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Differences in consumer product availability, distribution, and use may lead to national differences in contact sensitization frequencies. Objective The aim of the study was to describe the differences in contact allergy between the United States (US) and Canada. Methods This is a retrospective cross-sectional analysis of the North American Contact Dermatitis Group data from 2005 to 2016. Frequencies of demographics, clinical characteristics, positive reactions, trends, and occupations were calculated. Results A total of 28,640 patients underwent patch testing. At least 1 positive patch test was observed in 18,599 patients (US, 11,641 [66.5%]; Canada, 6958 [62.5%]). When comparing the 2 groups, US positive reactions were more likely to occur in male patients (odds ratio [OR] = 1.40, 95% confidence interval [CI] = 1.31-1.49), older than 40 years (OR = 1.30, 95% CI = 1.22-1.38), Black (OR = 2.67, 95% CI = 2.24-3.19) or Hispanic race (OR = 3.53, 95% CI = 2.61-4.78), and/or patients with scattered generalized dermatitis (OR = 1.96, 95% CI = 1.80-2.13). They were less likely to occur in patients with eczema (OR = 0.61, 95% CI = 0.57-0.65) and Asian race (OR = 0.50, 95% CI = 0.44-0.56). Nickel (US, 16.0%; Canada, 22.4%) and methylisothiazolinone (US, 13.4%; Canada, 11.0%) were the top allergens. The third most frequent was neomycin (US, 11.7%) and fragrance mix I (Canada, 10.2%). Conclusions National differences in allergen prevalence and trends exist in North America.

BACKGROUND Little is known about the epidemiology of allergic contact dermatitis in the aging US population. OBJECTIVE The aim of this study was to describe patch test results in a cohort of older adult patients evaluated in a patch testing clinic in a tertiary medical center. METHODS This study was a retrospective analysis of patch test results of adults 65 years and older from February 2013 to December 2019. RESULTS Data from a total of 169 patients 65 years and older were analyzed. Of these patients, 84.6% (143/169) had 1 or more positive reactions on patch testing, 84.6% (121/143) of which were felt to be clinically relevant and received a final diagnosis of allergic contact dermatitis. The most common allergen categories were fragrances (30.1%), preservatives (20.8%), metals (11.0%), medicaments (8.3%), and textile dyes (6.5%). The most common individual allergens were Myroxylon pereirae resin (balsam of Peru), hydroperoxide of linalool, methylisothiazolinone, nickel sulfate, and fragrance mix I. Personal products were by far the most common presumed source of allergen exposure. CONCLUSIONS Allergic contact dermatitis is a common diagnosis in the older adult population, and patch testing with allergen avoidance counseling can be an important diagnostic step and potential cure for this allergic condition.

Background Manufacturers are increasingly branding personal care products (PCPs) specifically for men. Objective The aim of the study was to characterize ingredients and claims of facial moisturizers marketed to men. Methods Men's facial moisturizers from 7 different online retailers were identified in June-September 2018. Ingredients were grouped and identified per the Ingredient Database of the Personal Care Products Council. Potential allergens were identified using the 2017 American Contact Dermatitis Society (ACDS) Core Allergen Series and 2017-2018 North American Contact Dermatitis Group Screening Series. Results Sixty-five men's facial moisturizers were identified with a total of 1930 ingredients. On average, there were 12 ACDS Core and 9 North American Contact Dermatitis Group Screening allergens per product. A total of 70.8% of products contained between 6 and 15 ACDS Core allergens. The most notable allergens were fragrances (present in 98.5% of products), propylene glycol/derivatives (32.3%), parabens (29.2%), and alkyl glucosides (26.2%). Interestingly, less than 10% of products contained the most common allergenic preservatives in PCPs: formaldehyde releasers and methylisothiazolinone. Conclusions Men's facial moisturizers commonly contain fragrances, emulsifiers, and glucosides but relatively few allergenic preservatives. This may reflect changes in modern PCP preservation. These findings are important for modern dermatologists to be aware, especially in a new era of male skincare.

