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BACKGROUND: Contact allergy to oxidized (ox.) linalool and ox. limonene has been reported to have a high prevalence, raising the question of inclusion into the baseline series. However, several important issues should be clarified and further investigated before inclusion can be warranted.OBJECTIVES: To report the trends of ox. terpenes allergy in patients with dermatitis, features of the patch test reactions, and clinical characteristics of the patients.METHODS: A retrospective analysis of 5773 patients was performed. All patients were patch tested with baseline series, individual ingredients of fragrance mix I and II, ox. linalool, and ox. limonene from 2013 to 2020.RESULTS: The prevalence rates of contact allergy to ox. linalool and ox. limonene were 7.0% and 5.1%, respectively. Significantly increasing trends of contact allergy were observed. More than 95% of contact allergy cases were identified on Day 3/4. Patients with contact allergy to ox. linalool and ox. limonene were significantly younger than those with contact allergy to other fragrances and were predominantly female. Strong reactions were associated with older age and multiple fragrance allergies.CONCLUSIONS: Contact allergy to ox. linalool and ox. limonene is becoming increasingly important, and findings show intriguing features. More studies concerning the clinical relevance before recommending these substances for screening are required. (Less)

Background: Polyaminopropyl biguanide (INCI name) and polyhexamethylene biguanide (PHMB) are polymeric biguanides. PHMB is a broad-spectrum antimicrobial substance used as a preservative in many products. Due to our limited knowledge on PHMB contact allergy frequency and the fact that cases of allergic contact dermatitis to PHMB might be missed, we have included PHMB as a screening allergen since 2016. Objective: To report the prevalence of positive patch-test reactions to PHMB as a screening allergen in patients with suspected allergic contact dermatitis. Methods: A retrospective analysis of 1760 patch tested patients from July 2016 to December 2018 was performed. Polyaminopropyl biguanide 2.0% aqua was included in the extended Malmo baseline series during the study period. Results: Of all patients, 1204 (68.4%) were female. Positive patch-test reactions were reported in 19 patients (1.1%). The most common sites of lesions were face, head, and neck (52.6%). There was a significant correlation between concomitant reactions to PHMB and other cosmetic-related allergens. Conclusion: The prevalence of positive reactions to PHMB was higher than that previously reported. Patch testing with PHMB should be performed in patient with dermatitis who have lesions on the face, head, and neck. (Less)

Background: Isobornyl acrylate (IBOA) has recently been identified as one sensitizer in the FreeStyle Libre glucose sensor. Analyses with gas chromatography-mass spectrometry (GC-MS) have indicated the presence of N,N-dimethylacrylamide (DMAA) in the sensor. Material and methods: Seven patients were referred for patch testing after developing skin reactions when using FreeStyle Libre. All patients were patch tested with IBOA and DMAA. Two patients were tested with adhesive patches that had been removed from the sensors “as is,” and two patients were tested with acetone extracts of materials from the sensor. The extracts were analysed with GC-MS. Results: Six patients reacted to both IBOA and DMAA, and one patient reacted only to DMAA. Positive reactions were also observed in both patients tested with the adhesive patch "as is". One patient reacted to both an extract of the adhesive patch and an extract of the sensor itself. When analysed with GC-MS, IBOA was found in both extracts and DMAA was found in the extract of the sensor. Conclusion: Both IBOA and DMAA may be present in adhesives used in medical devices such as glucose sensors or insulin pumps, and should be patch tested when suspected contact allergic reactions to these products are investigated. (Less)

