A research team led by Kathryn Zug '84, a dermatologist at Dartmouth-Hitchcock Medical Center, discovered that children and adults are equally likely to have allergic contact dermatitis, but react to different allergens. The study will be a useful guide for dermatologists testing for allergies in eczema patients, Zug, also a Dartmouth Medical School professor, said.
Zug analyzed data collected between 2001 and 2004 from patch tests administered to children and adults across the nation by 13 members of the North American Contact Dermatitis Group. She and her colleagues found significant differences between the frequencies of positive reactions to allergens in children and adults.
The patch test results of 391 children and 9,670 adults showed that, although children and adults tested positive for allergens at approximately the same rate, children were most likely to have positive reactions to the metal nickel whereas adults were most likely to have positive reactions to the chemical neomycin, an ingredient in skin creams. Patch tests are prepared with chemicals in appropriate concentrations and applied to the backs of patients, where they are left for two days. A positive reaction is said to have occurred if the part of the back to which that chemical was applied appears irritated when the patch is removed.
Twenty-eight percent of the children in the study tested positive for nickel allergies, a statistic Zug believes could affect the amount of nickel used in items such as jewelry and belt buckles.
"There is some interest in regulating nickel concentration, and this study lends some epidemiology as to why that would be a good idea," she said.
The results of this study can also be helpful to dermatologists looking to isolate allergens affecting their patients.
"This is a very nice guide for dermatologists that do this kind of testing as to which are the most important items to look for," Zug said.
The study's findings concerning allergic contact dermatitis among children may also lead to more effective diagnoses, she said.
"I think that often eczema is used to indicate one type of condition, but there are different types of eczema," Zug said. "This study points out that children can develop allergic contact dermatitis as much as adults, so doctors ought to test whether children have this condition."
Differences in chemicals that adversely affect children and adults can be attributed to differences in the patient's age when exposed to specific chemicals, Zug said.
"You must acquire the allergy by exposure -- you are not born with it," she said.
Because many of the chemicals tested are ingredients in common toiletries, the results of this study could impact how companies manufacture their products, according to Zug.
"If a company wanted to formulate a product for children that would cause fewer allergies, they could look to this data," she added.
According to Zug the term "hypoallergenic" has neither a real definition or a Food and Drug Administration-approved definition. Therefore when companies claim their product is hypoallergenic, there is no guarantee that allergic reactions will be avoided, she said.
Zug is continuing research on the frequency of various allergens, and is also looking into the genetics of allergies. Zug's research is the first multicenter study to evaluate the frequency of reaction to allergens in North American children with patch testing, according to a DMS news release.
