Shoe Allergens: Retrospective Analysis of Cross-Sectional Data from the North American Contact Dermatitis Group, 2001-2004

Abstract

Background: Chemicals used in leather tanning, rubber processing, and/or adhesives are the most often-cited culprits in footwear dermatitis. Patch testing patients with suspected shoe dermatitis is essential for diagnosis and management.Objectives: The four goals for this study were to (1) determine the frequency of allergens associated with a shoe source in North American Contact Dermatitis Group (NACDG) patients with footwear allergic contact dermatitis; (2) compare these results to allergen frequencies from other published studies; (3) quantify the number of shoe-related reactions that were not identified with the NACDG standard series; and (4) identify relevant allergens not included on the NACDG standard series, based on data from other published studies. Methods: The NACDG patch-tested 10,061 patients between 2001 and 2004. Data were retrospectively analyzed by (1) allergen source coded as ''shoe,'' (2) site of dermatitis as ''feet,'' and (3) diagnosis of ''allergic contact dermatitis.''Results: Among the 109 NACDG patients with allergic contact dermatitis (ACD) of the foot and a shoe source of allergens, ptertiary butylphenol formaldehyde resin, an adhesive, was the most common allergen, accounting for 24.7% of positive patch-test results, followed by potassium dichromate (17.5%) and carba mix (11.7%). When the data were examined according to groups of allergens, rubber chemicals (40.4%) were the most frequent allergens, followed by adhesives (32.5%), and leather components (20.1%). When data from published studies were pooled, potassium dichromate (31.5%) was the most frequent allergen, followed by p-tertiary butylphenol formaldehyde resin (17.1%) and cobalt chloride (12.9%). NACDG patients were statistically more likely to have positive patch-test reactions to p-tertiary butylphenol formaldehyde resin and statistically less likely to have a positive patch-test reaction to potassium dichromate than patients represented in pooled data from past studies. Nineteen (17.4%) of the 109 NACDG patients with ACD of the foot and a shoe source of allergens were identified as having a shoe source of a relevant allergen not included in the NACDG standard series. Conclusions:In NACDG patients, the most common individual shoe allergen was p-tertiary butylphenol formaldehyde resin. As a group, rubber chemicals were most common, a finding consistent with those of other studies.

Influence of Age on Patch Tests Results

“…Also the positivity to benzocaine has increased with age. These findings are also described by other authors (5,9,22). Indeed, benzocaine is an ester local anesthetic.…”

“…Similarly, Warshaw et al (5) in a comparative study of patch tests results depending on the age conducted among 31942 patients, noted a decrease in the prevalence of atopy with age. This prevalence was 84.4% in younger patients (<18 years) and 36.4% at subjects aged more than 65 years (5).…”

“…Most of them are small substances with a molecular weight of less than 500 Daltons: called haptens (3). Positive patch test reaction can be influenced by several factors (3)(4)(5). Some studies suggest that patch test reactivity depend on age, but this role still poorly clear (6,7).…”

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

“…Similarly, Uter et al 7 found a significant trend for higher reactivity rates to thiuram mix and zinc diethyldithiocarbamate, but not mercapto mix, with increasing age. The higher rates to rubber accelerators may be a result of longer duration of exposure to sources in shoes 25 and gloves 26 or relatively greater exposure to rubber in medical devices (eg, support stockings).…”

Shoe Allergic Contact Dermatitis

“…5 From an epidemiologic standpoint, shoe ACD has been difficult to characterize because of variation in the series of allergens tested, differing shoe manufacturing processes, and changing trends in footwear across time and regions of the world. 7,8 Despite and owing to this challenge, shoe dermatitis calls for further sustained research and better understanding because it impacts so many people.…”