Allergic contact dermatitis to detergents: A multicenter study to assess prevalence

Background: Allergic contact dermatitis (ACD) to optical brighteners and enzymes in laundry detergents was the focus of numerous reports in the early 1970s. Subsequently, there has been little published on the incidence of allergic reactions to chemicals in laundry detergents. Nonetheless, consumers and physicians continue to ascribe allergic contact reactions to laundry detergents. Objective: This article reports the findings of a multicenter study on the prevalence of patch test reactions to a liquid and a granular laundry detergent provided by Procter & Gamble Company (Cincinnati, Ohio). Methods: Patients referred to members of the North American Contact Dermatitis Group for evaluation of potential ACD were invited to participate in the study, which involved the placement of 2 patch tests (a 0.1% aqueous dilution of a granular laundry detergent and a 0.1% aqueous dilution of a liquid laundry detergent). Whether the patients had atopic dermatitis and whether they or their physicians felt that their dermatitis might be related to laundry detergents were noted. Reactions to the laundry detergents were correlated with allergic reactions to the following screening chemicals: fragrances, nickel, and potassium dichromate. Patients who experienced a reaction to at least one of the laundry detergents could enter phase II of the study, which involved testing to varying dilutions of the laundry detergents, to 0.1% sodium lauryl sulfate (as an irritant control), and to laundered patches of cotton. Patients positive in phase II could enter phase III, which involved wearing a garment laundered with the detergent. Phases II and III were double blinded. Results: Of the 3120 patients seen by members of the North American Contact Dermatitis Group during the 2 years of this study, 738 patients volunteered to enroll. Enrollment was not statistically randomized. Of these 738, 5 (0.7%) had positive patch test reactions to granular laundry detergent (0.1%, aqueous); 3 of these 5 also had positive reactions to the liquid laundry detergent (0.1%, aqueous). In 4 of the 5 patients, the reaction to detergent was thought to have present relevance to their dermatitis; in 1 of the 5, the reaction was deemed to have past relevance. One of these 5 patients had allergy to fragrances. None of the patients was positive to nickel or chromate. Two of the 5 entered phases II and III. Of these 2 patients, 1 had essentially negative repeat dilutional patch testing and "use testing" suggesting that the earlier reaction patterns may have been irritant. The remaining patient had positive dilutional reactions to both the liquid and granular laundry detergent; however, she also had a positive reaction to sodium lauryl sulfate and to a swatch from a T-shirt laundered without detergent. Upon "use testing" in phase III, this latter patient experienced diffuse dermatitis under both the half of the T-shirt laundered with detergent and that laundered without detergent. Conclusion: Laundry detergents appear to be a rare cause of ACD. Among 738 patients with dermatitis, 5 (0.7%) reacted to a 0.1% aqueous dilution of a laundry detergent. Only 2 of these 5 patients could be evaluated in greater detail to differentiate allergic from irritant patch test reactions to detergents. Upon further testing in 2 patients, the reaction in 1 of 2 could not be reduplicated and the reaction in the other was invoked both by the detergents and the controls. Thus, whether our study patients were truly allergic and, if so, what the allergenic material(s) in detergents might be, remains unknown. Therefore the reported incidence rate for detergent-induced allergy of 0.7% in dermatitic patients may be too high, possibly because of false-positive irritant reactions.