Fumigant chemical lost overboard from a ship about 200km offshore from Opotiki last week might wash ashore in the Gisborne or Bay of Plenty districts and should not be touched.
The metal canisters contained a dangerous fumigant, said Bay of Plenty Regional Council manager maritime operations, Reuben Fraser.
The MVGladiator was en route from Napier to China in rough seas on Wednesday night when a box containing 14 flasks of aluminium phosphide (ALP) washed overboard. Each flask contains chemical used for treating wood products, weighs 1.5kg and has a red and white label with the name Genfume AP and poison warnings.
There was only a small chance that the canisters had entered the Bay of Plenty's waters, as prevailing currents and winds were likely to take them further out to sea, he said. However, residents needed to be aware that they could wash up on the beaches.
Gisborne District Council spokeswoman Toni Lexmond said there was only a small chance the canisters would appear in the district but people should be aware.
"With school holidays this week, it's vital that parents warn children playing on the beach not to touch the canisters, since they are small enough to attract children's interest."
People exposed to even low levels of the chemical will feel ill and it can also cause ringing in the ears, fatigue, nausea and pressure in the chest. High concentrations can be fatal.
The chemical can irritate skin and eyes and it is toxic if swallowed.
Mr Fraser said the regional council was notified only yesterday morning about the loss of the canisters.
The box of canisters had been placed in the ship's storeroom but the door was left open when the ship sailed. During rough weather, water washed into the storeroom, washing the flasks and other items into the sea.
"ALP is safe in the flask and is very difficult to open. If the flasks wash up we will collect and dispose of them," he said.
