Allergic Contact Dermatitis Common Among Children Exposed to Cobalt

Jonathan Silverberg, MD, PhD

New findings from the George Washington University School of Medicine found that allergic contact dermatitis (ACD) reactions were common among children exposed to cobalt, with the body sites including the primary site of the trunk, face, and ears.

Cobalt is among the most common allergens to cause ACD in pediatric populations across the United States, with a global prevalence of 9.5%-17.8%.

Despite this, ACD is often underdiagnosed due to a lack of patch testing and misdiagnosis.

Previous research has indicated that children have higher rates of allergic and relevant patch test reactions to cobalt than adults, though limitations exist regarding characteristics and sources of cobalt allergy in children.

A team of investigators led by Jonathan Silverberg, MD, PhD, MPH, from the Department of Dermatology at George Washington University, examined trends in positive and relevant patch test reactions to cobalt among children with cobalt allergy in the US.

Enrollment and Testing

The team enrolled children 18 years and younger with suspected ACD, all of whom were patch tested between 2001-2018 with the North American Contact Dermatitis Group (NACDG) screening series.

Silverberg and colleagues tested cobalt in the forms of cobalt chloride 1% in petrolatum (pet.) and cobalt chloride hexahydrate 1.0% pet. These allergens were left in place for 48 hours, and reading were performed in both 48 hours and 72-168 hours following placement.

Reactions were graded on positive and negative scales which ranged from non-vesicular, indurated erythema and macular erythema or irritant, and allergen sources were classified in 228 options and 11 categories.

The Findings

Between 2001 and 2018, a total of 1919 eligible children were patch tested with cobalt. A majority (79.8%) of these patients were white, 36.2% were male, and only 6.9% were employed.

Over half (51.8%) of all participants had a history of AD, while 22.8% had asthma and 32.5% hay fever. Body sites included hands (14.9%), legs (14.7%), and face (20.3%).

Among those who were patch tested, 228 (11.9%) experienced positive allergic reactions to cobalt, and 127 (6.6%) had currently relevant reactions.

Most children had a + reaction, which indicated non-vesicular, indurated erythema (36.3%), and 37 (1.9%) had irritant reactions to cobalt.

Patients were more likely to have a primary site of trunk (P=.0160 and P=.0008, respectively, and ears (P=.0005 and P<.0001).

With these data, Silverberg and colleagues noted that their study was, to their knowledge, the first large-scale study to identify these characteristics and sources of cobalt allergy.

“Suspicion for cobalt allergy should remain high in children with suspected ACD who have dermatitis in a scattered generalized distribution, trunk or face, especially with a history of exposure to jewelry, clothing, and belts,” they wrote.

The study, "Patch testing with Cobalt in Children and Adolescents: North American Contact Dermatitis Group experience, 2001 to 2018," was published online in Contact Dermatitis.