Background Patch testing with the European Baseline Series (EBS) is an essential diagnostic tool for the assessment of allergic contact dermatitis. Objective The aims of the study were to describe the most common contact allergens identified with patch testing in Turkey and to establish the distribution of contact allergens among different regions in Turkey. Patients and methods Twelve centers consisting of tertiary health care institutions were included in the study. A total of 1169 patients were patch tested with the EBS from 2015 to 2017. Results A total of 596 patients (51.0%) had 1 or more positive patch test reactions to the EBS. A total of 30.2% (n = 353) of those tested had clinical relevance. Contact sensitivity was more common in young patients. The most common 10 allergens were nickel sulfate (20.4%), followed by textile dye mix (8.6%), cobalt chloride (8.3%), potassium dichromate (8.0%), p-phenylenediamine base (4.5%), balsam of Peru (4.3%), methylchloroisothiazolinone/methylisothiazolinone (3.8%), thiuram mix (3.6%), fragrance mix I (3.0%), and methylisothiazolinone (2.9%). Conclusions This study provides a comprehensive profile of patch test results with the EBS in Turkey. An ongoing decrease in contact allergy to methylchloroisothiazolinone/methylisothiazolinone and methylisothiazolinone was observed. Textile dye mix and p-phenylenediamine are beginning to pose a new risk in Turkey.

Background The usefulness of using patient's own products in patch tests for the diagnosis of allergic contact eczema is well known. However, most of the literature is based on case series published decades ago, and they are focused on cosmetics and fragrances. Objective The aim of the study was to evaluate the usefulness of using patient's own products in patch tests for the diagnosis of contact eczema in a contact dermatitis unit, describing the most frequently positive own products, as well as the most frequently responsible allergens. Methods In a 17-year period, 3514 patients were patch tested in our department. In 2429 patients, patch testing with the patients' own products was performed. Results We found that 363 patients (10.33%) reacted to their own products. In 131 cases (3.81%), reacting to their own product was the only clue for detecting the responsible allergen for allergic contact eczema. Most reactions were found for topical medications, moisturizers, and adhesives. Fragrance mix I, methylchloroisothiazolinone/methylisothiazolinone, ketoprofen, and colophony were found to be the allergens most often responsible. Conclusions It is essential to include patient's own products in the study of allergic contact eczema to make a correct diagnosis. In our series, 3.81% of the patients would not have been correctly diagnosed if their own products had not been included in patch tests.

Background Isothiazolinones are commonly used preservatives, which may cause allergic contact dermatitis. The Lovibond Isothiazolinone Test Kit (LITK) has been reported to successfully identify clinically relevant, occult isothiazolinones in patient personal care products. Objective The aim of the study was to analyze dish soaps and personal care products that do not declare isothiazolinones ("no-ISO") for the presence of isothiazolinones via 2 methods: LITK and ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Methods No-ISO dish soaps (n = 9), a convenience sample of patient products (n = 6), and controls (positive [isothiazolinone declared], n = 5; negative, n = 2) were tested with LITK (X3) and UHPLC-MS/MS. Results Several no-ISO dish soaps and personal products were positive for isothiazolinones (LITK, n = 12; UHPLC-MS/MS, n = 3). Ultrahigh-performance liquid chromatography-tandem mass spectrometry specifically identified methylisothiazolinone alone in 1 no-ISO dish soap, methylchloroisothiazolinone in another, and both in a third. Using UHPLC-MS/MS as the criterion standard, we observed the accuracy of LITK for 9 dish soaps was poor (sensitivity, 66.7%; specificity, 20%) and very poor for 6 personal care products (sensitivity, 0%; specificity, 0%). Conclusions Personal products may contain undeclared isothiazolinones. The current study found that LITK had poor accuracy for testing dish soap and personal care products. Clinicians should be aware of these factors when managing patients with contact allergy to isothiazolinones.