Background: The textile dye mix (TDM) 6.6% pet. contains Disperse Blue (DB) 35, Disperse Yellow 3, Disperse Orange (DO) 1 and 3, Disperse Red 1 and 17, and DB 106 and 124. The most frequent allergen in TDM-positive patients is DO 3. Around 85% of p-phenylenediamine (PPD)-allergic dermatitis patients have shown positive patch test reactions to DO 3. There has been a discussion to exclude DO 3 from TDM 6.6% because of frequent, strong reactions to TDM 6.6% and PPD. Objectives: To study if DO 3 can be omitted from a TDM. Methods: Patch tests were performed on 2250 dermatitis patients with TDM 6.6%, TDM 5.6% pet., TDM 7.0% pet., and PPD 1.0% pet.; 122 patients were also patch tested with DO 3 1.0% pet. Results: Among the 2250 patients patch tested, contact allergy prevalence to TDM 6.6% was 2.4%, to TDM 5.6% 1.8%, and to TDM 7.0% 2.0%. Of the 54 TDM 6.6%-positive patients, 55.6% reacted to PPD; as much as 42.2% of PPD-allergic women and 50% of PPD-allergic men reacted to TDM 6.6%. Of the 17 DO 3-positive patients, 94.1% showed a positive reaction to PPD. Conclusion: Results indicate that DO 3 can probably be omitted from TDM, but patch testing with TDM 6.6%, TDM 7.0%, DO 3 1.0%, and PPD 1.0% simultaneously is needed to finally decide whether it is possible or not. (Less)

SummaryBackground Fragrance mix I (FM I) and fragrance mix II (FM II) are included in the European baseline series as screening substances for fragrance contact allergy. Objectives To investigate the frequency of allergic reactions to FM I, FM II and their ingredients in consecutively patch tested patients. Materials and methods A retrospective analysis of data from 4430 patients patch tested between 2009 and 2015 was performed. Results Of the patients, 6.5% were FM I-positive and 3.2% were FM II-positive. Forty-five per cent of FM I-positive patients did not have positive reactions to FM I ingredients. Thirty-five per cent of those who were FM II-positive did not have positive reactions to FM II ingredients. Twenty-seven per cent of those with positive reactions to one or more of the FM I ingredients were FM I-negative, and 36% of those who had positive reactions to one or more of the FM II ingredients were FM II-negative. The allergens with the highest pick-up rates were Evernia prunastri (1.8%), cinnamal (1.3%), citral (1.2%), and hydroxyisohexyl 3-cyclohexene carboxaldehyde (1.2%). Significant differences were observed in the proportions of positive reactions to FM I, FM II, eugenol, isoeugenol, and farnesol when results from patch testing with materials from different suppliers were compared. Conclusions There is a risk of missing fragrance contact allergy when testing with only the fragrance mixes is performed. The use of preparations from different suppliers may affect the patch test results.

Background: In 2001, the EU nickel directive was introduced to prevent contact allergy to nickel. Contact allergy to palladium and/or cobalt is often seen together with contact allergy to nickel. Objectives: To compare the contact allergy prevalence of nickel, palladium, and cobalt allergy before and after the introduction of the EU nickel directive in consecutive patients with dermatitis. Methods: A retrospective analysis of patch test results from 1995–2016 was performed (n = 18 264). Chi-square tests were used to examine trends for nickel, palladium, and cobalt across test years. Logistic regression was used for associations. Results: The prevalence of nickel allergy decreased significantly in the youngest age group (6–30 years) for both female and male patients from 1995–1999 to 2012–2016: females: 33.4% to 19.1% (P

Background: Contact allergies to the preservatives formaldehyde and methylchloroisothiazolinone (MCI)/methylisothiazolinone (MI) have been reported to appear together at a statistically significant level. Recently, revisions concerning the patch test preparations of MCI/MI, MI and formaldehyde have been recommended for the European baseline series. Aim: To investigate (i) the number of concomitant contact allergies to the preservatives, (ii) the number of concomitant contact allergies to the preservatives and the fragrance mixes (FM I and FM II) and (iii) gender differences. Methods: Patients tested with the Swedish baseline series during the period 2012-2014 at the Department of Occupational and Environmental Dermatology in Malmo, Sweden were investigated. Results: 2165 patients were patch tested with the baseline series (34% males and 66% females). Contact allergies to formaldehyde and MCI/MI and/or MI were significantly associated (p (Less)

