Identification of causative chemicals of allergic contact dermatitis using a combination of patch testing in patients and chemical analysis

3 cases of allergic contact dermatitis from industrial rubber products were investigated using a combination of patch testing in patients and chemical analysis of causative rubber products by gas chromatography (GC), GC-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). Our studies revealed N-isopropyl-N'-phenyl-p-phenylenediamine (IPPD), a typical rubber allergen, as a causative chemical in a case from a brand of heavy-duty rubber gloves and a case from a black rubber ring for car manufacture, and zinc ethylphenyldithiocarbamate (ZEPC), a dithiocarbamate (DTC)-type accelerator, as a causative chemical in a case from a brand of rubber work gloves: both IPPD and ZEPC, which showed positive patch test reactions, were confirmed in the extracts of the causative rubber products by GC, GC-MS and/or HPLC.     

Skin elicitation threshold of ethylbutyl thiourea and mercaptobenzothiazole with relative leaching from sensitizing products

We studied 3 contact sensitizers present in rubber products, ethylbutyl thiourea (EBT), 2-mercapto-benzothiazole (MBT) and 2,2-dithio-bis-benzothiazole (MBTS), to relate the amount orsensitizer eliciting allergic contact dermatitis to the quantity leaching from a product into various biological fluids: normal saline, human plasma and 3 synthetic sweat solutions of pH 5.5 to 7.5. To determine the amount of sensitizer remaining after leaching, Soxhlet extraction with acetonitrile was subsequently performed. High-performance liquid chromatography was used for chemical analysis. 12 MBT-sensitive patients were patch tested with serial dilutions of MBT and MBTS in petrolatum. A Latin Square design was used in statistical analysis of variance of the patch test results. Large amounts of thioureas leached from 2 rubber articles eliciting thiourea dermatitis, the literature suggesting that these would have been well above the elicitation threshold. Leaching of MBTS was relatively greater than MBT into most media, whereas MBT was a more potent elicitor than MBTS at equivalent concentrations. The lowest eliciting concentration of MBT in 1 subject was 0.01%. Such information should prove helpful to manufacturers in designed products that do not release allergens sufficiently to cause reactions in consumers.     

Isolation, via activity-directed fractionation, of mercaptobenzothiazole and dibenzothiazyl disulfide as 2 allergens responsible for tennis shoe dermatitis

Although contact dermatitis from shoes is common, the causative allergen is frequently not known. Reliance cannot be placed on standard screening trays because such testing can be negative when testing to shoe materials is positive. Furthermore, the relevance of positive screening tests is almost never proven by extracting that allergen from the patient's shoes. We present a case of insole dermatitis to tennis shoes in which we directly isolated the causative allergens by step-by-step patch-test monitoring of active fractions. Chromatographic separation of the active fractions led to the isolation of 2 allergens, mercaptobenzothiazole (Captax) (MBT) and its dimer, dibenzothiazyl disulfide (Altax) (DBTD). Patch tests to DBTD were noticeably more potent than those to MBT. In what might be considered an obvious case of contact sensitivity to MBT, the actual allergen is DBTD. Using this method, unknown shoe allergens can be isolated, identified, and added to the shoe test tray of potential allergens.     

Identification of causative chemicals of allergic contact dermatitis using a combination of patch testing in patients and chemical analysis Application to cases from rubber gloves

5 cases of allergic contact dermatitis from rubber gloves were investigated by our recommended procedures using a combination of patch testing in patients and chemical analysis of causative rubber products by gas chromatography (GC) and high-performance liquid chromatography (HPLC). We previously confirmed that zinc ethylphenyldithiocarbamate (ZEPC), a dithiocarbamae-type accelerator (DTC), was causative in a case of allergic contact dermatitis from rubber work gloves. Subsequently, we have clarified that DTCs such as zinc dimethyldithiocarbamate (ZDMC), zinc diethyldithiocarbamate (ZDEC) and zinc dibutyldithiocarbamate (ZDBC) and amines such as dimethylamine (DMA), diethylamine (DEA) and piperidine (PIP) were also causative in cases from surgical rubber gloves. Thus, our investigative studies revealed that, although thiurams have been taken much more notice of as allergenic compounds than their corresponding DTCs and amines, not only DTCs such as ZDMC, ZDEC, ZDBC and ZEPC, but also amines such as DMA, DEA and PIP were noteworthy causative candidates of allergic contact dermatitis from rubber gloves.     