BACKGROUND Hair care products (HCPs) may cause both allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD). OBJECTIVES The aims of the study were to determine the prevalence of HCP-associated ICD/ACD and to characterize relevant allergens. METHODS This study is a retrospective analysis of North American Contact Dermatitis Group (NACDG) patch test data, 2001-2016. RESULTS Of 38,775 patients tested, 3481 (9.0%) had positive patch test reactions associated with HCPs. The HCP-positive patients were significantly more likely to be female (79.9% vs 66.0%) and/or have primary sites of dermatitis on the face (32.0% vs 27.8%) or scalp (15.4% vs 2.2%) compared with the HCP-negative patients (P < 0.0001). Of 4908 HCP-associated positive patch test reactions, 86.9% (n = 4263) were due to allergens on the NACDG screening series; p-phenylenediamine (35.8%), methylisothiazolinone (9.7%), methylchloroisothiazolinone/methylisothiazolinone (8.7%), and cocamidopropyl betaine (5.9%) were the most frequent. Most reactions (87.7%, 3736/4263) were currently clinically relevant. The most common job associated with 366 occupationally related NACDG HCP-associated allergens was hairdresser/cosmetologist (71.9%). Two hundred eighty-two patients (0.7%) had ICD associated with HCPs. Shampoo/conditioners were the most frequent source of NACDG HCP-associated reactions (47.3%) and HCP-associated ICD (45.0%). CONCLUSIONS Of the HCP-positive patients, 18.5% had HCP reactions to allergens not on the NACDG screening series, underscoring the importance of patch testing to expanded series in patients suspected of HCP allergy.

BACKGROUND The American Contact Dermatitis Society Contact Allergen Management Program (CAMP) database was developed to provide patients with safe alternative products free of selected contact allergens. However, the CAMP database also records valuable information including the frequency of contact allergen searches for patients. OBJECTIVES The aim of the study was to determine the relative prevalence of contact allergens in North America. METHODS Data from the CAMP database were analyzed from January 1, 2018, to January 1, 2019. The number of searches performed for each specific allergen served as a measure of the relative prevalence for each contact allergen. Results were then stratified by age, sex, atopic history, and patch screening tray used. RESULTS The 2018 CAMP data show that many of the prevalent allergens are not currently on any contact allergy screening series. These data strongly indicate that testing only to an 80-item screening series will not provide adequate care for many patients with contact allergy. The most prevalent contact allergens seen were fragrance mix, nickel, balsam of Peru, methylchloroisothiazolinone/methylisothiazolinone, and cobalt. Some important differences are seen when stratifying CAMP data by age, sex, atopic history, and patch screening tray used. LIMITATIONS Possible sources of data error exist because of lack of uniformity of patch test practices. CONCLUSIONS The CAMP database can be used to determine the relative prevalence of contact allergens, to help develop North American core screening patch test series, and to document the medical necessity of more comprehensive patch testing for patients with recalcitrant contact allergy. CAPSULE SUMMARY

Background Sensitization to methylchloroisothiazolinone (MCI) and methylisothiazolinone (MI) is a worldwide problem. Washing machine detergents are suspected to cause cutaneous symptoms in highly sensitized patients. Little is known about the persistence of isothiazolinones in clothes that have been washed. Objective The aim of the study was to analyze the possible persistence of MI, MCI, benzisothiazolinone, and octylisothiazolinone in common fabrics after machine washing. Methods Different clothes (cotton, polyester, linen, and wool) were collected, and 4 types of wash were done (control, standard, standard + conditioner, and standard + double rinse). The samples were analyzed using ultrahigh-performance liquid chromatography. Results The results showed that the concentrations of isothiazolinones were very low, independent of the type of material or wash. The highest levels were found in the control wash (hand wash), reaching a maximum of 0.4 ppm in the linen. Conclusions Our findings suggest that it is not necessary to recommend that patients sensitized to MI avoid isothiazolinones in machine detergents or fabric conditioners or to double rinse. However, after using the detergent for hand washing (the control in our study), there may remain sufficient concentrations of isothiazolinones in clothes to produce symptoms in highly sensitized patients.