Background: Five workers from a plant manufacturing concrete wall panels and beams were referred to our department because of suspected occupational dermatitis. When patch tested, 3 workers reacted to potassium dichromate. Four workers reacted to ethylenediamine dihydrochloride, without any obvious exposure. Owing to the high proportion of workers with recent-onset skin disease, an investigation of all workers at the plant was initiated. Objectives: To investigate the prevalence of occupational dermatitis and contact allergy in the workers at the plant. Methods: All 24 workers at the plant underwent a clinical investigation and were patch tested. Results: Four cases of allergic occupational contact dermatitis and 3 cases of irritant occupational contact dermatitis were diagnosed. Contact allergy to potassium dichromate was found in 4 workers. All 4 also reacted to ethylenediamine dihydrochloride and/or amines that were present as additives in the cement. Conclusions: Chromate contact allergy can still be found in concrete workers, despite the legislation regulating the amount of hexavalent chromium (chromate) in cement. Occupational contact allergy to amines can be found in workers exposed to cement and concrete, so amines should be tested in these workers.

In rubber materials, both natural rubber and synthetic rubber, several different contact allergenic chemicals are added to the batch before vulcanization. These compounds are relevant for investigation of rubber allergy of workers in rubber factories. The number of workers in the rubber industry has declined, owing to increased automation of the process; however, the number of users of rubber products, such as rubber gloves, is increasing. Furthermore, users of finished rubber products are exposed to allergens other than those affecting workers in rubber factories because of chemical reactions during vulcanization between different additives, altering their structures. Our experience with thiuram mono- and disulfides is that during vulcanization, monosulfides are formed from disulfides. We have also seen that in rubber vulcanized with both thiurams and mercaptobenzothiazole compounds, chemicals are formed that contain both thiocarbamate and a mercaptobenzothiazole structure. Two examples of this are dimethylthiocarbamylbenzothiazole sulfide (DMTBS) and diethylthiocarbamylbenzothiazole sulfide (DETBS). The latter is a commercial accelerator with the name Ethylac. In an earlier study in which we patch tested 24 volunteers with a known allergy to thiuram mix and/or mercapto mix, we observed positive reactions to DMTBS (1% petrolatum) and/or DETBS (1% petrolatum) in 20 subjects. So far we have seen positive reactions to either DMTBS or DETBS in two patients who were investigated because of their dermatitis related to the rubber in their swimming goggles. Chemical analysis of the swimming goggles showed them to contain DMTBS and DETBS, respectively. Furthermore, several patients in the Netherlands and Belgium with allergy to their shoes were found to be allergic to DMTBS. Chemical analysis of these shoes has been performed and DMTBS was identified in the rubber lining. The allergy to DMTBS is an example of how a powerful allergen can be formed during vulcanization as a result of chemical reactions between well-known haptens. It also illustrates that chemical investigations of patients' rubber items can uncover the presence of allergens that were not added during manufacturing and therefore never show up in declarations from the producers. (Less)

Formaldehyde is a well-known contact sensitizer. Formaldehyde releasers are widely used preservatives in cosmetics.

Formaldehyde is a well-known contact sensitizer. Formaldehyde releasers are widely used preservatives in skincare products. It has been found that formaldehyde at concentrations allowed by the European Cosmetics Directive can cause allergic contact dermatitis. However, we still lack information on whether formaldehyde at low concentrations affects dermatitis in formaldehyde-allergic individuals.To study the effects of low concentrations of formaldehyde on irritant contact dermatitis in formaldehyde-allergic individuals.Fifteen formaldehyde-allergic individuals and a control group of 12 individuals without contact allergy to formaldehyde and formaldehyde releasers were included in the study. The individuals performed the repeated open application test (ROAT) during 4 weeks with four different moisturizers releasing formaldehyde in concentrations that had been determined as 40, 20-40, 2·5-10 and 0 p.p.m. by the chromotropic acid (CA) spot test. Dimethyloldimethylhydantoin was used as a formaldehyde releaser in the moisturizers. The ROAT was performed on areas of experimentally induced sodium lauryl sulfate dermatitis. The study was double blind, controlled and randomized.Nine of the 15 formaldehyde-allergic individuals had reappearance or worsening of dermatitis on the areas that were treated with moisturizers containing formaldehyde. No such reactions were observed in the control group (P 0·001) or for the moisturizers without formaldehyde in the formaldehyde-allergic individuals (P 0·001).Our results demonstrate that the low concentrations of formaldehyde often found in skincare products by the CA method are sufficient to worsen an existing dermatitis in formaldehyde-allergic individuals.

