...Dozens of workers at a Teesside chemical plant received hospital treatment...following a leak of 4.5 tonnes of toxic chemicals...All 37 victims were employees of BASF and suffered burns, irritation to the skin and eyes, and breathing difficulties when the hexamethylenediamine (HMD) leaked from a tank...[A] spokesman for BASF said: "The cause of the event has not yet been identified and an investigation into this incident was initiated as soon as possible ..."