BACKGROUND Methylchloroisothiazolinone/methylisothiazolinone (MCI/MI) allergy has increased for the last decade, mostly not only because of high concentrations in cosmetics but also because of its use as a biocide in industrial settings. OBJECTIVE We report an outbreak of allergic contact dermatitis in 8 workers at a water bottling plant secondary to excess levels of MCI/MI in the cooling system, found to be at levels 5 times the manufacturer's recommendations. METHODS Of 15 workers in the plastic bottle manufacturing area, 8 developed dermatitis, and 4 were referred for patch testing using a 100-allergen panel applied and interpreted in the standardized method according to the North American Contact Dermatitis Group. RESULTS Four workers had a positive reaction to MCI/MI. An investigation at the plant revealed that the concentration of MCI/MI was 365 ppm. The manufacturer's recommended level was 48 ppm. The cooling system was subsequently flushed, and biocide levels decreased to recommended levels. Afterward, all the affected workers experienced clearance of their allergic contact dermatitis. CONCLUSIONS Occupational sensitization to MCI/MI is on the rise, in this instance, because of excess levels in the cooling system. Our findings demonstrate the continued need for awareness of the allergenicity of this preservative in the occupational setting.

Background Preservatives used in cosmetics tend to be, by their nature, allergenic. Methylisothiazolinone (MI) has been used as a sole preservative in multiple cosmetics, household goods, and toiletries. A current epidemic of MI has recently been reported in Europe. Objective The aim of this study was to study the prevalence of methylchloroisothiazolinone/MI (MCI/MI) and MI allergy in a Bangkok dermatology clinic. Methods During January 2009 to June 2014, 3253 consecutive patients tested with 100 ppm (0.01%) MCI/MI and patients tested with 2000 ppm (0.2%) MI were included in the study. Results Three hundred twenty of 3253 patients (9.8%) tested for MCI/MI had a positive reaction. There was a steep increase in the prevalence of MCI/MI contact allergy from 4.8% in 2009 to 11.2% in 2011 and 17% in 2013. In the first 6 months of 2014, 22 of 54 cases tested for MI (40.7%) had a positive reaction. Among those who had a positive reaction to MI, 6 of 22 (27.3%) showed negative reaction to MCI/MI. Conclusions There is a similar prevalence of MI allergy in a Bangkok dermatology clinic as those reported in European centers such in the United Kingdom.

Background There is limited information regarding isothiazolinone content in residential wall paints in the United States. Objective The aim of this study was to evaluate the prevalence of 5 isothiazolinones-methylisothiazolinone (MI), methylchloroisothiazolinone, benzisothiazolinone (BIT), butyl BIT, and octylisothiazolinone-in US residential wall paints. Methods Forty-seven paints were obtained from retailers in Minneapolis/St Paul, Minnesota. Paint samples were assessed for the presence of the 5 isothiazolinones using high-performance liquid chromatographic-mass spectrometry. Results At least 1 isothiazolinone was detected in all 47 paints. However, no paint contained butyl BIT, and only 1 paint had octylisothiazolinone. The MI and BIT were found in 96% and 94% of the paints, respectively. Methylisothiazolinone ranged in concentration from 17 to 358 ppm, whereas BIT varied from 29 to 1111 ppm. Methylchloroisothiazolinone was found solely in oil-based paints. Isothiazolinones were declared in 15% of Safety Data Sheets but did not correlate with high-performance liquid chromatographic-mass spectrometry. One "preservative-free" paint had BIT at 71.5 ppm. Paint sheen was not statistically associated with BIT or MI concentrations. Unpigmented paints and paints with volatile organic compound claims had significantly lower concentrations of MI, but not BIT. Conclusions All paints contained at least 1 isothiazolinone. Methylisothiazolinone and BIT were the most common. Safety Data Sheets are insufficient for ascertaining isothiazolinone content in US paints.