Background: Historically, allergic contact dermatitis caused by hexavalent chromium [Cr(VI)] in cement was the most common cause of invalidity attributable to skin disease in Sweden. Since the legislation to reduce Cr(VI) in cement was introduced in 1989, we rarely see allergic contact dermatitis caused by cement. Objectives: To examine the frequency of contact allergy to Cr(VI) in southern Sweden in 2005-2014. Methods: We investigated the occurrence of positive reactions to potassium dichromate 0.5% pet. in consecutively tested dermatitis patients, and compared the occurrence of atopic dermatitis, localization of dermatitis and simultaneous positive reactions to cobalt chloride and nickel sulfate in the Cr(VI)-positive patients with those in a group of patients with a similar age and sex distribution. Results: In total, 6482 patients were tested, and 233 Cr(VI)-allergic individuals were found (3.6%). A significantly higher proportion of atopic dermatitis was found among Cr(VI)-allergic patients, and a significantly higher share of foot dermatitis was found among Cr(VI)-allergic women, than among controls. Cr(VI) allergy was less likely when both nickel allergy and cobalt allergy were present. Conclusion: A relatively high frequency of contact allergy to Cr(VI) was found. The cause has shifted from cement exposure to other exposures, probably mainly leather. (Less)

Summary Background Vulcanization of rubber changes its allergen pattern. Objectives To estimate the contact allergic reactivity profile of users of finished rubber products. Methods Twenty-four patients with known contact allergy to rubber accelerators were patch tested with 21 compounds found in chemical analyses of vulcanized rubber products. No diphenylguanidine, p-phenylenediamine antioxidants or thioureas were included in the study. Results Thiuram monosulfides formed during vulcanization showed generally stronger test reactions than the corresponding thiuram disulfides. We also obtained more positive thiuram reactions to the monosulfides than to the disulfides. A positive reaction to a dithiocarbamate was accompanied by a positive reaction to the corresponding thiuram, except for 1 patient. The nitrogen substituents showed only minor differences between the methyl, ethyl and pentamethylene groups, but the butyl derivatives gave, in most cases, a negative response. Dialkylthiocarbamyl benzothiazole sulfides, formed between thiurams and mercaptobenzothiazoles during vulcanization, showed strong test reactions in almost all patients who were sensitive to dithiocarbamates, thiurams, or mercaptobenzothiazoles. Conclusions We found thiuram monosulfides to be better markers of thiuram sensitivity than the corresponding disulfides or dithiocarbamates. Surprisingly, the dialkylthiocarbamyl benzothiazole sulfides were good markers of both thiuram and mercaptobenzothiazole sensitivity. This is an unexpected finding that needs to be confirmed in a larger study.

Background An increased frequency of occupational contact hand dermatitis among surgical operating theatre personnel has been noticed. Objectives To evaluate patients with occupational contact dermatitis caused by their rubber gloves, and to describe a method for analysing the content of the allergens in the gloves. Materials and methods Patch tests were performed with the baseline series, a rubber chemical series, and the patients' own gloves. A method for analysing 1,3-diphenylguanidine (DPG) and cetylpyridinium chloride in the gloves was developed. Results Contact allergy to thiuram mix was found in 8 of 16 patients, whereas 12 of 16 patients reacted to DPG. In 7 of 8 patients, contact allergy to cetylpyridinium chloride was found. In the patients' gloves, cetylpyridinium chloride and DPG were detected at higher concentrations on the inside of the gloves than on the outside. Most patients had worked for decades in their present occupations, but their hand dermatitis had only been present for months. Conclusion Contact allergy to DPG in gloves has been disputed, but, in this study, we were able to confirm the presence of DPG and cetylpyridinium chloride in the causative gloves by using a modified method for the analysis. The presence of these chemicals in gloves caused an increase in occupational contact dermatitis in surgical operating theatre personnel. (Less)

