The dose-response relationship between the patch test and ROAT and the potential use for regulatory purposes

Heavy metals in contact dermatitis: A review

Contact dermatitis is an inflammatory skin reaction caused by direct contact with chemical substances in the environment and can either be irritant or allergic in nature. The clinical symptoms of contact dermatitis, include local skin rash, itching, redness, swelling, and lesions. Nowadays, 15-20% of people have some degree of contact dermatitis, which can be more or less severe. Immune responses in allergic contact dermatitis (ACD) are due to the effects of cytokines and allergen-specific CD4⁺ and CD8⁺ T cells on the skin. Acids and alkalis such as drain cleaners, plants such as poinsettias, hair colors, and nail polish remover, are all prominent causes of irritant contact dermatitis (ICDs). Heavy metals are metallic elements with a high atomic weight that are hazardous in low quantities and are known to cause dermatitis after systemic or local exposure. Nickel (Ni), chromium (Cr), lead (Pb), and copper (Cu) are among the most common heavy metals used in various industries. Metal allergies may cause ACD and also systemic contact dermatitis (SCD). Contact dermatitis is detected by laboratory tests such as patch testing, lymphocyte stimulation test (LST), and evaluation of cytokine production by primary cultures of peripheral blood mononuclear cells. This article presents an update on the epidemiological and clinical characteristics of ACD and SCD caused by three heavy metals (Cr, Cu, and Pb). Ni is not discussed due to recent coverage. Furthermore, the effects of contact sensitivity to some other heavy metals, such as gold (Au), cobalt (Co), palladium (Pd), and mercury (Hg) are discussed.

Preservatives in non-cosmetic products: Increasing human exposure requires action for protection of health

The widespread use of skin sensitizing preservatives is well-known. Contact allergy to preservatives is often caused by their presence in cosmetic products. Preservative use in non-cosmetic products is less well-known. We have reviewed European Union (EU) legislations on classification and labelling, biocides and cosmetics, concerning conditions for use of the most used sensitizing preservatives (including formaldehyde-releasing substances, isothiazolinones and parabens). We have analysed temporal trends in their use in non-cosmetic products (tonnes, number of products, concentrations), based on annual reports to the Swedish Products Register 1995-2018; and we discuss implications for stakeholders. Major changes over time are that the use of most of the preservatives has increased by tonnes and/or by number of products, and that several use concentrations have declined following harmonized classification as a skin sensitizer with low concentration limits for this classification. We conclude that the massive increase in use of preservatives is alarming, and that urgent action is needed for protection of health. Their use in non-cosmetic products is broad, increasing and often undisclosed. In the EU, legislations concerning chemicals can provide relevant restrictions to reduce their use and associated health risks, monitored by efficient surveillance. Prevention would be benefited by better coordination between legislations.

Quantitative risk assessment of allergens leaching from menstrual hygiene products

Allergic contact dermatitis (ACD) often associated with the topical use of perfumed products, remains one of the most common chronic skin disorders in Western countries. Since labelling of scented menstrual hygiene products (MHPs) is not mandatory, women might be unknowingly exposed to allergens. Given that vaginal mucosae lack the vital barrier function of the skin, skin allergens can easily penetrate and become systemically available and hence women may experience adverse effects in the anogenital region. The aim of this study was therefore to investigate whether women using scented MHPs are at risk of sensitization and hence developing ACD. Hereto, a Quantitative Risk Assessment (QRA) is performed on four well-known skin sensitizing chemicals (α-isomethyl ionone, benzyl salicylate, hexyl cinnamaldehyde and heliotropine) that were previously found leaching from five different scented MHPs including tampons and sanitary pads. The amounts of heliotropine, leached by one of the investigated tampons, exceeded acceptable exposure levels determined with the QRA and could induce sensitization. In addition, although no sensitization is expected for the other three compounds, an allergenic reaction might be provoked in women who are already sensitized. Labelling of allergens on scented MHPs would therefore help consumers to prevent adverse effects linked to ACD.

Contact dermatitis

Contact dermatitis (CD) is among the most common inflammatory dermatological conditions and includes allergic CD, photoallergic CD, irritant CD, photoirritant CD (also called phototoxic CD) and protein CD. Occupational CD can be of any type and is the most prevalent occupational skin disease. Each CD type is characterized by different immunological mechanisms and/or requisite exposures. Clinical manifestations of CD vary widely and multiple subtypes may occur simultaneously. The diagnosis relies on clinical presentation, thorough exposure assessment and evaluation with techniques such as patch testing and skin-prick testing. Management is based on patient education, avoidance strategies of specific substances, and topical treatments; in severe or recalcitrant cases, which can negatively affect the quality of life of patients, systemic medications may be needed.