BACKGROUND Patch testing to a standard (baseline) series of allergens is the screening tool used to identify culprit allergens in patients with contact dermatitis. The allergens and concentrations used in a standard series are constantly evolving to be most relevant to the patients being patch tested. OBJECTIVE The aim of this study was to analyze the 2011-2015 patch test results of the Mayo Clinic standard series. METHODS We retrospectively reviewed patch test reactions of standard series allergens from 2011 through 2015 and compared these results with the 2011-2012 and 2013-2014 North American Contact Dermatitis Group (NACDG) reports. CONCLUSIONS Of 2582 patients included, 1566 (60.7%) had at least 1 positive reaction, and 516 (20.0%) had at least 1 irritant reaction. The 15 allergens with the highest reaction rates (from highest to lowest) were nickel sulfate hexahydrate, methylisothiazolinone, Myroxylon pereirae resin, neomycin sulfate, cobalt (II) chloride hexahydrate, benzalkonium chloride, fragrance mix I, potassium dichromate, bacitracin, methylchloroisothiazolinone/methylisothiazolinone, carba mix, formaldehyde, p-phenylenediamine, quaternium-15, and methyldibromo glutaronitrile. Twelve (80%) of these allergens were also in the top 15 of the most recent NACDG report; the 3 allergens not in the NACDG top 15 allergens were potassium dichromate, benzalkonium chloride, and methyldibromo glutaronitrile (the latter 2 allergens are not included in their series).

Background Allergic contact dermatitis commonly occurs on the face. Facial cleansing wipes may be an underrecognized source of allergens. Objective The aim of this study was to determine the frequency of potentially allergenic ingredients in facial wet wipes. Methods Ingredient lists from name brand and generic facial wipes from 4 large retailers were analyzed. Results In the 178 facial wipes examined, a total of 485 ingredients were identified (average, 16.7 ingredients per wipe). Excluding botanicals, the top 15 potentially allergenic ingredients were glycerin (64.0%), fragrance (63.5%), phenoxyethanol (53.9%), citric acid (51.1%), disodium EDTA (44.4%), sorbic acid derivatives (39.3%), tocopherol derivatives (38.8%), polyethylene glycol derivatives (32.6%), glyceryl stearate (31.5%), sodium citrate (29.8%), glucosides (27.5%), cetearyl alcohol (25.8%), propylene glycol (25.3%), sodium benzoate (24.2%), and ceteareth-20 (23.6%)/parabens (23.6%). Of note, methylisothiazolinone (2.2%) and methylchloroisothiazolinone (1.1%) were uncommon. The top potential allergens of botanical origin included Aloe barbadensis (41.0%), chamomile extracts (27.0%), tea extracts (21.3%), Cucumis sativus (20.2%), and Hamamelis virginiana (10.7%). Conclusions Many potential allergens are present in facial wet wipes, including fragrances, preservatives, botanicals, glucosides, and propylene glycol.

Background Wet wipes are a significant allergen source for anogenital allergic contact dermatitis. Objective The aim of the study was to calculate the frequency of potentially allergenic ingredients in personal hygiene wet wipes. Methods Ingredient lists from brand name and generic personal hygiene wet wipes from 4 large retailers were compiled. Results In the 54 personal hygiene wet wipes evaluated, a total of 132 ingredients were identified (average of 11.9 ingredients per wipe). The most common ingredients were Aloe barbadensis (77.8%), citric acid (77.8%), fragrance (72.2%), sorbic acid derivatives (63.0%), tocopherol derivatives (63.0%), glycerin (59.3%), phenoxyethanol (55.6%), disodium cocoamphodiacetate (53.7%), disodium ethylenediaminetetraacetic acid (EDTA) (42.6%), propylene glycol (42.6%), iodopropynyl butylcarbamate (40.7%), chamomile extracts (38.9%), sodium benzoate (35.2%), bronopol (22.2%), sodium citrate (22.2%), lanolin derivatives (20.4%), parabens (20.4%), polyethylene glycol derivatives (18.5%), disodium phosphate (16.7%), dimethylol dimethyl hydantoin (DMDM) (14.8%), and cocamidopropyl propylene glycol (PG)-dimonium chloride phosphate (11.1%). Of note, methylisothiazolinone (5.6%) was uncommon; methylchloroisothiazolinone was not identified in the personal hygiene wet wipes examined. Conclusions There are many potential allergens in personal hygiene wet wipes, especially fragrance and preservatives.