The preservative methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) is a well-known sensitiser and present in most baseline series since at least 20 years. The proportions of MCI/MI are 3:1. MI alone has been used as a preservative in occupational and household products, and cosmetics since less than 10 years. MCI/MI tested at 100 ppm fails to detect a significant percentage of contact-allergic reactions to MI. Our aim was to investigate whether a separate test preparation with MI picks up additional cases of contact allergy to MI not detected with MCI/MI 200 ppm. MI was inserted into the baseline series of the Malmo clinic in 2003 starting at 475 ppm, then 900 ppm, then 1,000 ppm, 1,500 ppm and finally 2,000 ppm. In 5,881 consecutively tested dermatitis patients the contact allergy rate for MI varied between 0.5 and 6.5%, with a marked increase in recent years. The contact allergy rate to MI 2,000 ppm alone, not traced by MCI/MI 200 ppm, varied between 0 and 1.9%. In conclusion, due to the increase of contact allergy to MI not traced by MCI/MI 200 ppm, MI in water at 2,000 ppm should be tested in a baseline series. Independent of patch test technique a dose of 60 µg/cm should not be exceeded to avoid adverse reactions and particularly patch test sensitisation. (Less)

Due to the clinical findings in a single patient's case, formaldehyde was suspected to be present in clinically relevant levels in reusable protective gloves. Therefore, 9 types of gloves were investigated with the semi-quantitative chromotropic acid method. It was found that 6/9 gloves emitted some formaldehyde and that 4/9 gloves emitted > or =40 microg of formaldehyde. Most of the formaldehyde was found on the inside of the gloves. To get an indication of the clinical relevance, a comparison with a protective cream declared to contain the formaldehyde-releasing agent diazolidinyl urea was performed by comparing areas of gloves with areas of cream layers with thickness 1-2 mg/cm(2). It was found that the amounts of formaldehyde emitted from the gloves might be in the same range as emitted from a layer of cream.

An outbreak of suspected contact dermatitis among subway construction workers was suspected to be due to a new bisphenol A/F-based epoxy resin system (ERS). The construction workers used ERSs during the insertion of iron bars into concrete walls. The objective of the study was to determine the components (if any) of the ERS responsible for the contact allergy. Patch testing was performed on 20 of the 22 construction workers who had had contact with the ERS, and to the various subcomponents of component A on 5 of the 7 who reacted to this component. 9 patients (9/22, 40.9%) had clinical symptoms and signs of suspected contact dermatitis at presentation. 7 of these 9, but none of the 11 asymptomatic individuals, were positive to component A, while all were negative to component B. Of the 5 cases receiving further patch testing, all reacted to m-xylylene diamine, 4 to 1,6-hexanediol diglycidyl ether, 3 to epoxy resins of the bisphenol F-type and trimethylolpropane triglycidyl ether 0.25% petrolatum, and only 1 to epoxy resins of the bisphenol A-type. Contact allergy to ERSs may involve hardeners and diluents as well as resins, and patch testing for reaction to all components should be performed.

The currently used patch test concentration of formaldehyde (1.0% aqua; 0.30 mg/cm(2) ) has been shown to fail to detect ˜ 50% of contact allergies to formaldehyde.

Over a short period of time, there was an outbreak of work-related skin lesions among workers at a company producing flooring laminate boards, after the introduction of a water-repellent lacquer based on diphenylmethane-4,4'-diisocyanate (MDI). In 5 workers, patch testing was performed with a standard series, an isocyanate series and work-environmental products when indicated. 3 of the workers were tested with the lacquer, and contact allergy was found with concurrent reactions to 4,4'-diaminodiphenylmethane (MDA). 1 of the 3 workers also showed a simultaneous reaction to MDI, whereas 1 showed a positive reaction to dicyclohexylmethane-4,4'-diisocyanate (HMDI). Of the 2 individuals not tested with the lacquer, 1 reacted to both MDI and MDA, whereas the other reacted to a soap used at work. In 3 of 4 cases, the isocyanate reactions appeared after D3. Occupational contact with isocyanates should not exclusively be focused upon respiratory hazards, as this report shows that skin contamination probably increases the risk of developing contact allergy to isocyanates and isocyanate-related substances. When aiming at diagnosing contact allergy to isocyanates, it is desirable to perform a late reading, as positive reactions appear late. MDA appears to be a good marker for isocyanate hypersensitivity.

