A burglar may have forced access to a commercial fridge, but this was yet to be determined.
A neighbour said he believed that the refrigerator contained 1080 but, after questions from the Horowhenua Chronicle, McCartney confirmed on Tuesday 1080 was held in a secure pesticide store in the building, though not in the fridge.
He said Horizons was still taking an inventory of items after the fire, but "all run-off associated with putting out the fire was contained onsite and there are no environmental or health concerns".
Skoglund said police were talking to the Horizons fire security manager and the last worker on the premises before the burglary.
"There was a fire around the area of a single quad bike inside the building," he said.
"We are yet to link the burglary with the quad bike that was set on fire."
REMAINS of Horizons signage sits in a pile of ash and charred windows.
McCartney said it was not yet clear how much the arson would cost ratepayers but said the council was insured."There has been considerable damage. Fortunately, our boat that undertakes monitoring on Lake Horowhenua was not onsite and will be able to continue business as usual," he said.
Three pest control staff work out of the Levin depot. The depot is also used for storage.
The front of a Horizons vehicle, left melted by a fire that tore through their Levin depot last week.