BACKGROUND Although there are several case reports of wet wipe-associated contact dermatitis, the prevalence of wipes as a source of allergic contact dermatitis in larger populations and the responsible allergens are largely unknown. OBJECTIVE The aim of the study was to determine the prevalence of wet wipes as a source of contact allergy and the most commonly associated allergens in a North American tertiary referral patch test population. METHODS Data collected from 2011 to 2014 by the North American Contact Dermatitis Group was used to conduct a retrospective cross-sectional analysis of patient demographics and patch test results associated with the triple-digit source code for "wet wipe." RESULTS Of the 9037 patients patch tested during the study period, 79 (0.9%) had a positive patch test reaction to an allergen identified with a wet wipe source. The most commonly associated allergens were preservatives, including the following: methylisothiazolinone (MI) (59.0%), methylchloroisothiazolinone (MCI)/MI (35.6%), bronopol (2-bromo-2-nitropropane-1,3-diol) (27.4%), and iodopropynyl butylcarbamate (12.3%). Fragrance (combined) represented 12.3%. Anal/genital dermatitis was 15 times more likely (P < 0.0001) in those with wet wipe allergy. More than 92% of patients with wipe-associated contact allergy had their contact allergens detected by the North American Contact Dermatitis Group screening series. CONCLUSIONS Wet wipes are an important source of contact allergy. Preservatives are the main allergens, especially isothiazolinones.

Background Preservatives are known causes of allergic contact dermatitis. Objective The aim of this study was to determine the prevalence of preservatives in each product category in the Contact Allergen Management Program and compare prevalence with reported rates of allergic contact dermatitis. Methods Contact Allergen Management Program product information was queried based on the 53 approved preservatives for cosmetic products by the European Union and Association of Southeast Asian Nations plus 5 additional preservatives used in US products. Results Phenoxyethanol and parabens were the most common preservatives with 23.9% of products containing phenoxyethanol and 20.75% of products containing parabens. Methylisothiazolinone (MI) was found in 12.9% of products, most commonly in hair care and household products. Preservatives like MI and methylchloroisothiazolinone (MCI) that are both common in products and have a high incidence of allergic contact dermatitis are of greatest concern as contact allergy hazards. Phenoxyethanol and parabens are common and have weak sensitizing power, making them preferred preservatives. Conclusions Evaluating the prevalence of preservatives provides important information on allergen exposures. Using current positive reaction rates, the risk of sensitization to a given preservative can be more accurately estimated and may affect the use of certain preservatives by industry in the future.

Methylisothiazolinone (MIT) is widely used as biocide in hair and skin care products and in high concentrations, more than 150 mg/L, in cooling towers in the paper mill and refinery industry. This product has been recognized as a potent contact allergen and is discharged to the wastewater treatment plants (WWTP) from industrial processes or domestic usages. However, the role of MIT in biological treatment has not been characterized, and therefore, the effect of MIT on the composition and performance of activated sludge has been analyzed. For this purpose, a sequential batch reactor was fed with a synthetic solution containing 5 mg/L of MIT. Addition of MIT had shown no significant effect on organic matter metabolization (dissolved organic carbon [DOC] removal remained constant at 80-90%). On the contrary, a loss of efficiency in the nitrification process occurred (ammonium removal decreased from 90% to 20% per cycle throughout the experiment), first affecting the nitrite oxidizing bacteria and, after around 40 cycles, also the ammonium-oxidizing bacteria disappeared, as shown by fluorescence in situ hybridization analysis. Bioindicative studies based on counts of protozoa and sludge biotic index indicated that, at the end of the process, a stable and well-colonized protozoa community was obtained. Finally, respirometric tests indicated some acclimatization of the heterotrophic bacteria to MIT, as shown by shorter lag periods when the sludge was previously fed with MIT. The role of MIT in biological treatment has been characterized to increase the knowledge about this pollutant effects on activated sludge to improve WWTP performance., We would like to thank the financial support of the Spanish Ministerio de Economia y Competitividad AQUAFOTOX (CTQ2012-38754-C03-02).