Validation of questionnaire algorithm based on repeated open application testing with the constituents of fragrance mix II: the EDEN Fragrance Study

BACKGROUND

In a European study on contact allergy in the general population, it has been hypothesized that the combination of contact allergy to a fragrance together with a history indicating dermatitis at exposure and thereafter subsequent avoidance of scented products implied a diagnosis of allergic contact dermatitis.

OBJECTIVES

The primary aim of this study was to validate this hypothesis/algorithm. The secondary aim was to investigate whether there was any association between the outcome of the recent repeated open application test (ROAT) and the patch test reactivity.

METHODS

One hundred nine subjects with and without contact allergy to fragrance mix II (FM II) were recruited. Volunteers from six European dermatology clinics participated in the study including a patch test and a ROAT.

RESULTS

Twenty-four positive ROAT reactions were noted in total including 20 of those 32 with contact allergy to FM II. None of the volunteers reacted to the vehicle (P < 0.001). More individuals with a positive algorithm had positive ROATs when compared with those with a negative algorithm. However, the difference was not statistically significant (P = 0.12). The lower the patch test concentration eliciting a positive test reaction, the more likely was a positive ROAT and the more likely that the positive ROAT appeared early during the investigative period.

CONCLUSIONS

The algorithm used in this study was not validated but it was indicated in this ROAT setup. The stronger the patch test reactivity the more likely was a positive ROAT and the more likely it was that the positive ROAT appeared early during the application period.

Chromium and leather: a review on the chemistry of relevance for allergic contact dermatitis to chromium

Abstract

As other causes decline in importance, chromium-tanned leather has become a more important source for chromium allergy, which affects around 1% of the general population. The aim of this review is to give suggestions on how to minimize the risk of leather-related allergic contact dermatitis, which can be elicited in chromium-allergic persons by hexavalent and trivalent chromium released from leather. Hexavalent chromium is the more potent chromium form and requires a lower skin dose to elicit allergic reactions. It is formed on the surface of some, antioxidant-free, leathers at dry conditions (< 35% relative humidity) and is influenced by the tanning process and other conditions, such as UV irradiation, contact with alkaline solutions, and leather age. Trivalent chromium is the dominant form released from chromium-tanned leather and its released amount is sufficient to elicit allergic reactions in some chromium-allergic individuals when they are exposed repetitively and over longer time (days – months). A low initial test result (< 3 mg/kg) for hexavalent chromium with the current standard test (ISO 17075) does not guarantee a low release of chromium from the leather or a low release of hexavalent chromium under typical exposure conditions during the service life of the leather. Information, labels, and certificates regarding leather products are often insufficient to protect chromium-allergic individuals. Correct labelling and information on the possible content of different allergens, as well as different tanning alternatives for certain leather products, are crucial.

Graphical abstract

Risks of Allergic Contact Dermatitis Elicited by Nickel, Chromium, and Organic Sensitizers: Quantitative Models Based on Clinical Patch Test Data

Risks of allergic contact dermatitis (ACD) from consumer products intended for extended (nonpiercing) dermal contact are regulated by E.U. Directive EN 1811 that limits released Ni to a weekly equivalent dermal load of ≤0.5 μg/cm² . Similar approaches for thousands of known organic sensitizers are hampered by inability to quantify respective ACD-elicitation risk levels. To help address this gap, normalized values of cumulative risk for eliciting a positive ("≥+") clinical patch test response reported in 12 studies for a total of n = 625 Ni-sensitized patients were modeled in relation to observed ACD-eliciting Ni loads, yielding an approximate lognormal (LN) distribution with a geometric mean and standard deviation of GM_Ni = 15 μg/cm² and GSD_Ni = 8.0, respectively. Such data for five sensitizers (including formaldehyde and 2-hydroxyethyl methacrylate) were also ∼LN distributed, but with a common GSD value equal to GSD_Ni and with heterogeneous sensitizer-specific GM values each defining a respective ACD-eliciting potency GM_Ni /GM relative to Ni. Such potencies were also estimated for nine (meth)acrylates by applying this general LN ACD-elicitation risk model to respective sets of fewer data. ACD-elicitation risk patterns observed for Cr(VI) (n = 417) and Cr(III) (n = 78) were fit to mixed-LN models in which ∼30% and ∼40% of the most sensitive responders, respectively, were estimated to exhibit a LN response also governed by GSD_Ni . The observed common LN-response shape parameter GSD_Ni may reflect a common underlying ACD mechanism and suggests a common interim approach to quantitative ACD-elicitation risk assessment based on available clinical data.

Chromium(III) release from chromium-tanned leather elicits allergic contact dermatitis: a use test study

Background

Chromium (Cr) is a common skin sensitizer. The use of Cr(VI) in leather is restricted in the EU, but that of Cr(III) is not.

Objectives

To assess whether prolonged exposure to Cr‐tanned leather with mainly Cr(III) release may elicit allergic contact dermatitis in Cr‐allergic individuals.

