Erin M Warshaw1, Srihari I Raju, C G Toby Mathias, Joel G DeKoven, Donald V Belsito, Howard I Maibach, James S Taylor, Denis Sasseville, Kathryn A Zug, Matthew J Zirwas, Joseph F Fowler, Vincent A DeLeo, James G Marks, Melanie D Pratt, Frances J Storrs. 1. From the *Department of Dermatology, Veterans Affairs Medical Center, University of Minnesota, Minneapolis, MN; †Department of Dermatology, University of Cincinnati, Cincinnati, OH; ‡Division of Dermatology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; §Department of Dermatology, Columbia University, New York, NY; ∥Department of Dermatology, University of California San Francisco, San Francisco, CA; ¶Department of Dermatology, Cleveland Clinic, Cleveland, OH; #Division of Dermatology, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada; **Dartmouth-Hitchcock Medical Center, Lebanon, NH; ††Ohio State University Medical Center, Columbus, OH; ‡‡Department of Dermatology, University of Louisville, Louisville, KY; §§Department of Dermatology, Pennsylvania State University, Philadelphia, PA; ∥∥Division of Dermatology, University of Ottawa, Ottawa, Ontario, Canada; and ¶¶Department of Dermatology, Oregon Health Science University, Portland, OR.
Abstract
BACKGROUND: Mercaptobenzothiazole (MBT) and mercapto compounds are primarily used in rubber products. OBJECTIVE: This study aimed to examine concomitant-positive rates of MBT (1% pet) and the 4-part mercapto mix (MM) (1% pet). DESIGN: This is a retrospective cross-sectional data from the North American Contact Dermatitis Group. RESULTS: A total of 30,880 patients were patch tested to MM and MBT. There were 333 positive reactions to MM and 427 positive reactions to MBT. Ninety-eight patients were positive to MM alone, 192 to MBT alone, and 235 reacted to both. Forty-five percent (192/427) of MBT reactions would have been missed by only testing to MM, and 29% (98/333) of MM reactions would have been missed by testing to MBT alone. Most of these "missed" reactions, however, were doubtful (+/-) or mild (+) (MBT, 65%; MM, 78%), whereas most reactions in patients who reacted to both were moderate (++) and/or strong (+++) (52.3%). Gloves were the most common source. CONCLUSIONS: Mercaptobenzothiazole is the preferential screening allergen for mercapto compounds because of the following: (1) greater proportion of missed reactions with MM; (2) greater proportion of doubtful/mild reactions in the missed group for MM; and (3) in the group positive to both, the low rate (2%) of moderate/strong reactions to MM and doubtful/mild reactions to MBT as compared with the converse (21%). Mercapto mix may be useful in an auxiliary rubber series.
BACKGROUND:Mercaptobenzothiazole (MBT) and mercapto compounds are primarily used in rubber products. OBJECTIVE: This study aimed to examine concomitant-positive rates of MBT (1% pet) and the 4-part mercapto mix (MM) (1% pet). DESIGN: This is a retrospective cross-sectional data from the North American Contact Dermatitis Group. RESULTS: A total of 30,880 patients were patch tested to MM and MBT. There were 333 positive reactions to MM and 427 positive reactions to MBT. Ninety-eight patients were positive to MM alone, 192 to MBT alone, and 235 reacted to both. Forty-five percent (192/427) of MBT reactions would have been missed by only testing to MM, and 29% (98/333) of MM reactions would have been missed by testing to MBT alone. Most of these "missed" reactions, however, were doubtful (+/-) or mild (+) (MBT, 65%; MM, 78%), whereas most reactions in patients who reacted to both were moderate (++) and/or strong (+++) (52.3%). Gloves were the most common source. CONCLUSIONS:Mercaptobenzothiazole is the preferential screening allergen for mercapto compounds because of the following: (1) greater proportion of missed reactions with MM; (2) greater proportion of doubtful/mild reactions in the missed group for MM; and (3) in the group positive to both, the low rate (2%) of moderate/strong reactions to MM and doubtful/mild reactions to MBT as compared with the converse (21%). Mercapto mix may be useful in an auxiliary rubber series.