Background Patch testing is an important diagnostic tool for assessment of allergic contact dermatitis (ACD). Objective This study documents the North American Contact Dermatitis Group (NACDG) patch-testing results from January 1, 2011, to December 31, 2012. Methods At 12 centers in North America, patients were tested in a standardized manner with a series of 70 allergens. Data were manually verified and entered into a central database. Descriptive frequencies were calculated, and trends analyzed using χ statistics. Results Four thousand two hundred thirty-eight patients were tested; of these, 2705 patients (63.8%) had at least 1 positive reaction, and 2029 (48.0%) were ultimately determined to have a primary diagnosis of ACD. Four hundred eight patients (9.6%) had occupationally related skin disease. There were 7532 positive allergic reactions. As compared with previous reporting periods (2009-2010 and 2000-2010), positive reaction rates statistically increased for 6 allergens: methylchloroisothiazolinone/methylisothiazolinone (5.0%; risk ratios [RRs]: 2.01 [1.60-2.52], 1.87 [1.61-2.18]), lanolin alcohol (4.6%; RRs 1.83 [1.45-2.30], 2.10 [1.79-2.47]), cinnamic aldehyde (3.9%; 1.69 [1.32-2.15], 1.53 [1.28-1.82]), glutaral (1.5%; 1.67 [1.13-2.48], 1.31 [1.00-1.71]), paraben mix (1.4%; 1.77 [1.16-2.69], 1.44 [1.09-1.92]), and fragrance mix I (12.1%; RRs 1.42 [1.25-1.61], 1.24 [1.14-1.36]). Compared with the previous decade, positivity rates for all formaldehyde-releasing preservatives significantly decreased (formaldehyde 6.6%; RR, 0.82 [0.73, 0.93]; quaternium-15 6.4% RR 0.75 [0.66, 0.85]; diazolidinyl urea 2.1%; RR, 0.67 [0.54, 0.84]; imidazolidinyl urea 1.6%, 0.60 [0.47, 0.77]; bronopol 1.6%; RR, 0.60 [0.46, 0.77]; DMDM hydantoin 1.6%; RR, 0.59 [0.54, 0.84]). Approximately a quarter of patients had at least 1 relevant allergic reaction to a non-NACDG allergen. In addition, approximately one-fourth to one-third of reactions detected by NACDG allergens would have been hypothetically missed by T.R.U.E. TEST (SmartPractice Denmark, Hillerod, Denmark). Conclusions These data document the beginning of the epidemic of sensitivity to methylisothiazolinones in North America, which has been well documented in Europe. Patch testing with allergens beyond a standard screening tray is necessary for complete evaluation of occupational and nonoccupational ACD.

Background Preservatives are indispensable agents used to prevent bacterial and fungal contamination of cosmetics, personal care products, domestic preparations, and industrial products. Objective We evaluated patch-test data at the National Skin Centre, Singapore, from 2006 to 2011 to identify the trends in preservative contact allergies. Methods All patients with suspected contact dermatitis were patch tested to 4 preservatives within the modified European standard series. Patients were also tested with 7 preservatives from our special series if clinically indicated. Results Three thousand one hundred seventy-seven patients were tested to preservatives in the standard series. Sensitization frequencies were all greater than 1%: parabens (2.58%), methylchloroisothiazolinone/methylisothiazolinone (1.75%), quaternium 15 (1.43%), and methyldibromoglutaronitrile (1.2%). There was no change in trends in sensitization frequencies from 2006 to 2011, with no increase in sensitization frequency to methylchloroisothiazolinone/methylisothiazolinone. The sensitization frequencies for methyldibromoglutaronitrile/phenoxyethanol and diazolidinylurea were 2.03% and 1.37%, respectively, and remained less than 1% for bronopol, imidazolidinyl urea, and 2-phenoxyethanol. A rate of 0% was seen for 1,3-dimethylol-5,5-dimethyl hydantoin and formaldehyde; 9.4% of positive patch-test results became positive only at day 7. Conclusions Preservatives are common causes of allergic contact dermatitis. This should be considered when introducing new preservatives into the market. Day 7 readings are important to detect late reactions.

