14.6 (P < 0.0001). This result is important in relation to the determination of threshold values and the risk assessment of contact allergens in consumer and industrial products, where allergens are often present in combination with surfactants.

A stronger patch test elicitation reaction to the allergen hydroxycitronellal plus the irritant sodium lauryl sulfate

Household and cleaning products often contain both allergens and irritants. The aim of this double-blinded, randomized, paired study was to determine whether patch testing with an allergen (hydroxycitronellal) combined with an irritant [sodium lauryl sulfate (SLS)] cause a stronger patch test elicitation reaction than patch testing with the allergen (hydroxycitronellal) alone, in patients previously patch tested positive to hydroxycitronellal. A stronger patch test elicitation reaction was defined as at least 1 day of patch test reading showing more positive patch tests (+, ++ or +++) on the forearm patch tested with 6 concentrations of SLS plus hydroxycitronellal than on the forearm tested with 6 concentrations of hydroxycitronellal alone and no day of patch test readings showing more positive tests on the hydroxycitronellal forearm. 15/20 (75%) had at least 1 day of patch test reading with more positive patch tests on the forearm patch tested with SLS plus hydroxycitronellal and no day of patch test readings with more positive patch tests on the forearm tested with hydroxycitronellal (P = 0.0253). Estimation of the blood flow with laser Doppler supported these findings.

Provocative use test of nickel coins in nickel-sensitized subjects and controls

BACKGROUND

Consensus exists on levels of nickel release that are well tolerated in exposure to nickel-containing items in direct and continuous contact with skin (e.g. watches). The clinical relevance of nickel-containing coins eliciting nickel dermatitis associated with extensive occupational exposure (e.g. coins handled by cashiers) has not been determined.

OBJECTIVES

To examine whether nickel-containing coins might be an elicitor of allergic contact dermatitis (ACD) in occupational settings with extensive exposure to coins (i.e. cashiers).

METHODS

Eighteen subjects (10 nickel sensitized and eight non-nickel sensitized) completed this study after screening of history, physical examination and diagnostic patch testing (5% nickel sulphate). Each volunteer handled 10 coins (nickel-containing coins or non-nickel-containing coins) in a cross-over design at 5-min intervals (5 min handling followed by 5 min rest) for 8 h per day, for a total of 12 days excluding the weekend. One hand was gloved while the other was not during coin handling. Visual scoring and bioengineering measurements were recorded at each of four predetermined sites at baseline (day 1), end of day 5 and day 12 (last day of exposure).

RESULTS

There were no statistical differences for either visual or bioengineering data comparing: (i) nickel-sensitized vs. non-nickel-sensitized subjects handling nickel-containing coins at day 1, day 5 and day 12; (ii) day 12 vs. day 1 (baseline) for nickel-sensitized subjects handling nickel-containing coins; (iii) handling of nickel-containing coins vs. non-nickel-containing coins by nickel-sensitized subjects at day 5 and day 12; (iv) gloved hand vs. ungloved hand of nickel-sensitized subjects handling nickel-containing coins at day 12. Limitations of the method and clinical extrapolation are detailed.

CONCLUSIONS

Individuals handling these nickel-containing coins daily did not develop ACD, as judged by visual signs or bioengineering parameters.

The fragrance hand immersion study - an experimental model simulating real-life exposure for allergic contact dermatitis on the hands

Recently, we showed that 10 x 2% of consecutively patch-tested hand eczema patients had a positive patch test to a selection of fragrances containing fragrances relevant to hand exposure. In this study, we used repeated skin exposure to a patch test-positive fragrance allergen in patients previously diagnosed with hand eczema to explore whether immersion of fingers in a solution with or without the patch-test-positive fragrance allergen would cause or exacerbate hand eczema on the exposed finger. The study was double blinded and randomized. All participants had a positive patch test to either hydroxycitronellal or Lyral (hydroxyisohexyl 3-cyclohexene carboxaldehyde). Each participant immersed a finger from each hand, once a day, in a solution containing the fragrance allergen or placebo. During the first 2 weeks, the concentration of fragrance allergen in the solution was low (approximately 10 p.p.m.), whilst during the following 2 weeks, the concentration was relatively high (approximately 250 p.p.m.), imitating real-life exposure to a household product like dishwashing liquid diluted in water and the undiluted product, respectively. Evaluation was made using a clinical scale and laser Doppler flow meter. 3 of 15 hand eczema patients developed eczema on the finger immersed in the fragrance-containing solution, 3 of 15 on the placebo finger and 3 of 15 on both fingers. Using this experimental exposure model simulating real-life exposure, we found no association between immersion of a finger in a solution containing fragrance and development of clinically visible eczema on the finger in 15 participants previously diagnosed with hand eczema and with a positive patch test to the fragrance in question.

