A drum full of a previously unknown substance that shut down a city block in Elliott last month turned out not to be hazardous.

Pittsburgh Hazmat Chief Chuck Lenz said Thursday that the drum, found June 29 in the backyard of a residence in the 700 block of Bucyrus Street, contained concrete and sand.

The drum was labeled "potassium cyanide," which reacts with metals and other materials, and releases hydrogen cyanide gas, a highly toxic chemical that can cause asphyxiation because it interferes with the body's ability to use oxygen.

Potassium cyanide is used commercially for fumigation, electroplating and extracting gold and silver from ores.

The drum was removed from the scene by Weavertown Environmental Services, which took it to an undisclosed location.

It was tested and found to be harmless, Chief Lenz said.

The container had been found by workers refurbishing a home that had been vacant for several weeks.

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