Chloracne in seven organic chemists exposed to novel polycyclic halogenated chemical compounds (triazoloquinoxalines)

Chloracne is an acneiform eruption caused though poisoning by aromatic compounds (usually halogenated) showing a specific molecular configuration. We describe an outbreak of chloracne among seven discovery chemists who synthesized novel polycyclic halogenated chemical compounds which were classified as triazoloquinoxalines, not known to be chloracnegenic. The diagnosis of chloracne, made clinically, elicited a thorough risk assessment and monitoring programme by the occupational health department. The chemists were investigated by serum excretion rates, skin sampling for Propionibacterium acnes, skin biopsy and laboratory blood investigations. Sebum excretion was normal in five cases, raised in one case and severely reduced in another. Skin levels of P. acnes were normal in all patients except for the one subject who had low sebum excretion, in whom they were undetectable. One subject had a slightly raised serum level of alanine aminotransferase. There were no other signs of systemic toxicity. Two subjects were treated with an oral antibiotic, two received topical therapy only and three required no treatment at all. The patients have had thorough health surveillance at 6-monthly and yearly intervals. In each case the chloracne mostly resolved within 18-24 months although on examination about 3 years later, five of the seven still showed minor changes of chloracne. This outbreak emphasizes the need for vigilance in discovery science. The triazoloquinoxalines were not previously recognized as being chloracnegens although their chemical characteristics were subsequently identified as being in keeping with other chemicals that can cause chloracne. Chloracne can be a difficult diagnosis to make when it occurs in a novel setting: occupational physicians and dermatologists need to be vigilant when dealing with unusual eruptions in discovery chemists.