Background The isothiazolinones methylchloroisothiazolinone and methylisothiazolinone (MCI/MI) are the active ingredients in a frequently used preservative in cosmetic, household, and industrial products. Objectives This study reviewed our department's cases of allergic contact dermatitis caused by MCI/MI, outlining their clinical presentation and possible sources of sensitization. The effect of changing the concentration of MCI/MI from 0.01% to 0.02% in the British Society for Cutaneous Allergy baseline series was also measured. Methods A total of 964 patients were patch tested to the British Society for Cutaneous Allergy baseline series in our department over 4 years. Patients were tested either to 0.01% MCI/MI (697) or 0.02% MCI/MI (267). Results Twenty-one patients (2.2%) had positive reactions to MCI/MI. Of patients tested to 0.02% MCI/MI, 3.8% had a positive reaction compared with 1.6% of those tested to MCI/MI 0.01%. Ten patients (48%) had perianal dermatitis; of these, 50% had used moist toilet wipes. Conclusions We highlight MCI/MI as important contact allergens found in moist toilet wipes and should be considered particularly in patients with facial, hand, and perianal allergic contact dermatitis. Patch testing to 0.01% MCI/MI may underestimate its allergenic potential, missing more than half of allergic cases compared with testing to 0.02%. To identify isothiazolinone allergy, we recommend that 0.02% MCI/MI should be used in baseline series.

Background: Whereas allergy to vehicle ingredients (ie, excipients and preservatives) in topical steroid vehicles is well recognized, there are no data regarding which vehicle ingredients are in common use or on which vehicles and active molecules are associated with which ingredients. Objective: To produce descriptive data on the use of allergenic vehicle ingredients in prescription topical corticosteroids. Methods: The package insert for every steroid in widespread use in the United States was obtained from the manufacturer and used to generate an ingredient list for the product. Results: There are seven vehicle ingredients that are commonly used in topical corticosteroid vehicles that are well-known allergens: propylene glycol, sorbitan sesquioleate, formaldehyde-releasing preservatives, parabens, methylchloroisothiazolinone/ methylisothiazolinone, lanolin, and fragrance. Of 166 topical corticosteroids, 128 (including all creams) had at least one of these vehicle ingredients. More generic products were free of allergens than were branded products. Solutions and ointments were the least allergenic vehicles. The most commonly present potential allergens were propylene glycol and sorbitan sesquioleate. Conclusions: Most prescription topical corticosteroids have the potential to cause allergic contact dermatitis owing to vehicle ingredients. Dermatologists should be aware of this possibility and should consider prescribing agents that do not contain potentially allergenic vehicle ingredients.

This is the second United States multicenter study of human skin sensitization to methylchloroisothiazolinone/methylisothiazolinone (MCI/MI). From January 1991 through March 1992 patients treated in 11 patch test clinics were patch tested to 100 ppm MCI/MI, formaldehyde 1% aqueous, quaternium-15 2% petrolatum, imidazolidinyl urea 2% petrolatum, and paraben mix 12% petrolatum. Twenty-three of the 1,259 patch test patients (1.8%) had positive patch test reactions to MCI/MI. Thirteen of the 23 (56.5%) were thought to be relevant to the presenting dermatitis. The frequency of positive patch test reactions to the other allergens was quaternium-15, 7.2%; formaldehyde, 7.1%; imidazolidinyl urea, 2.2%; and paraben mix, 1.4%. Skin sensitization to MCI/MI has not changed significantly since the first United States multicenter study in 1988 to 1989. The rate of positive patch test responses to MCI/MI was comparable with that for parabens and imidazolidinyl urea and significantly less than for formaldehyde and quaternium-15.