Chemical Identification and Confirmation of Contact Allergens

Abstract

Identification of the etiological chemical agent(s) associated with a case(s) of allergic contact dermatitis (ACD) is important for both patient management and public health surveillance. Traditional patch testing can identify chemical allergens to which the patient is allergic. Confirmation of allergen presence in the causative ACD-associated material is presently dependent on labeling information, which may not list the allergenic chemical on the product label or safety data sheet. Dermatologists have expressed concern over the lack of laboratory support for chemical allergen identification and possibly quantification from patients' ACD-associated products. The aim of the study was to provide the clinician a primer to better understand the analytical chemistry of contact allergen confirmation and unknown identification, including types of analyses, required instrumentation, identification levels of confidence decision tree, limitations, and costs. New chemicals are continuously introduced into the market. Several animal-based screening methods (ie, guinea pig maximization test and the marine local lymph node assay) have been used to identify chemicals with contact allergenic potential; however, patients are continually diagnosed with allergic contact dermatitis (ACD) to previously unrecognized chemical allergens. Between 2008 and 2015, 172 new contact allergens were identified through patient patch testing (119 of these were associated with ACD) and reported in Contact Dermatitis and Dermatitis. 1 The actual number of new contact allergens is likely much higher because of incomplete product labeling, new allergens identified by patch testing but not reported in the literature, and those associated with ACD for which the Address reprint requests to

Contact Allergy: Occurrence and Susceptibility

“…23 Several studies have shown that NAT1 activity is detectable in the cytosol in different tissues in humans and animals. 9,16,24,25 In this study, we reconfirmed that NAT1 can indeed be considered as a cytosolic enzyme, as we showed NAT1 to be expressed in human skin cytosol.…”

“…The ROAT is performed without occlusion; therefore, the potential development of irritant and false-positive reactions is minimized. 24,25 If dermatitis occurs at the ROAT test site, a contact allergy to the product is strongly suspected. Notably, a product may contain skin irritants that create an inflammatory environment, in which case the threshold for an elicitation reaction is lowered.…”

“…These include sex, age, and occupational dermatitis. [22][23][24][25][26][27][28][29][30] Women tend to have a higher prevalence of contact allergies than men. 26 Furthermore, several studies have evaluated the effect of age on the elicitation of contact allergy.…”

“…Several studies have been published on the effect of sex on the development of contact allergy. [21][22][23][24] It was assumed that increased female sensitivity to contact allergens is most likely due to a higher exposure to contact allergens than males. 21,23 The current study shows that females are indeed more exposed to scented products and consequently may be more frequently sensitized to fragrance allergens than males.…”

“…Chemical analysis is an effective method in the search for the culprit allergen in insufficiently labelled products. 24 Notwithstanding the significant value of chemical analysis, some important limitations must be considered. It is necessary to have specific knowledge of chemistry as well as access to the appropriate equipment.…”