Methemoglobinemia: an industrial outbreak among rubber molding workers.

OBJECTIVE: This case series documents an occupational outbreak of methemoglobinemia among five steam press operators at a rubber plant. Investigative findings identified the cause as repeated exposure (through manual handling) to an adhesive containing dinitrobenzene.

RESULTS: The workers presented with yellow-stained hands and a variety of clinical manifestations. Methemoglobinemia levels obtained in the emergency room ranged from 3.8% to 41.2%. Methylthioninium chloride (methylene blue) rapidly reversed the cyanosis and alleviated associated symptoms in the rubber molding workers requiring treatment.

CONCLUSIONS: Prompt action by plant officials and subsequent investigation by National Institute of Occupational Safety and Health/Occupational Safety & Health Administration personnel resulted in the timely and successful resolution of the problem. Individual presentations, assessment, and management are discussed along with recommendations for occupational investigation and referral.