Effect of prolonged exposure to low antigen concentration for sensitization

The local lymph node assay (LLNA) is an assay in mice to identify potential allergens. Compounds that do not induce a stimulation index (SI)>or=3 are not considered sensitizers. Of the chemicals that do, the SI of 3 is used as a benchmark, and indicates the sensitizing potency of a chemical. Compared to the exposure duration of the LLNA (3 days), real life exposure often lasts for months or years. We therefore investigated whether prolonged exposure to sensitizers at concentrations that do not induce a SI>or=3 in the LLNA, were able to surpass this threshold. Mice were treated for 2 months at 7-day intervals with a range of concentrations of the known allergens ethyl-p-aminobenzoate (benzocaine, BENZ), 2,4-dinitrochlorobenzene (DNCB), and tetramethyl thiuram disulfide (TMTD). Both proliferative activity and cytokine production were established at day 60. Neither BENZ nor TMTD showed a significant increase in the proliferation rate compared to vehicle controls. Only DNCB at concentrations originally above the EC(3) a significant increase in proliferation was seen after prolonged exposure. No significant effect on IFN-gamma and IL-4 production was observed for all three compounds compared. These findings indicate that for classification of sensitizers the shorter exposure period employed in the standard LLNA is sufficient, and longer periods of exposure have no bearing on this classification.

Allergic contact dermatitis elicitation thresholds of potent allergens in humans

Literature scoured for human allergenicity to individual chemicals yields a limited number of potent sensitizers, which can be classified in four categories: metals, botanicals, biocides and miscellany. Potency is defined as strong for substances eliciting eczematous reactions to patch concentrations of 500 ppm (parts per million) or less in sensitized individuals. Most data encountered stem from studies conducted on dermatology patients tested routinely for hypersensitivity; only few data have been generated by systematic serial dilution testing.

Effects of repeated skin exposure to low nickel concentrations: a model for allergic contact dermatitis to nickel on the hands

We studied the effects of repeated daily exposure to low nickel concentrations on the hands of patients with hand eczema and nickel allergy. The concentrations used were chosen to represent the range of trace to moderate occupational nickel exposure. The study was double-blinded and placebo controlled. Patients immersed a finger for 10 min daily into a 10-p.p.m. nickel concentration in water for the first week, and during the second week into a 100-p.p.m. nickel concentration. This regimen significantly increased (P = 0.05) local vesicle formation and blood flow (P = 0.03) as compared with a group of patients who immersed a finger into water. The nickel concentrations used also provoked significant inflammatory skin changes on sodium lauryl sulphate (SLS)-treated forearm skin of the patients, whereas inflammatory skin changes were not observed in healthy volunteers without hand eczema and nickel allergy, either on normal or on SLS-treated forearm skin. The present study strongly suggests that the changes observed were specific to nickel exposure. Standardized methods to assess trace to moderate nickel exposure on the hands, and the associated effects in nickel-sensitized subjects, are needed.

Cutaneous reactivity of the hands in nickel-sensitive patients with hand eczema

This study compares the cutaneous reactivity between the hand and the back for 7 female patients with active hand eczema, who were found to be nickel-sensitive on routine patch testing with the European standard series. Patients were patch tested to a dilution series of nickel sulfate on the back in order to determine the threshold concentration for elicitation of allergic contact dermatitis, and based upon this result a lower concentration of nickel was then used for patch tests on the hand. We found that in the majority of patients (6/7) the cutaneous responsiveness of the hand was not increased compared with that of the back. However, the hand of 1 patient was more sensitive to nickel and patch testing was accompanied with a flare of her eczema, which suggests that cutaneous hyperreactivity may be important in individual patients with hand eczema.

Is it possible to improve the prognosis in nickel contact dermatitis?

A questionnaire was sent to 143 patients who had shown a positive patch test reaction to nickel sulfate more than 10 years earlier. 91 patients returned the questionnaire, revealing that after the testing, 73 had suffered from dermatitis, 61 especially from hand dermatitis. 37 of these patients were clinically examined and patch tested with standard series and in addition, 12 patients were tested with nickel sulfate and nickel chloride with different occlusion times. At the clinic visit, 23 patients had dermatitis, 16 hand dermatitis, and 11 were symptom-free. 26 of the patients had metal items close to their skin and 21 of them had current dermatitis, 14 hand dermatitis. Of the 11 patients who had no metal exposure, 9 were symptom-free. The association of dermatitis with exposure to metal objects was statistically significant (p < 0.001). Those patients who had current dermatitis had also developed multiple allergies and reacted to nickel with shorter application times in patch tests, as compared to those who were symptom-free. It seemed possible that the prognosis for nickel dermatitis could be improved if nickel-allergic patients would strictly avoid metal contact, especially in clothing and jewelry.

Atopic dermatitis, nickel sensitivity and xerosis as risk factors for hand eczema in women

Knowledge of the relationship between a history of atopic dermatitis and nickel sensitivity as risk factors for hand eczema is limited. Our objective was to study the relative importance of atopic manifestations and nickel sensitivity as risk factors for hand eczema in women. From women referred for patch testing with a dental series, 100 consecutive nickel-positive and 95 nickel-negative patients were studied. A history of atopic manifestations and a history of 5 symptoms of hand eczema, i.e., dry erythemas, maculopapules, vesicles, erosions and hyperkeratoses were recorded. A history of atopic dermatitis was found to increase the risk of the 5 symptoms of hand eczema and sick leave due to hand eczema highly significantly. Nickel sensitivity increased only the risk of vesicles and erosions. Xerosis increased the risk of dry erythemas and vesicles. We concluded that a history of atopic dermatitis was more important than nickel sensitivity as a risk factor for hand eczema in women.