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New-Onset Asthma Associated With Exposure to 3-amino-5-mercapto-1,2,4-triazole

Hnizdo, Eva PhD; Sylvain, David MSc, CIH; Lewis, Daniel M. PhD; Pechter, Elise MPH, CIH; Kreiss, Kathleen MD

Journal of Occupational and Environmental Medicine: December 2004 - Volume 46 - Issue 12 - p 1246-1252
doi: 10.1097/
Original Articles

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.

From the Division of Respiratory Disease Studies (Drs. Hnizdo and Kreiss), the Division of Surveillance, Hazard Evaluations, and Field Studies (Mr. Sylvain), and the Health Effects Laboratory Division (Dr. Lewis), National Institute for Occupational Safety and Health, Morgantown, West Virginia; and the Occupational Health Surveillance Program, Massachusetts Department of Public Health, Boston, Massachusetts (Ms. Pechter).

Address correspondence to: Eva Hnizdo, PhD, National Institute for Occupational Safety and Health, MS H-G900.2, 1095 Willowdale Road, Morgantown, WV 26505; E-mail:

©2004The American College of Occupational and Environmental Medicine