Phosgene (chlorophenyl)hydrazones, strong sensitizers found in yellow sweaters bleached with sodium hypochlorite, defined as causative allergens for contact dermatitis by an experimental screening method in animals

12 young men developed allergic contact dermatitis from wearing yellow cotton sweaters. We attempted to identify the causative agents by an experimental screening method in animals. Guinea pigs were sensitized with an acetone extract of the sweater material, by means of the guinea pig maximization test (GPMT). Active ingredients were then separated from the extract, by step-by-step patch test screening of chromatographic fractions in the guinea pigs, and finally analyzed by gas chromatography-mass spectrometry (GC-MS). Although there were 2 allergens with important activity (1 in the fraction eluted from the silica gel column with hexane, and 1 in the methanol fraction), the present study is focussed on the fat-soluble allergens in the hexane fraction. GC-MS analysis revealed that 4 kinds of phosgene (chlorophenyl)hydrazones (PCPHs) were present in the hexane fraction. PCPHs prepared in our laboratory showed strong eliciting activities, not only in the guinea pigs sensitized with the extract, but also in a male volunteer sensitized by exposure to a yellow sweater during irritancy testing. Phosgene (2,5-dichlorophenyl)hydrazone, which was the main component among the PCPHs found in the sweater, sensitized guinea pigs even at the 1 ppm level. From these results, we conclude that PCPHs were one of the allergens responsible for the cases.     

Footwear dermatitis

We conducted a study to determine the prevalence and clinical patterns of footwear dermatitis, patch testing 50 patients with suspected footwear dermatitis and 30 controls with 22 allergens of a shoe series (Chemotechnique Diagnostics AB, Malmö. Sweden). The overall prevalence among contact dermatitis cases was 11.7%. The dorsa of the feet and toes were the commonest sites involved. 70% of patients showed sensitivity to footwear allergen(s), as opposed to 6.67% of controls. Potassium dichromate and colophony were the commonest sensitizers. Other sensitizers were the rubber accelerators 2-mefcaptobeczothiazok (MBT) and diphenylguanidine (DPG) and a dye p-aminoazobenzene. Of the 23 patients patch tested with pieces or scrapings of footwear, only 3 showed positive reactions. We recommend that there should be primary and secondary'footwear screening series to detect the responsible allergens, with the ultimate objective of providing correct nonallergenic footwear for our patients, with the help of manufacturers and research institutes.     

Allergic contact dermatitis in venous leg ulcer patients

Our aim was to determine the frequency and nature of contact sensitivity in venous leg ulcer patients in Lanarkshire. We performed patch testing with the European standard series, antimicrobials and medicaments on 200 patients referred to our leg ulcer clinics. Positive patch tests were found in 136 (68%) patients. Multiple allergies occurred in 102 (51%). The most frequent allergen groups were fragrances (30.5%), antimicrobials (19.5%), topical excipients (19.5%), rubber accelerators (13.5%) and topical corticosteroids (8%). We also found a high prevalence of positive patch tests to Intrasite gel (9.5%) and Hioxyl cream (8.5%), medicaments which are commonly used to treat leg ulcers in our area. Contact sensitivity is common in venous leg ulcer patients and has important implications for patient management. The allergens involved vary depending on local nursing practice. We suggest that all venous leg ulcer patients be patch tested with a locally relevant patch test series.     

Contact dermatitis in children

272 children up to the age of 14 years were patch tested during a 10-year period (1982–1991). 101 children (37.1%) gave positive reactions to 1 or more allergens. Of these, 54.4% (57/101), were considered relevant. The main allergens were, in order of frequency: nickel, rubber compounds, mercuric chloride, cobalt salts, thimerosal, benzoyl peroxide and fragrance mix.     

Patch testing with mixes Note on mercaptobenzothiazole mix

Mixes for patch testing conserve space and time. History and current usage of mixes are reviewed with comments on stability, concentration, consistency, use of infrequent allergens, vehicle, and ingredients of mixes. Phenomena of 'aging', 'maturity', 'balance', 'stability' and 'quenching' have been studied elsewhere for naturally occurring mixes such as aroma chemicals (fragrances and flavorings). Little is known about any such changes for mixes of chemicals made for patch test purposes. The correct concentration of mercaptobenzothiazole (MBT) for MBT mix is discussed.     