In this study, the sensitizing capacities of the 3 main low-molecular-weight isomers of epoxy resins based on diglycidyl ether of biphenol F (DGEBF) were investigated in a guinea pig maximization test (GPMT). The isomers are p,p'-DGEBF, o,p'-DGEBF, and o,o'-DGEBF. The sensitization capacities were compared to diglycidyl ether of bisphenol A (DGEBA), which is the main constituent in the most common epoxy resin. The cross-reaction pattern between all 4 compounds was also investigated. It was found that all 3 DGEBF isomers were potent sensitizers. It was also found that p,p'-DGEBF, o,p'-DGEBF, and DGEBA cross-reacted with one another, and that animals induced with o,o'-DGEBF reacted significantly only to o,p'-DGEBF, but not to the other 2 DGEBF isomers or DGEBA.

A golfer presented with facial and hand eczema. He had exacerbations of his hand eczema prior to golf tournaments. Being an authorized golf club repairman, he had been working with a two-part glue containing an epoxy resin (ER) based on diglycidyl ether of bisphenol A (DGEBA) and the hardener diethylenetriamine (DETA) for approximately 4 years before he developed any skin problems. He was patch-tested with the standard, which contains an ER based on DGEBA (DGEBA-R), epoxy (containing DETA), and rubber glove series and had positive reactions to DGEBA-R only. Other work materials (a latex glove, a golf glove made of leather, and part of the handle of his own golf club "as is" and in a methyl tert-butyl ether extract) were tested, with negative results. Allergic contact dermatitis from ER affects the skin by direct contact; the dermatitis is usually localized to the hands and forearms. If the face and eyelids are involved, the dermatitis may be due to exposure to airborne hardeners or reactive diluents, exposure to airborne dust from residual monomers, or ectopic allergic reactions. Our repairman had sandpapered an old glued surface, which may have led to possible airborne dust formation, thus explaining the facial eczema. Therefore, a worker with contact allergy to ER may continue working provided the skin is protected from contamination.

BACKGROUND: The currently used patch test concentration for formaldehyde is 1.0% (wt/vol) in water. However, clinical experience and previous studies suggest that 1.0% might be insufficient for detecting an optimized number of clinically relevant cases of contact allergy to formaldehyde. OBJECTIVES: To validate earlier patch test results for comparison of 1% (wt/vol) and 2% (wt/vol) formaldehyde in water, and to investigate co-reactivity with quaternium-15. MATERIALS AND METHODS: In 12 dermatology clinics, 3591 patients were routinely patch tested simultaneously with 2.0% (wt/vol) (0.60 mg/cm(2)) and 1.0% (wt/vol) (0.30 mg/cm(2)) formaldehyde. Micropipettes were used for delivering the exact dosage of the allergen. RESULTS: Significantly more patients reacted to 2.0% formaldehyde than to 1.0% (3.4% versus 1.8%, p < 0.001). Overall, there were no sex differences between those reacting positively to 2.0% and 1.0%. Of 25 quaternium-15-positive patients, 4 (0.1%) reacted positively without reacting to formaldehyde. CONCLUSION: On the basis of the results of this multicentre study, as well as of previous studies, it can be suggested that 2.0% (wt/vol) in water formaldehyde should be used in routine patch testing in the baseline series.

