Tianjin blast: Kiwi academic describes the chemical horror

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.

The latest reports put the death toll at 112, with another 95 missing.

The series of explosions occurred around 3.30am (NZT) on Thursday at a container storage station at the city port, causing widespread damage and injury

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

Massey University's Centre for Public Health Research's Associate Professor Deborah Read says, "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," she says.

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

An official from the Chinese Public Security Ministry's firefighting bureau told thepaper.cn, a Shanghai-based newspaper, in a telephone interview that the first team of firefighters used water in an attempt to contain the fire. But water isn't the best fire suppressant for some chemicals. Calcium carbide reacts with water to form acetylene, which can catch fire.

"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," Prof Read says.

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.