185例面部皮炎患者临床及斑贴试验结果分析

目的:测定面部皮炎患者过敏原.方法:对185例面部皮炎患者进行国际接触性皮炎研究组认定产品-瑞敏接触变应原斑贴试验.结果:斑贴试验阳性者136例(73.5%),其中常见的致敏原依次为硫酸镍(25.9%),硫柳汞(20.5%)、重铬酸钾(16.2%)、甲醛(13.5%)、对苯二胺(11.4%)、芳香混合物(10.3%)等.结论:所有面部皮炎患者均应进行斑贴试验以寻找可能致敏原.     

Occupational allergic contact dermatitis and patch test results of leather workers at two Indonesian tanneries

Background. Tannery workers are at considerable risk of developing occupational contact dermatitis. Occupational skin diseases in tannery workers in newly industrialized countries have been reported, but neither the prevalence of occupational allergic contact dermatitis nor the skin‐sensitizing agents were specifically examined in those studies. Objectives. To assess the prevalence of occupational allergic contact dermatitis in Indonesian tanneries, identify the causative allergens, and propose a tannery work series of patch test allergens. Patients/methods A cross‐sectional study in all workers at two Indonesian tanneries was performed to assess the prevalence of occupational contact dermatitis via a questionnaire‐based interview and skin examination. Workers with occupational contact dermatitis were patch tested to identify the causative allergens. Results. Occupational contact dermatitis was suspected in 77 (16%) of the 472 workers. Thirteen (3%) of these 472 workers were confirmed to have occupational allergic contact dermatitis. Potassium dichromate (9.2%), N,N‐diphenylguanidine (5.3%), benzidine (3.9%) and sodium metabisulfite (2.6%) were found to be the occupationally relevant sensitizers. Conclusions. The sensitization pattern showed some differences from the data in studies reported from other newly industrial countries. We compiled a ‘tannery work series' of allergens for patch testing. A number of these allergens may also be considered for patch testing in patients with (leather) shoe dermatitis.     

Polysensitisation in a laboratory scientist associated with allergic contact dermatitis from methylisothiazolinone in skin cleansers

Polysensitisation refers to reactivity to three or more allergens on epicutaneous patch testing, and is likely to affect a distinct subgroup of individuals with allergic contact dermatitis (ACD). Methylisothiazolinone (MIT) is an increasingly prevalent allergen, recently having been described as occurring in epidemic proportions. We report a patient with ACD to 12 allergens, including MIT, and discuss the implications of polysensitisation and the likely need for repeat patch testing in such patients if they subsequently re‐present with dermatitis.     

Contact dermatitis in children

125 children under the age of 12 years were patch tested over a period of 7 years. 60 (48%) of the children had 1 or more positive (+ve) reactions, of which 92% (55/60) were considered relevant. The most common allergens were metals (35 + ves), fragrances (24 + ves) and rubber compounds (11 + ves). 40 of the children were also tested for contact urticaria against food additives and fragrances, of whom 20 were positive (benzoic acid 14, cinnamaldehyde 12).     

European Standard Series patch test results from a contact dermatitis clinic in Israel during the 7-year period from 1998 to 2004

The results of a 7-year retrospective study (1998-2004) from patch testing with the European Standard Series (ESS) establishing the frequency of sensitization in a contact dermatitis clinic in Israel are presented. 23 allergens were patch tested on 2156 patients, 1462 females (67.8%) and 694 males (32.2%). Atopy and asthma were present in 21.9% of the patients. One or more allergic reactions were observed in 937 patients (43.5%). The highest yield of patch test positives from the 1076 positive reactions were obtained from nickel sulfate (13.9%), fragrance mix (7.1%), potassium dichromate (3.8%), Balsam of Peru (3.6%), CL+Me-isothiazolinone (3.4%) and cobalt chloride (3.4%). Allergens which produced the least amount of positive results were primin and clioquinol. Allergic contact dermatitis (ACD) was established in 32.8%, whereas occupationally related allergic (8.0) and irritant contact dermatitis (5.6%) affected a total of 13.6% of the cases studied. The most common clinical forms of dermatitis were chronic dermatitis (47.7%) followed by acute dermatitis (22.8%), and lichenification and hyperkeratosis (7.9%). The hands (30.7%), face and neck (23.9%) and extremities (11.3%) were the most frequently affected areas. Four allergens in our study differed from the top 10 allergens in Europe namely: Cl+Me-isothiazolinone, formaldehyde, 4-tert-butylphenol formaldehyde resin and sesquiterpene lactone mix reflecting an existing difference in environmental exposure. Our study is the first to provide data on the frequency of sensitization and important allergens in the aetiology of ACD in Israel. In spite of the existing differences with Europe, we conclude that ESS is an appropriate screening system for the diagnosis of ACD in Israel.     

