Occupational allergic contact dermatitis caused by benzisothiazolinone in printing ink and soap

Benzisothiazolinone (1,2-benzisothiazolin-3-one or BIT) is an antimicrobial agent used as a preservative in multiple water-based solutions, such as glues, cleaning agents, polishes, paints, varnishes, and hardeners (1). The use of this preservative is allowed in household and industrial products (2); however, its use in cosmetics is not allowed (3). It may occasionally be present in PVC gloves (4) and (imitation) leather shoes (5, 6). BIT has been recognized as an allergen since 1976 (2), owing to its use in many different occupations, for example carpet, water-softener, air-freshener and paint manufacturing, in painters, pottery workers, paper makers, woodwork teachers, plumbers, metal workers, and laboratory technicians (4). In addition to reports of multiple cases caused by direct skin contact, systemic skin reactions following airborne exposure to BIT have been described (2). Two previous reports concerned reactions to BIT in the printing industry, namely in a silk-screen printer (7) and a lithographic printer, respectively (8). In the latter case, gum arabic preserved with BIT was used to coat the printing roller. However, allergic contact dermatitis in professional printers caused by exposure to BIT in printing ink itself has, to our knowledge, not been previously described. Here, we present 2 such cases.