First Union is calling on the Environmental Protection Authority to ban hydrogen cyanamide immediately.
Photo: RNZ/Carol Stiles
The EPA is reassessing the use of the chemical a restricted spray ingredient used in commercial orchards.
It has received 199 submissions which will now be reviewed before a public hearing is held.
The kiwifruit industry says some orchards would be uneconomic without the spray.
But First Union co-ordinator Anita Rosenteter said hydrogen cyanamide had been banned in Europe and the US was reconsidering its use so New Zealand needed to take action now.
"We want the EPA to ban hydrogen cyanamide immediately rather than phasing it out of the next five years which it's currently proposing because evidence suggests that it's a harmful chemical for the workers who apply it, as well as potentially the surrounding communities and the environment as well.
"Studies from the European Food Safety Authority say that it's a possible carcinogen, and that operator exposure is 6433 percent of the acceptable level, even if PPE is used."
Rosentreter said workers had raised concerns with the union.
"Workers have told us it causes skin and eye irritations when they're exposed to it. And basically, they've heard that it's potentially dangerous, and that makes them feel pretty uneasy when using it."
She said the effects the chemical had on people's health outweighed the benefits it provided to the horticulture industry.
"Another point we have made in our submission is that the chemical is used as a labour management tool, enabling the kiwifruit industry to operate a regime based around casual employment.
"By encouraging fruit consistency and compressing flowering time, hydrogen cyanamide saves on labour costs and makes it easier for the industry to concentrate the period in which it does the majority of its employment."
Rosentreter said this meant workers could be procured for a shorter period of time without the guarantee of ongoing work.
"This lowers the overall wage bill because workers don't get annual and sick leave, as workers only qualify for these entitlements at six to 12 months into their employment."