Positive patch-test reactions to iodopropynyl butylcarbamate: retrospective analysis of North American contact dermatitis group data, from 1998 to 2008.

BACKGROUND: iodopropynyl butylcarbamate (IPBC), a commonly used preservative, is found in industrial and personal care products. OBJECTIVE: to evaluate prevalence, clinical relevance, occupational relationship, and sources of positive reactions to IPBC in patients in North America. METHODS: the North American Contact Dermatitis Group (NACDG) tested IPBC 0.1% and/or 0.5% in petrolatum (pet) between 1998 and 2008. Two patient groups of interest were defined, based on patch-test reactions to IPBC: weak (+) reactors and strong (++ or +++) reactors. Patient characteristics, site(s) of dermatitis, sources of positive reactions, clinical relevance, and occupational relevance to IPBC were tabulated. RESULTS: of the 25,321 patients tested, there were 226 (0.9%) weak reactors and 67 (0.3%) strong reactors. For IPBC-positive patients, the most frequent sites of dermatitis were scattered generalized distribution, hands, and arms. The majority (> 50%) of currently relevant reactions were to personal care products, and most reactions (> 90%) were not related to occupation. Only four of the strong reactors had definite clinical relevance (positive use-test reaction or positive patch-test reaction to a product containing IPBC). The frequency of positive reactions increased (0.2% vs 1.5%) when the higher concentration of IPBC was utilized, but most (> 64%) were weak reactions, of which some were likely irritant. CONCLUSIONS: allergy to IPBC is relatively uncommon. When clinically relevant, personal care products were the most likely allergen source. Because IPBC is a marginal irritant, caution should be utilized when testing with higher concentrations of IPBC (≥ 0.5% pet) and when interpreting weak (+) reactions. Verification of clinical relevance by use test or repeat patch testing or both is also important.

North American Contact Dermatitis Group patch-test results, 2003-2004 study period.

BACKGROUND: Allergic contact dermatitis is a significant cause of both occupational and non-occupational skin disease. Patch testing is an important diagnostic tool for the determination of responsible allergens. OBJECTIVE: This study reports the results of patch testing by the North American Contact Dermatitis Group from January 1, 2003, to December 31, 2004. METHODS: At 13 centers in North America, patients were tested with the same screening series of 65 allergens, with a standardized patch-testing technique. Data were recorded on standardized forms and manually verified and entered. Descriptive frequencies were calculated, and trends were analyzed with chi-square statistics. RESULTS: A total of 5,148 patients were tested. Of these, 3,432 (66.7%) had at least one positive reaction, 2,284 (44.4%) were ultimately determined to have primary allergic contact dermatitis, and 676 (13.1%) had occupation-related skin disease. There were 9,762 positive allergic reactions. Compared to the previous reporting period (2001-2002), allergies to nickel, budesonide, mercaptobenzothiazole, and paraben mix were at least 1.12 times more common (all p values < .03). Compared with the previous 8 years (1994-2002), only the prevalence rates of allergies to nickel and budesonide were statistically significantly higher (p values < .003). CONCLUSION: Allergic contact dermatitis from nickel and budesonide may be increasing in North America. These results again underscore the value of patch-testing with many allergens.

Contact dermatitis of the hands: cross-sectional analyses of North American Contact Dermatitis Group Data, 1994-2004.

BACKGROUND: Hand dermatitis, including irritant and allergic contact dermatitis (ACD), is common. OBJECTIVE: To evaluate allergens, relevant irritants, sources and occupations associated with hand contact dermatitis using North American Contact Dermatitis Group (NACDG) data. METHODS: A cross-sectional analysis of 22,025 patients patch tested between 1994 and 2004. RESULTS: Hand involvement was found in 6953 patients; 959 had ACD as the only diagnosis. In these 959 patients, the 12 most frequent relevant allergens were quaternium-15 (16.5%), formaldehyde (13.0%), nickel sulfate (12.2%), fragrance mix (11.3%), thiuram mix (10.2%), balsam of Peru (9.6%), carba mix (7.8%), neomycin sulfate (7.7%), bacitracin (7.4%), methyldibromoglutaronitrile/phenoxyethanol 2.0% (7.4%), cobalt chloride (6.5%), and methyldibromoglutaronitrile/phenoxyethanol 2.5% (6.3%). Rubber allergens were most commonly associated with occupation. One third of patients with hand ACD had identifiable relevant irritants. LIMITATIONS: Cross-sectional analyses prevent evaluation of causal associations. CONCLUSION: In NACDG patients with hand ACD, the most common allergens included preservatives, metals, fragrances, topical antibiotics, and rubber additives.