Shoe Allergens
Shoe Allergens
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, p-tertiary 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.
THE PREVALENCE OF SHOE DERMATITIS among patients with contact dermatitis has been estimated at 3.3 to 11.7%. In children, the feet are one of the most common sites for contact dermatitis, and footwear is the second leading cause of contact dermatitis cited. Disparities in the series of allergens tested, different methods of shoe manufacture, environmental factors, and varying social trends in footwear across the globe contribute to the difficulty of accurately characterizing the epidemiology of allergic contact dermatitis (ACD) from shoes.
The main components of shoe construction include uppers/straps, soles, insoles, and heel and toe counters (stiff elements that maintain shoe shape). Adhesives are used to attach these parts together. (For a full review of shoe manufacturing, readers are referred to the excellent chapter "Shoes" in Contact Dermatitis). Chemicals associated with leather, rubber, and adhesives have long been recognized as potentially sensitizing agents. The most common allergens associated with ACD of the feet vary among studies but are typically those involved in leather or rubber processing. The warm moist environment and occlusion provided by shoes are thought to potentiate the development of ACD.
ACD from shoes can be debilitating, and the causative agent may not be obvious. Patch testing patients with suspected shoe ACD is essential for identifying the responsible allergen and for guiding shoe selection. Freeman observed that after a mean of 2.9 years from patch testing, 87.5% of 55 patients with footwear dermatitis had improvement or resolution of their symptoms.
Studies evaluating the frequency of allergens associated with dermatitis of the feet have been conducted in Europe, the Middle East, Asia, Australia, and regionally in North, and South America. To our knowledge, the frequency of allergens associated specifically with a shoe source has not been investigated broadly in North America. The North American Contact Dermatitis Group (NACDG) has collected aggregated data from patients patch-tested across North America from 1971 to the present. Beginning in 2001, a specific three-digit allergen source was coded for each NACDG standard allergen as well as for other relevant allergens not included on the NACDG standard series. The four goals for this retrospective study were (1) to determine the frequency of allergens associated with a shoe source in NACDG patients with footwear ACD, (2) to compare these results to allergen frequencies from other published studies, (3) to quantify the number of shoe-related reactions that were not identified with the NACDG standard series, and (4) to identify relevant allergens not included on the NACDG standard series, based on data from other published studies.
Abstract and Introduction
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, p-tertiary 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.
Introduction
THE PREVALENCE OF SHOE DERMATITIS among patients with contact dermatitis has been estimated at 3.3 to 11.7%. In children, the feet are one of the most common sites for contact dermatitis, and footwear is the second leading cause of contact dermatitis cited. Disparities in the series of allergens tested, different methods of shoe manufacture, environmental factors, and varying social trends in footwear across the globe contribute to the difficulty of accurately characterizing the epidemiology of allergic contact dermatitis (ACD) from shoes.
The main components of shoe construction include uppers/straps, soles, insoles, and heel and toe counters (stiff elements that maintain shoe shape). Adhesives are used to attach these parts together. (For a full review of shoe manufacturing, readers are referred to the excellent chapter "Shoes" in Contact Dermatitis). Chemicals associated with leather, rubber, and adhesives have long been recognized as potentially sensitizing agents. The most common allergens associated with ACD of the feet vary among studies but are typically those involved in leather or rubber processing. The warm moist environment and occlusion provided by shoes are thought to potentiate the development of ACD.
ACD from shoes can be debilitating, and the causative agent may not be obvious. Patch testing patients with suspected shoe ACD is essential for identifying the responsible allergen and for guiding shoe selection. Freeman observed that after a mean of 2.9 years from patch testing, 87.5% of 55 patients with footwear dermatitis had improvement or resolution of their symptoms.
Studies evaluating the frequency of allergens associated with dermatitis of the feet have been conducted in Europe, the Middle East, Asia, Australia, and regionally in North, and South America. To our knowledge, the frequency of allergens associated specifically with a shoe source has not been investigated broadly in North America. The North American Contact Dermatitis Group (NACDG) has collected aggregated data from patients patch-tested across North America from 1971 to the present. Beginning in 2001, a specific three-digit allergen source was coded for each NACDG standard allergen as well as for other relevant allergens not included on the NACDG standard series. The four goals for this retrospective study were (1) to determine the frequency of allergens associated with a shoe source in NACDG patients with footwear ACD, (2) to compare these results to allergen frequencies from other published studies, (3) to quantify the number of shoe-related reactions that were not identified with the NACDG standard series, and (4) to identify relevant allergens not included on the NACDG standard series, based on data from other published studies.
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