Unsafe working conditions lead to tragedy at Massachusetts chemical plant.

The Seqens/PCI Synthesis chemical plant in Massachusetts, which has a history of safety violations, is under investigation by the Occupational Safety and Health Administration after a powerful blast killed a worker and injured four others. A former employee described the working conditions as unsafe and negligent. Massachusetts lawmakers have demanded a full accounting of the incident and the company's safety practices. The plant has had multiple explosions and safety violations in the past, and the latest incident has prompted calls for the facility to be shut down.