Biocide patch tests

Routine patch testing with a series of 6 industrial biocides containing methylene-bis-thiocyanate (Cytox 3522), benzisothiazolin-3-one (BIT), chlorocresol (Preventol CMK), 2-n-octyl-4-isothiazolin-3-one (Kathon 893), polyhydroxymethylene monobenzylether (Preventol D2) or 1,3,5-tris (hydroxy-ethyl) hexahydrotriazine (Grotan BK) was carried out in 6 Danish out-patient clinics to evaluate guinea pig allergy test results with the same compounds. A total of 1652 consecutive patients with dermatitis were tested. The usefulness of this patch test battery was limited. There were a few positive reactions to Cytox 3522, BIT and the 2 formaldehyde releasers, Preventol D2 and Grotan BK. These reactions could not, however, be explained. The MOAHL-index (% of Male patients, Occupational cases, Atopic patients, Hand eczemas, and Leg ulcers/stasis dermatitis) for patients from the 6 clinics showed equal frequencies of male patients and atopics, but significant differences in the frequencies of occupational cases, hand eczemas, and leg ulcers/stasis dermatitis, indicating possible variations in referral patterns, use of patch tests, and/or environmental factors.