Background: It has been found that patch testing with 15μl formaldehyde 2.0% aq detects twice more allergies than testing with 1.0%. The clinical relevance of positive patch test reactions is often difficult to determine. Use tests are simple to do and help to evaluate the significance of patch test results. Objectives: To study the clinical relevance of contact allergy to formaldehyde detected by 2.0% (0.60 mg/cm²) but not by 1.0%. Patients/Methods: 18 patients positive to formaldehyde 2.0% but negative to 1.0% and a control group of 19 dermatitis patients without allergy to parabens, formaldehyde and formaldehyde releasers were included in the study. Formaldehyde 2000 ppm, the maximum concentration permitted in leave-on cosmetics according to the EU Cosmetics Directive, was added to a batch of a moisturiser preserved with parabens. The same batch without formaldehyde served as control. The study was double-blinded and randomised. The patients were provided with both moisturisers and instructed to apply one of them twice a day on a marked-out 5×5 cm area on the inside of one upper arm and the other moisturiser on the other arm. Reading of the test sites was done once a week for a maximum of 4 weeks. Results: In the control group there were no allergic reactions to any of the moisturisers. 9 of the 17 formaldehyde-allergic patients reacted with an allergic reaction to the moisturiser which contained formaldehyde (p

Keywords: epoxy resin; diglycidyl ether of bisphenol A; diglycidyl ether of bisphenol F; epoxy novolac resin; allergic contact dermatitis; occupational

Our clinical experience has suggested that the presently recommended patch-test concentration (1.0%) for formaldehyde in the baseline series might be too low. Therefore, consecutively patch-tested dermatitis patients were tested simultaneously with formaldehyde 1.0% and 2.0% (w/v) in aqua. Formaldehyde 1.0% and 2.0% were applied with a micro-pipette (15 microl) to filter paper discs in Finn Chambers (0.30 mg/cm(2) and 0.60 mg/cm(2), respectively). A total of 1397 patients with dermatitis were patch-tested. In all, 68 (4.9%) patients reacted positively to formaldehyde; 37 reacted only to 2.0%, 29 reacted to both concentrations, and 2 reacted only to 1.0%. Significantly more patients were thus diagnosed with contact allergy to formaldehyde 2.0% compared with 1.0% (p < 0.001). We detected 0.1%, 0.4%, and 29.6% irritant reactions to 1.0%, 2.0%, and 3.0% formaldehyde, respectively. We conclude that, with an optimized patch-test technique, doubling the dose per area detects significantly more contact allergies to formaldehyde, but an even higher test concentration causes too many irritant reactions to be usable.

BACKGROUND: Simultaneous contact allergies to the reactive diluent phenyl glycidyl ether (PGE) and epoxy resins based on diglycidyl ether of bisphenol A (DGEBA) or epoxy resins of the bisphenol F-type have been reported. The latter epoxy resins contain three isomers of diglycidyl ether of bisphenol F (DGEBF). PGE, DGEBA, and DGEBF are chemically similar with respect to the reactive glycidyl group and an aromatic ring, making cross-reactivity one of the possible explanations to simultaneous reactions. AIM: To investigate the sensitizing capacity of PGE and the cross-reactivity of PGE versus the epoxy resin monomers DGEBA and the three DGEBF monomers and vice versa. METHOD: The guinea-pig maximization test. RESULTS: PGE is a strong sensitizer. Induction with DGEBA resulted in a statistically significant number of animals reacting to PGE, but when induced with PGE, the animals did not react significantly to DGEBA. CONCLUSIONS: When the results are applied to humans, it can be assumed that patients sensitized primarily to DGEBA react to PGE, but when sensitized exclusively to PGE, they do not react to DGEBA. Both reactive diluents and epoxy resins should be tested when contact allergy to epoxy resin systems are suspected. (Less)