Contact and primary irritant dermatitis of the nail unit diagnosis and treatment

Contact dermatitis of the nail unit is not rare. The most common allergens are found in nail cosmetics such as enamel, sculptured nails, and preformed plastic tips. Toluene sulfonamide formaldehyde resin, acrylates, and ethylcyanoacrylate are the most common allergens. Along with a proper clinical history focusing on nail practices, a thorough understanding of the common allergens and patch testing are necessary to diagnose contact dermatitis. A discussion of the common allergens and irritants relevant to the nail unit will be presented.     

Sesquiterpene lactone mix patch testing supplemented with dandelion extract in patients with allergic contact dermatitis, atopic dermatitis and non-allergic chronic inflammatory skin diseases

We investigated the value of patch testing with dandelion (Compositae) extract in addition to sesquiterpene lactone (SL) mix in selected patients. After we detected a case of contact erythema multiforme after patch testing with dandelion and common chickweed (Caryophyllaceae), additional testing with common chickweed extract was performed. A total of 235 adults with a mean age of 52.3 years were tested. There were 66 men and 169 women: 53 consecutive patients with allergic contact dermatitis (ACD); 43 with atopic dermatitis (AD); 90 non-atopics suffering from non-allergic chronic inflammatory skin diseases; 49 healthy volunteers. All were tested with SL mix 0.1% petrolatum (pet.) and diethyl ether extracts from Taraxacum officinale (dandelion) 0.1 and 3.0% pet. and from Stellaria media (common chickweed) 0.1 and 3% pet. A total of 14 individuals (5.9%) showed allergic reaction (AR) to at least 1 of the plant allergens, 4 (28.6%) to common chickweed extract, and 11 (78.6%) to Compositae allergens. These 11 persons made the overall prevalence of 4.7%: 8 (3.4%) were SL-positive and 3 (1.3%) reacted to dandelion extract. 5 persons (45.5%) had AD, 2 had ACD, 2 had psoriasis and 2 were healthy controls. The Compositae allergy was relevant in 8 cases (72.7%). The highest frequency of SL mix sensitivity (9.3%) was among those with AD. Half the SL mix-sensitive individuals had AD. ARs to dandelion extract were obtained only among patients with eczema. A total of 9 irritant reactions (IRs) in 9 individuals (3.8%) were recorded, 8 to SL mix and 1 to common chickweed extract 3.0% pet. No IR was recorded to dandelion extract (P = 0.007). Among those with relevant Compositae allergy, 50.0% had AR to fragrance mix and balsam of Peru (Myroxylon pereirae resin) and colophonium. SLs were detected in dandelion but not in common chickweed. Our study confirmed the importance of 1 positive reaction for emerging, not fully established, Compositae allergy. In conclusion, the overall prevalence of 4.7% in our study represents a basal SL mix detection rate of 3.4% reinforced and safely supplemented by testing with the dandelion extract.     

A retrospective study of patch tests in Chongqing, China from 2004 to 2009

Background. There has been no previous report on allergens responsible for dermatitis in southwest China. Objective. To investigate the prevalence of contact allergy in southwest China, we retrospectively analysed the patch testing results in our department from 2004 to 2009. Methods. A total of 2758 patients were patch tested with the Chinese baseline series of contact allergens (Beijing Medical University), the most common baseline series used in China. The results from patch tests were collected, analysed, and compared with clinical findings. Results. Of 2758 patients tested, 1826 (66.2%) were allergic to one or more common allergens. Five hundred (27.4%) patients had more than two contact allergies. One patient showed positive reactions to seven allergens. The most common allergens among the 1826 patients with positive reactions were nickel sulfate (39.5%), potassium dichromate (13.5%), thiomersal (11.6%), fragrance mix (6.9%), and rubber mix IV (5.8%). Nickel sensitivity was more common in female patients, and potassium dichromate sensitivity was more common in male patients (p < 0.001). Conclusion. Contact allergy in southwest China has particular characteristics, and these findings should be helpful in the development of strategies to reduce contact allergy in this geographical region.     

