AN investigation has been launched following a toxic leak that left a man with serious burns.

Dozens of workers at a Teesside chemical plant received hospital treatment after suffering burns and breathing difficulties following a leak of 4.5 tonnes of toxic chemicals.

Firefighters set up a mobile decontamination unit to treat victims before they were taken to hospital.

Two were still receiving treatment this morning. The most seriously injured man was airlifted to Newcastle Royal Victoria Infirmary from the University Hospital of North Tees, at Stockton. Last night he was in a critical but stable condition.

The other is known to be suffering from facial injuries and is being treated at the James Cook University Hospital, Middlesbrough.

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.

Paramedics were called to the Nylon Intermediates chemical plant at Seal Sands Road, Billingham, at 9.45am yesterday.

Fourteen site employees were taken to hospital as a precautionary measure with a further three requiring specialist treatment.

HMD, a chemical used in the manufacture of a range of plastics, is corrosive and can be hazardous in high concentrations.

David Pedley, consultant in emergency medicine at James Cook University Hospital, said eight patients were released following minor treatment and one had been detained.

He said: "Once they were decontaminated at the site and the chemical was removed, they were treated for irritation and burns.

"Eight were released with simple treatments such as skin creams and eye ointments.

"One was assessed as needing further treatment and has been detained. He is not serious, but any burns to the face are dealt with seriously due to the possible complications.

"It is too early to assess the type of facial burns, but he will be kept under observation."

A toxicologist from Leicester University warned about the hazards the chemical poses.

Dr Andrew Smith said: "Hexamethylenediamine is very corrosive if spilt on the skin and eyes, and to the airways and lungs if breathed in.

"Long-term exposure may lead to liver and kidney damage."

Alastair Hay, Professor of Environmental Toxicology at Leeds University, said: "The chemical is freely soluble in water and, therefore, it is important that it be kept away from water courses in order to protect aquatic and marine life."

An investigation was launched to determine the sequence of events that led to the leak.

Chris Wilson, 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 and involved the Health and Safety Executive (HSE) and the Environment Agency."

A spokesman for the HSE said: "We have got inspectors on site to try to determine what caused the chemical outbreak. The investig- ation is being carried out by the Hazardous Installation Directorate, but it is too early to give any cause."

Officers from the Environment Agency are investigating whether the chemical could have entered the water system.

Steve Johnson, Billingham fire station manager, who is in overall control of the incident, said: "It is not yet known how the casualties came by their injuries.

"When mixed with water, HMD produces carbon dioxide. We put a deluge system on the tank and a number of ground monitor jets to isolate it.

"Because of the number of casualties, and other agencies involved, it was classified as a major incident."

Five fire appliances - three from Hartlepool, one from Billingham and one from Stockton - plus a decontamination unit, were sent to the site.

A paramedic trained in chemical, biological, radiological and nuclear incidents co-ordinated the decontamination. Ambulance crews from across Teesside went to the scene, as well as a major incident response unit.

Frank Cook MP, whose Stockton North constituency includes the Seal Sands plant, was in Taiwan when The Northern Echo informed him of the incident.

He said: "I am seriously concerned to hear about this and will be demanding a detailed report from BASF.

"I will get my team in Billingham on to it right away and will expect a report on my desk when I get back on Monday."

The BASF plant produces chemicals used in the production of acrylic and nylon fibres for clothing and carpets. It also makes nylon and acrylic plastics for domestic goods and the engineering and motor industries.

Emergency plans - Page 6