The authors conducted an investigation of a cluster of eight new-onset asthma cases identified in a chemical plant through the Sentinel Event Notification Systems for Occupational Risks (SENSOR) program.
Workplace investigation involved interviews with the asthma cases, review of medical records, and medical and industrial hygiene surveys in the plant.
Altogether, 11 work-related asthma cases were identified among the plant workers—approximately 10% of the workers exposed to the potential causative agents: 3-amino-5-mercapto-1,2,4-triazole (AMT) or N-(2,6-difluorophenyl)-5-methyl-[1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonamide (DE-498; trade name Flumetsulam). Of these cases, six had physician-diagnosed occupational asthma (OA) based on work-related respiratory symptoms and nonspecific bronchial hyperresponsiveness (NSBH), and of these, three had work-related expiratory peak flow changes.
The findings of this investigation, together with findings from concurrent animal studies, suggest that this outbreak of new-onset asthma was associated with exposure to AMT.
Clinical Significance: A cluster of eight new-onset asthma cases was identified in a chemical plant through the SENSOR program. Subsequent workplace investigation identified AMT, used in the production of a herbicide N-(2,6-difluorophenyl)-5-methyl- [1,2,4]triazolo[1,5-a]pyrimidine-2-sulfonamide, as the most likely causal agent.