Contact dermatitis due to rubber boots worn by Japanese farmers, with special attention to 6-ethoxy-2,2,4-trimethyI-,1,2-dihydroquinoline (ETMDQ) sensitivity

An investigation was conducted as follows in 9 farmers with contact allergy due to rubber boots: (i) patch tests with 19 rubber additives: (ii) chemical analysis of additives in 6 pairs of rubber bouts: (iii) use tests on a hypoallergenic trial product in 5 patients. The following results were obtained: (i) in the patch tests, all 9 patients showed positive reactions to 1 or more of the nitrogen(N)-containing antioxidants (IPPD. DMRPPD. ETMDQ): (ii) ETMDQ was detected in 1 pair rubber boots, and IPPD and DMBPPD in another pair: (iii) no patient using hypoallergenic boots during rice-planting had recurrent dermatitis. N-containing antioxidants. such as IPPD. DMBPPD and ETMDQ, were thus considered as the main causative agents and the trial product was found useful for managing contact dermatitis. Contact allergy due to ETMDQ in rubber is reported here for the 1st time.     

51例面部化妆品接触性皮炎的斑贴试验和光斑贴试验结果分析

目的:检测分析面部化妆品接触性皮炎患者常见致敏原。方法:回顾性分析我院面部化妆品接触性皮炎患者的临床资料、斑贴试验和光斑贴试验资料。结果:51例患者进行了斑贴试验,总体阳性率为96%。阳性率高的过敏源依次为：硫酸镍(47.1%)、氯化钴(35.3%)、甲基异噻唑啉酮(27.5%)、纺织染料混合物(19.6%)、没食子酸辛酯(19.6%)、松香(13.7%)、对苯二胺(13.7%)、硫柳汞(13.7%)、叔丁基氢醌(13.7%)、棓酸十二烷酯(13.7%)。46例患者完成光敏实验和光斑贴检查,14例存在光敏感(30.43%);其中UVA敏感7例(15.22%),UVB敏感8例(17.39%)。光斑贴阳性率19.6%,常见致敏原依次为：依托酚那酯(6.5%)、癸基葡糖苷(6.5%)、甲酚曲唑三硅氧烷(4.3%)。结论:防腐剂、香料、重金属、乳化剂、抗氧化剂、表面活化剂等原料均可能引起面部接触致敏。面部化妆品皮炎患者还可能存在光敏反应和光变态反应。全面的斑贴试验有助于更好的帮助患者查找致敏原。     

Detection of occupational allergic contact dermatitis by patch testing

Occupational allergic contact dermatitis (OACD) is an important medical and occupational health problem. If undiagnosed, the disease may persist and even spread widely, resulting in severe and permanent disability to the worker, who may be deprived of his legal right to compensation. OACD is not uncommon in China, although many dermatologists fail to establish the connection between disease and working conditions, because they think that the diagnosis of OACD is the work of occupational medicine and that special diagnostic methods are required. The Ministry of Health and Ministry of Labour and Social Security of China have issued a new law recently to emphasize the prevention and treatment of occupational disease. It requires physicians to make an accurate diagnosis and report of occupation-related diseases. In this study, we have successfully investigated 14 cases of OACD in our hospital by patch testing the patients with a standard series of allergens and investigating by questionnaire the suspected offending occupational allergens. During a 2-year period (2001-2003), 14 patients with suspected allergic contact dermatitis were investigated and confirmed as having OACD. OACD may develop in many different occupations. In this study, nickel, 4-phenylenediamine, fragrance mix, black rubber mix, colophonium, epoxy resin and thiuram mix were identified by patch testing as the main offending allergens in such patients. These results indicate that patch testing plays a vital role in the diagnosis and identification of occupational allergens, and our study shows that OACD can often be diagnosed by patch testing patients with a standard series. The clinician should be alert to recognize the offending allergens of OACD by referring to patch testing all patients with clinically suspected contact dermatitis, and then educating the sensitized worker in how to avoid further exposure to the causative allergens.