Objective: 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.
Methods: Workplace investigation involved interviews with the asthma cases, review of medical records, and medical and industrial hygiene surveys in the plant.
Results: 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.
Conclusions: 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.