title: Positive patch test reactions to carba mix and iodopropynyl butylcarbamate: data from the North American Contact Dermatitis Group, 1998-2008.
abstract: BACKGROUND
  Carba mix (CM) contains 3 chemicals used as accelerators in manufacturing of rubber products and agricultural chemicals. Iodopropynyl butylcarbamate (IPBC) is a preservative used in industrial and personal care products. Potential cross-reactivity between these allergens is unclear.
  
  
  OBJECTIVE
  This study aimed to determine concomitant reaction rates between CM (3% petrolatum [pet]) and IPBC (0.1% pet and/or 0.5% pet).
  
  
  METHODS
  A retrospective cross-sectional analysis of data from the North American Contact Dermatitis Group from 1998 to 2008 was conducted. Frequencies of positive reactions, strength of reactions, and concomitant reaction rates were calculated.
  
  
  RESULTS
  A total of 25,435 patients were tested. There were 1131 allergic reactions to CM and 346 positive reactions to IPBC (either 0.1% pet and/or 0.5% pet). Fifty-two patients reacted to both allergens. Most reactions (>69%) were doubtful/weakly positive, and of those who reacted to both, most (58%) had doubtful and/or weakly positive reactions. There was a statistically significant association of concomitant reactions between CM and IPBC; formaldehyde positivity was used as control and showed statistically significant concomitant reactions.
  
  
  CONCLUSIONS
  Overall, concomitant reactions to CM and IPBC were low, and rates varied by strength of reaction. True cross-reactivity is unlikely; statistical association is likely due to frequent low-grade reactions to irritant patch test preparations.
authors.affiliation: From the *Department of Dermatology, Veterans Affairs Medical Center, University of Minnesota, Minneapolis, MN; †Division of Dermatology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada; ‡Department of Dermatology, Columbia University, New York, NY; §Dartmouth-Hitchcock Medical Center, Lebanon, NH; ∥Ohio State University Medical Center, Columbus, OH; ¶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; ††Department of Dermatology, University of Louisville, Louisville, KY; ‡‡Department of Dermatology, University of Cincinnati, Cincinnati, OH; §§Private practice, Fort Myers, FL; ∥∥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.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Warshaw
authors.forename: Srihari
authors.initials: S
authors.lastname: Raju
authors.forename: Joel G
authors.initials: JG
authors.lastname: DeKoven
authors.forename: Donald V
authors.initials: DV
authors.lastname: Belsito
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Zug
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Zirwas
authors.forename: Howard I
authors.initials: HI
authors.lastname: Maibach
authors.forename: James S
authors.initials: JS
authors.lastname: Taylor
authors.forename: Denis
authors.initials: D
authors.lastname: Sasseville
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Fowler
authors.forename: C G Toby
authors.initials: CG
authors.lastname: Mathias
authors.forename: Anthony F
authors.initials: AF
authors.lastname: Fransway
authors.forename: Vincent A
authors.initials: VA
authors.lastname: DeLeo
authors.forename: James G
authors.initials: JG
authors.lastname: Marks
authors.forename: Melanie D
authors.initials: MD
authors.lastname: Pratt
authors.forename: Frances J
authors.initials: FJ
authors.lastname: Storrs
mesh_terms: D000485:Allergens / Q000009:adverse effects*; D002219:Carbamates / Q000009:adverse effects* / Q000737:chemistry; D003429:Cross Reactions; D003430:Cross-Sectional Studies; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis / Q000209:etiology*; D004050:Ditiocarb / Q000009:adverse effects* / Q000737:chemistry; D005260:Female; D006146:Guanidines / Q000009:adverse effects* / Q000737:chemistry; D006801:Humans; D008297:Male; D010328:Patch Tests; D012189:Retrospective Studies
chemical_list: D000485:Allergens; D002219:Carbamates; D006146:Guanidines; C057051:carbamix; C106572:3-iodo-2-propynylbutylcarbamate; D004050:Ditiocarb