Cutaneous delayed-type hypersensitivity in patients with atopic dermatitis: reactivity to topical preservatives.

BACKGROUND: Patients with atopic dermatitis (AD) have chronic dry skin to which they frequently apply skin care products containing preservatives, and they are predisposed to developing cutaneous delayed-type hypersensitivity. OBJECTIVE: We sought to compare the rates of positive patch test reactions to allergens on the North American Contact Dermatitis Group (NACDG) standard tray among patients with and without AD and to assess whether atopic patients in our database were more likely to patch test positive to preservatives. METHODS: A total of 2453 patients underwent patch testing to the NACDG standard screening series. The incidence of positive patch test reaction among patients with AD (n = 342) and without AD (n = 2111) was assessed. Statistical analysis was done using a χ(2) test. RESULTS: Compared with nonatopic patients, patients with AD were statistically more likely to have positive patch tests. AD was associated with contact hypersensitivity to quaternium-15, imidazolidinyl urea, DMDM hydantoin, and 2-bromo-2-nitropropane-1,3-diol but not to parabens, formaldehyde, or diazolidinyl urea. LIMITATIONS: Only patients suspected of having allergic contact dermatitis were tested. Our population was geographically limited to metropolitan Kansas City, MO, and metropolitan New York City, NY. CONCLUSIONS: Patients with AD should avoid the use of skin care products preserved with formaldehyde releasers.

Positive patch test reactions in older individuals: retrospective analysis from the North American Contact Dermatitis Group, 1994-2008.

BACKGROUND: Relatively little is known about the epidemiology of allergic contact dermatitis in older individuals. OBJECTIVES: We sought to determine the frequency of positive and clinically relevant patch test reactions in older individuals (≥ 65 years old) referred for patch testing, and to compare these results with those of adults (≤ 64-19 years) and children (<18 years). DESIGN: This was a retrospective cross-sectional analysis of North American Contact Dermatitis Group data from 1994 to 2008. RESULTS: A total of 31,942 patients (older n = 5306; adults n = 25,028; children n = 1608) were patch tested. The overall frequency of at least one allergic reaction in older individuals was 67.3% as compared with 66.9% for adults (P = .5938) and 47% for children (P = .0011). Reaction rates that were statistically higher in older individuals as compared with both adults and children included: Myroxylon pereirae, fragrance mix I, quaternium-15, formaldehyde, imidazolidinyl urea, diazolidinyl urea, neomycin, bacitracin, methyldibromo glutaronitrile, methyldibromo glutaronitrile/phenoxyethanol, ethyleneurea melamine formaldehyde mix, and carba mix (P values < .0004). Patch test reaction rates that were significantly lower in older individuals than both comparison groups included: nickel, thimerosal, and cobalt (P values < .0001). LIMITATIONS: Referral population was a limitation. CONCLUSIONS: Older individuals were more likely to have at least one positive patch test reaction as compared with children, but had similar rates to adults. The frequency of positive reactions to specific allergens differed by age group, most likely as a result of exposures.

Frequency of sensitization to common allergens: comparison between Europe and the USA.

BACKGROUND: Previously, contact allergy to formaldehyde and quaternium-15 was found to be more prevalent in the United States than in Europe. No such data have been assessed for other contact allergens. OBJECTIVE: Determine any differences in frequencies of sensitization to contact allergens in the United States and Europe. METHODS: Literature study. Comparison of reported frequencies of sensitization to contact allergens routinely tested both in the United States and Europe in recent, large, multicentre studies. Because of the heterogeneity of studies and background parameters, statistical evaluation was not attempted. RESULTS: Major differences were found only for neomycin (USA 10.0-11.8%, mean 11.4%; Europe 1.2-5.4%, mean 2.6%). Most allergens had somewhat higher prevalence in the United States, with rates versus Europe ranging from 1.3 to 1.9. CONCLUSIONS: Contact allergy to neomycin is much more prevalent in the United States. Stricter selection of patients for patch testing in United States tertiary referral centres may result in 50% more positive reactions compared to European studies.

Sensitization to Formaldehyde in Northeastern Italy, 1996 to 2012.

BACKGROUND: Formaldehyde is a widely used organic compound, used in several applications (hard thermoset resins, adhesives, disinfectants, tissue fixatives, etc), in its free form or released by formaldehyde releaser products. Its use is under control due to its toxic, carcinogenic, and allergenic properties. OBJECTIVE: The aim of this study was to investigate the frequency of formaldehyde sensitization, time trend, and correlation to occupations. METHODS: This study is a cross-sectional study on a population of 23,774 patients tested from 1996 to 2012 in Northeastern Italy. RESULTS: Frequency of sensitization was 3.3%, without any significant time trend. Hands (39.8% overall) and face (25.6% females, 15.5% males) were mainly involved. We found a trend toward decrease by age in females (3.11% in first quintile [14-26 years], 2.29% in fifth quintile [59-97 years], P < 0.01). On a logistic regression analysis (control group: white-collar workers), we found associations in health care (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.04-1.81), wood (OR, 2.14; 95% CI, 1.30-3.51), and textile (OR, 1.79; 95% CI, 1.14-2.79) sectors and professional drivers (OR, 1.94; 95% CI, 1.05-3.60). We found a high rate of cosensitization to formaldehyde in patients with positive patch test reactions to quaternium-15 (OR, 18.7; 95% CI, 12.6-27.7). CONCLUSIONS: Sensitization to formaldehyde is relevant in our population, especially in the health care sector, wood and textile industries, and professional drivers. No significant time trend was found.

Allergic contact dermatitis due to hexamethylenetetramine in core molding.

Hexamethylenetetramine is an odorless powder and slowly liberates formaldehyde in an acid medium or when heated. It is usually used in the manufacture of formaldehyde resins, rubber and the explosive, cyclonite. It is also used as a hardener in core molding processes. It was reported as one of the formaldehyde releasers and as a cause of formaldehyde contact dermatitis. We report an allergic contact dermatitis due to hexamethylenetetramine, with a positive patch test reaction to hexamethylenetetramine (1% pet.) but not to formaldehyde (2% aq.). We concluded that this case was an allergic contact dermatitis from hexamethylenetetramine itself.

Diazolidinyl urea: incidence of sensitivity, patterns of cross-reactivity and clinical relevance.

Diazolidinyl urea (DIAZ) is a formaldehyde-releasing preservative used in cosmetics and personal-care products, which has been identified as a sensitizing agent in contact dermatitis. To determine whether DIAZ sensitization is secondary to formaldehyde release or due to its own allergenic properties, we reviewed 708 consecutive patch tests of patients with various dermatologic complaints. Profiles of the 58 individuals (8%) with DIAZ sensitivity were analyzed with respect to sex, age, exposures, and chronicity of dermatitis. Significant coexistent biocide reactivity was demonstrated for DIAZ and formaldehyde (81%); 12% reacted to DIAZ alone. We conclude that the primary mode of sensitization of DIAZ is via formaldehyde release and that independent contact allergy is less frequent.