Update: As the white substance identified as “sand” by Norfolk Southern railroad dissolved into the railroad tracks in Old Metairie Wednesday, the state Department of Environmental Quality said the material is in fact a calcium compound.

The non-toxic substance, which apparently dropped from a railcar on Christmas Eve, was turning into a sticky sludge Wednesday morning after the overnight rain.

DEQ spokesman Greg Langley said the department sent someone out to check on the material and that the railroad is expected to clean it up.

The railroad said Tuesday that the substance was sand, only to come back the next day after further inquiry and say the substance is "sugar."

Original cutline: Motorists have been wondering about the white granular substance left on the Norfolk Southern train tracks through Old Metairie on Christmas Eve. Railroad spokeswoman Susan Terpay said Tuesday that the substance, shown here where the tracks cross North Labarre Road near Airline Highway, is sand dropped from a railcar and is not hazardous. She said many railroads share the tracks and the railcar in question was not a part of a Norfolk Southern train.

Advocate staff photo by MATTHEW HINTON

The state Department of Environmental Quality said Wednesday that the white substance dropped along railroad tracks in Old Metairie over the weekend is a nontoxic calcium compound.

The Norfolk Southern railroad, which owns the tracks, had identified the substance on Tuesday as sand. On Wednesday, that claim became increasingly dubious, with the material starting to dissolve into a sticky sludge after overnight rain. The railroad then amended its response, saying that the material was sugar.

But DEQ, which had been contacted by nearby residents and The Advocate, sent someone out to test the material and determined it was neither sand nor sugar.

Whatever it is, officials said the substance was inadvertently released from a gondola-style railcar, which unloads product from its underside, on Dec. 24.

Norfolk Southern said Tuesday that the substance did not come from one of its railcars. But DEQ spokesman Greg Langley said the railroad will be expected to clean up the spilled substance.

Follow Chad Calder on Twitter, @Chad_Calder.