Method

Ten Cr‐allergic subjects and 22 controls were patch tested with serial dilutions of Cr(III) and Cr(VI), and with leather samples. They then conducted a use test with a Cr‐tanned and a Cr‐free leather bracelet over a period of 3 weeks, for 12 h per day. Cr deposited on the skin from the bracelets was measured in the controls, and the diphenylcarbazide test for Cr(VI) and extraction tests for Cr(III) and Cr(VI) were conducted for the different leathers.

Results

Four of 10 Cr‐allergic subjects developed positive reactions to the Cr‐tanned bracelet within 7–21 days, whereas only 1 of 10 had a positive patch test reaction to this leather. Cr released from the Cr‐tanned leather was most probably entirely Cr(III), with a quantifiable amount being deposited on the skin.

Conclusions

This study strongly suggests that prolonged and repeated exposure to Cr‐tanned leather with mainly Cr(III) release is capable of eliciting allergic contact dermatitis in Cr‐allergic individuals.

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.

Immunotoxicology and its application in risk assessment

Immunotoxicology is the study of undesired modulation of the immune system by extrinsic factors. Toxicological assessments have demonstrated that the immune system is a target following exposure to a diverse group of xenobiotics including ultraviolet radiation, chemical pollutants, therapeutics, and recreational drugs. There is a well-established cause and effect relationship between suppression of the immune response and reduced resistance to infections and certain types of neoplasia. In humans, mild-to-moderate suppression of the immune response is linked to reduced resistance to common community-acquired infections, whereas opportunistic infections, which are very rare in the general population, are common in individuals with severe suppression. Xenobiotic exposure may also result in unintended stimulation of immune function. Although a cause and effect relationship between unintended stimulation of the immune response and adverse consequences has yet to be established, evidence does suggest that hypersensitivity, autoimmunity, and pathological inflammation may be exacerbated in susceptible populations exposed to certain xenobiotics. Xenobiotics can act as allergens and elicit hypersensitivity responses, or they can modulate hypersensitivity responses to other allergens such as pollen or dust mite by acting as adjuvants, enhancing the development or expression of hypersensitivity. Allergic contact dermatitis, allergic rhinitis, and asthma are the most commonly encountered types of hypersensitivity reactions resulting from chemical exposure. The immunologic effectors and mechanisms involved in autoimmune reactions are the same as those associated with responses to foreign antigens; however, the reactions are directed against the host's own cells. Thus, chemicals that induce immune suppression, nonspecific immunostimulation, or hypersensitivity may also impact autoimmunity. Risk assessment for immunotoxicity should be performed using the same approaches and principles for other noncancer effects. However, since xenobiotics may have effects on more than one aspect of immune function, immunotoxicity data should be evaluated separately for evidence of suppression, stimulation, hypersensitivity, and autoimmunity.

Contact allergy induced by bisphenol A diglycidyl ether leachables from aluminium tubes for pharmaceutical use

BACKGROUND

Aluminium tubes for pharmaceutical use are internally lacquered with epoxy resins (ER) based on bisphenol A diglycidyl ether (BADGE). Recently, it was shown that remnants of ER polymerization like BADGE are extractable from epoxy-based coatings of commercially available tubes and may leach into semi-solid drug preparations. We aimed to evaluate the safety of BADGE-contaminated macrogol ointments in individuals sensitized to ER based on BADGE by use tests.

METHODS

Repeated open application testing (ROAT) in 11 patients sensitized to ER based on BADGE with BADGE in macrogol ointments (3 mg/kg; 30 mg/kg, equivalent to BADGE concentration determined in macrogol ointment after storage in a commercially available tube; 300 mg/kg).

RESULTS

The 30 mg/kg BADGE ointment elicited reactions in three patients, and another three patients reacted to 300 mg/kg BADGE ointment. No reactions to the vehicle control and 3 mg/kg BADGE were observed.

CONCLUSIONS

Elevated BADGE concentrations in ER-coated aluminium tubes pose a risk of developing contact dermatitis to patients sensitized to ER based on BADGE. Quality standards are deemed necessary for the production of ER-coated aluminium tubes intended for pharmaceutical use and should consider the results of the present ROAT study.

Difficulties in using Material Safety Data Sheets to analyse occupational exposures to contact allergens

BACKGROUND

Information on the occurrence of contact allergens and irritants is crucial for the diagnosis of occupational contact dermatitis. Material Safety Data Sheets (MSDS) are important sources of information concerning exposures in the workplace.

OBJECTIVE

From a medical viewpoint, to evaluate the information available from MSDSs, and to ascertain whether MSDS are easy to obtain, whether they serve their purpose, and whether they provide sufficient information regarding allergens to enable correct diagnosis.

