The main union at New Caledonia's SLN nickel company has issued a strike notice.
The Soenc branch at the smelter says the strike threat is over the lack of safety and the pollution at the Noumea plant.
It says the premises are old and there is a feeling that the French parent company Eramet doesn't want to invest into an upgrade of the facilities.
The union has accused the management of being irresponsible, leaving the site in a filthy state.
This comes only weeks after one worker was seriously injured in a furnace explosion.