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Tianjin China: a reminder of human health safety

"Mina da passagem" by Leandro Neumann Ciuffo Wikimedia Commons

The explosions that rocked Tianjin China hit headlines on most news station around the world last Wednesday. The massive explosion could be felt kilometers away and was reportedly visible from space. The shockwave from the first blast was equivalent to an earthquake measuring 2.3 on the Richter scale (or three tons of TNT). The second blast was equivalent to 21 tons of TNT that was then followed by a series of smaller explosions.

With at least 70 people missing, 114 dead, nearly 700 injured, 6,000 people displaced, and 17,000 homes were damaged.

According to the BBC, the storage facility that exploded had only received a license to handle hazardous materials in May. Eight months before obtaining the license they were operating without proper documents.

There were a number of poisonous chemicals present during the blast, including:

700-ton sodium cyanide, 800-ton ammonium nitrate and 500-ton potassium nitrate

Two things come to mind: what are the uses of these chemicals and what are the environmental risks in the area?

For all three toxins, the environmental risk is short-term and thus future exposure to the chemicals is less likely due to the solubility in water. However, short exposure to high concentrations can lead to major health issues.

Sodium cyanide(NaCN) is a white crystal that is water soluble. Combined with water, NaCN produces a gas hydrogen cyanide (HCN) can be extremely deadly in low dosages. It is used primarily in mining to extract gold from ore (process explained here) but has historically been used by both the Nazi and US as a form of execution. NaCN breaks down naturally over time and the process can be sped up using hydrogen peroxide (H₂O₂) to form less dangerous reactants. Water contaminated by NaCN can be treated with bleach to remove the cyanide.

Ammonium nitrate(NH₄NO₃ or N₂H₄O₃) is a white crystal and is water soluble. It is used primarily in fertilizers but is often used in mining as an explosive due to its volatile nature. Most of the environmental risk is produced during fires in the form of poisonous gas and because of the flammable nature of N₂H₄O₃. Water systems may become contaminated but will biodegrade over time.

Potassium nitrate(KNO) is a white gray crystal. It is used most famously in gunpowder but can also be used in the process of food preservative, fertilizers, pharmaceuticals, and solar power. It is non-combustible but enhances combustion of other chemicals.

The Tianjin tragedy is a reminder of the importance of human and environmental safety regulations for storage and transport of chemicals. It is also a reminder that the desire for precious metals have impacts that go beyond simple economics and extraction affects. The processes, chemicals, and people all along the supply chain carry risks.