BACKGROUND: Simultaneous contact allergies to epoxy resins based on diglycidyl ether of bisphenol A (DGEBA-R) or epoxy resins of the bisphenol F-type and the reactive diluent phenyl glycidyl ether (PGE) have been reported. The reason might be cross-reactivity, exposure to an epoxy resin system with PGE as a component, or contamination by PGE in the epoxy resin. AIMS: To study contamination by PGE, 20 commercial epoxy resins were analysed for the presence of PGE. To study contact allergy to PGE and its relation to epoxy resins by inserting PGE in the standard series. RESULTS: Among 2227 patients, 7 reacted to PGE. Of 23 (30%) patients, 7 with contact allergy to DGEBA-R and 7/19 (37%) with contact allergy to an epoxy resin of the bisphenol F-type reacted to PGE. All 7 patients with contact allergy to PGE reacted both to the DGEBA-R and to the epoxy resin of the bisphenol F-type. PGE was found in 90% of the investigated resins. The amounts of PGE ranged between 0.004% w/w and 0.18% w/w. CONCLUSION: Most probably, the presence of PGE as a contaminant in epoxy resins is of minor importance for the sensitization, but possibly the contamination of PGE might elicit contact dermatitis in individuals with a high reactivity to PGE. (Less)

Diglycidyl ether of bisphenol A (DGEBA) is the monomer and most important contact allergen in epoxy resin(s) based on bisphenol A (DGEBA-R). Both thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC) methods are available for the analysis of products containing DGEBA-R. With respect to detection and quantification, epoxy resins of the bisphenol F-type, i.e. epoxy resins containing the isomers of diglycidyl ethers of bisphenol F (DGEBF), are not as well investigated as DGEBA-R. The isomers of DGEBF are p,p'-DGEBF, o,p'-DGEBF and o,o'-DGEBF. Both p,p'-DGEBF and o,p'-DGEBF have been shown to be contact allergens in humans, and all 3 isomers are sensitizers in the guinea pig maximization test. We aimed (i). to develop HPLC methods for separation and purification of the individual DGEBF isomers, (ii). to detect and quantify the DGEBF isomers in epoxy resins of the bisphenol F-type and (iii). to evaluate and develop the TLC as a method for the detection of the DGEBF monomers. We found the total content of the DGEBF isomers in the investigated epoxy resins of the bisphenol F-type to vary from 17.0 to 81.7% w/w. Some of them also contained 0.1-2.4% w/w DGEBA. The HPLC method showed a sensitivity that was 2000-20 000x higher than that obtained with the TLC method for the DGEBF monomers. We concluded that the range of the DGEBF isomer content in epoxy resins of the bisphenol F-type is approximately the same as the monomer content in liquid compared to solid DGEBA-R. The relevance of contact allergy to DGEBA-R can remain unrecognized if the suspected product is an epoxy resin of the bisphenol F-type, which is analysed with the TLC method.

Diglycidyl ether of bisphenol A (DGEBA) is the monomer and main allergen in the most common epoxy resin, DGEBA-R. Epoxy resin(s) based on bisphenol F (DGEBF-R) contains the 3 isomers of the diglycidyl ether of bisphenol F. Contact allergy to these isomers (p,p'-DGEBF, o,p'-DGEBF and o,o'-DGEBF) has not previously been described in humans. To investigate contact allergies to the DGEBF isomers in patients with contact allergy to DGEBF-R, 9 patients were patch-tested with dilution series of the isomers. All 9 were found to have contact allergy to p,p'-DGEBF and 7/9 to o,p'-DGEBF. Additionally, of 20 workers employed in epoxy-based manufacture and with contact allergy to DGEBA-R and DGEBF-R, 18 reacted to p,p'-DGEBF and 15/20 to o,p'-DGEBF. According to a guinea pig maximization test, all 3 DGEBF isomers are strong sensitizers. Still, o,o'-DGEBF elicited only 3 positive reactions in all participants.

Phenyl glycidyl ether (PGE) is an aromatic reactive diluent used in epoxy resin systems. The sensitizing capacity of PGE, as well as the cross-reactivity between PGE and the most important contact allergens in epoxy resins based on bisphenol A and bisphenol F, i.e. diglycidyl ether of bisphenol A (DGEBA) and the 3 isomers of diglycidyl ether of bisphenol F (p,p′-DGEBF, o,p′-DGEBF, and o,o′-DGEBF), were investigated in a guinea pig maximization test (GPMT). Statistical significance was calculated with one-sided Fisher’s exact test. PGE was found to be a strong sensitizer (24/24 sensitized animals, p