METHODS

MSDS and ingredients labelling were collected from consecutive patients and reviewed. If it was suspected that the MSDS were incomplete, the manufacturer, supplier, salesperson or workplace was contacted to gather more information.

RESULTS

Twenty-five per cent (79/316) of patients provided material for the exposure assessment. One or more shortcomings were found in 18.6% (137/738) of the MSDS. The most frequent shortcoming was 'Missing R43/H317 while known contact allergen was present', which was observed in 63.1% (84/137). Other shortcomings were 'Names of preservatives not included in section 3 despite containing preservatives', in 48.9% (67/137), and 'Nothing about allergy in sections 2, 3, 11, 15 or 16 in the MSDS despite the content of allergens', in 20.4% (28/137). The information retrieved led to additional testing of 21 patients.

CONCLUSION

Systematic exposure assessment is time-consuming. The main shortcomings are errors/omissions in the MSDS.

Occupational irritant contact dermatitis diagnosed by analysis of contact irritants and allergens in the work environment

BACKGROUND

Irritant contact dermatitis (ICD) is a common diagnosis in patients with occupational contact dermatitis (OCD). Studies are lacking on the usefulness of material safety data sheets (MSDSs) in making the diagnosis of ICD.

OBJECTIVE

To characterize irritant exposures leading to the diagnosis of occupational ICD (OICD), and to evaluate the occurrence of concomitant exposures to contact allergens.

METHODS

We included 316 patients with suspected occupational hand dermatitis, referred to the Department of Dermato-Allergology, Copenhagen University Hospital Gentofte, Denmark during January 2010-August 2011, in a programme consisting of a clinical examination, exposure assessment, and extensive patch/prick testing.

RESULTS

OCD was diagnosed in 228 patients. Of these patients, 118 were diagnosed with OICD. The main irritant exposures identified were wet work (n = 64), gloves (n = 45), mechanical traumas (n = 19), and oils (n = 15). Exposure to specific irritant chemicals was found in 9 patients, and was identified from MSDSs/ingredients labelling in 8 of these patients. Review of MSDSs and ingredients labelling showed that 41 patients were exposed to 41 moderate to potent contact allergens, and 18 patients were exposed to 25 weak workplace contact allergens.

CONCLUSION

In the present study, the systematic exposure assessment did not reveal any new irritants. MSDSs have a limited role in the investigation of ICD.

The combined diagnosis of allergic and irritant contact dermatitis in a retrospective cohort of 1000 consecutive patients with occupational contact dermatitis

BACKGROUND

The diagnosis of combined allergic and irritant contact dermatitis is an accepted subdiagnosis for hand dermatitis, and it is often considered in a patient with contact dermatitis, a positive and relevant patch test result, and wet work exposure. We therefore hypothesize that it is arbitrary for wet work exposure to be taken into consideration in a patient with newly diagnosed relevant contact allergy. Furthermore, an overestimation of the diagnosis will probably occur if the criteria for wet work exposure are applied correctly, as many occupations have an element of wet work.

OBJECTIVES

To find the statistically expected number of combined allergic and irritant contact dermatitis cases in 1000 patients, and to evaluate the diagnostic criteria for the diagnosis.

METHODS

One thousand consecutive patients with occupational contact dermatitis from a hospital unit in Denmark were assessed.

RESULTS

The expected number of cases with the diagnosis of combined allergic and irritant contact dermatitis was 0.33%, as compared with the observed number of 6.4%. Females occupied in wet occupations were often diagnosed with combined allergic and irritant contact dermatitis (p < 0.005).

CONCLUSION

The diagnosis of combined allergic and irritant contact dermatitis should be used critically to avoid misclassification, and possible criteria for the diagnosis are proposed.

Consideration of criteria required for assignment of a (skin) sensitiser a substance of very high concern (SVHC) under the REACH regulation

The identification, characterisation, risk assessment and risk management of materials that cause allergic sensitisation is an important requirement for human health protection. It has been proposed that for some chemical and protein allergens, and in particular for those that cause sensitisation of the respiratory tract (associated with occupational asthma), it may be appropriate to regard them as Substances of Very High Concern (SVHC) under the provisions of REACH (Registration, Evaluation, Authorisation and restriction of CHemicals). We have argued previously that categorisation of sensitising agents as SVHC should be used only in exceptional circumstances. In the present article, the subject of SVHC is addressed from another perspective. Here the information that would be required to provide a compelling case for categorisation of a skin sensitising substance as a SVHC is considered. Three skin sensitising chemicals have been identified to serve as working examples. These are chromate, a potent contact allergen, and the skin sensitisers formaldehyde and isoeugenol. The key criterion influencing the decision regarding a skin sensitiser being categorised as SVHC is the extent to which impacts on the quality of life are reversible. Consequently, SVHC categorisation for skin sensitising chemicals should be used only in exceptional circumstances.