The lack of oversight is apparent in the questions being asked about what was being stored in Tianjin warehouse. Chinese authorities say they aren't sure, as the facility's managers provided "insufficient information."
Military inspections at the blast site Sunday revealed "several hundred tons of cyanide material" at two locations, said Major General Shi Luze. Authorities are checking customs records for more clues as to exactly what was being held.
The "cyanide material" was sodium cyanide, a highly toxic substance used to extract precious metals in the mining industry, among other uses.
"Sodium cyanide is a very toxic chemical. It would take about a quarter of teaspoon to kill you. Another problem with sodium cyanide is that it can change into prussic acid, which is even more deadly. So the whole business is trying to clean up this mess is difficult," chemical risk consultant David Leggett told CNN.
Environmental group Greenpeace said it believed other dangerous chemicals stored at the site included toluene diisocyanate and calcium carbide, citing a local monitoring station.
Leggett said he found it "hard to believe" there were only a handful of different types of chemicals in the Tianjin warehouse: "I would have expected a lot more than that," he said.
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Authorities had earlier said that the warehouse contained calcium carbide, potassium nitrate and ammonium nitrate.
Calcium carbide is used in the production of PVC plastic, while the other two chemicals are used in producing fertiliser and dynamite.
There were unconfirmed reports that the warehouse contained 700 tonnes of sodium cyanide, stored in wooden boxes or iron barrels. The chemical is used in the mining industry, among other uses. Police on Saturday confirmed the presence of an unspecified quantity of it near the site.
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In sodium cyanide's case - yes, very much so. US government health experts say it can be "rapidly fatal" if inhaled or ingested. It is soluble in water - raising concerns in some Chinese media that it may have entered drain water - but its dust is also easy to inhale.
It releases the highly poisonous gas hydrogen cyanide when dissolved or burned.
Potassium nitrate can cause breathing problems and damage to kidneys, while ammonium nitrate can be toxic when burned.
Calcium carbide can be harmful if touched or breathed, and doctors recommend immediately washing affected areas.
One image widely circulated on the Chinese micro-blogging site Weibo, said to be from the disaster site, appeared to show a chemical burning when water was poured on it.
"With such a large fire, inevitably the plume of toxic fumes that have been dispersed could have devastating effects to the public in the future," says Shane O'Carroll, a chemical safety specialist with Chemstore, a British hazardous materials company.
Mr O'Carroll says sodium cyanide running off into groundwater systems could pose a public health risk, and he said people in Tianjin should consider drinking only bottled water.
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Reports that 700 tonnes of sodium cyanide were stored at the warehouse that exploded sparked concerns that it could contaminate the city's drinking water.
"If this issue isn't addressed soon, it could be even worse than the blast itself," said Weibo user Tao Weng WT, in a censored post.
Xinhua and Global Times on Saturday reported that cyanide content in waste water in the affected area was more than double the normal limit.
On Monday, officials said that three waste water discharge monitoring stations within the evacuated area saw excessive levels of cyanide, with one station recording a level 27.4 times the normal limit, reported People's Daily.
But authorities have stressed that the area is sealed off and hazardous material was contained at the site.