Chemicals at Tianjin explosion site – expert reaction

The exact cause of the huge explosions that rocked the Chinese port city of Tianjin remains a mystery for now, but chemical experts on the ground are assessing the situation.

Credit: Wikimedia / Eristic-??The series of explosions occurred around 3.30am (NZT) last Thursday at a container storage station at the city port, causing widespread damage and injury. Latest news reports put the death toll at 114 dead, with 70 still missing.

According to initial reports from the Tianjin Tanggu Environmental Monitoring Station, hazardous chemicals stored at the site may include sodium cyanide (NaCN), toluene diisocyanate (TDI) and calcium carbide (CaC2).

The SMC collected the following expert commentary.

Associate Professor Deborah Read, Centre for Public Health Research, Massey University, comments:

“It is still unclear what hazardous substances and chemical safeguards were present in the Tianjin warehouse. Three highly hazardous substances have so far been reported – sodium cyanide, calcium carbide and toluene diisocyanate. Inhaling any of these chemicals causes breathing difficulties which may be fatal.

“Sodium cyanide releases hydrogen cyanide gas on contact with acids or water. Hydrogen cyanide interferes with the body’s ability to use oxygen particularly affecting the brain, heart and lungs and can rapidly lead to death.

“Contact of calcium carbide with water can result in  fire and explosion.  Calcium carbide is corrosive to skin, eyes and airways and can cause fluid in the lungs (pulmonary oedema).

“Toluene diisocyanate irritates eyes and airways and can cause asthma and fluid in the lungs (pulmonary oedema).

“Other toxic chemicals will also have been formed by fire. Apart from burns and injuries from glass and other debris, the survivors are likely to have respiratory effects. Nearby residents may also experience eye irritation and respiratory and psychological effects. Ill-health among residents will depend on the extent of their exposure before they were evacuated and factors like their age and pre-existing health status.

“In New Zealand the Hazardous Substances and New Organisms Act 1996 and the Resource Management Act 1991 cover the safe transport and storage of hazardous substances.”