Friday is the final day for the public to have its say on the proposed changes to the maximum residue limits of insecticides, pesticides and animal medicines that end up in our food.

New Zealand Food Safety proposed a raft of changes to these maximum residue limits, including those of the world's most common herbicide, and here in New Zealand too, glyphosate, which is the active ingredient in weedkillers such as Round Up.

The MRL was proposed to increase 100 times the current 0.1 milligrams per kilogram in pre-harvest weed control of wheat, barley and oat grains to 10 milligrams per kilo.

Another proposed increase was 6 milligrams per kilogram as a pre-harvest drying agent for pea crops.

Federated Farmers' arable vice-chairman Andrew Darling of South Canterbury, said glyphosate was an "incredibly useful tool" for the whole farming sector, as well as arable.

But he said it was not used "willy-nilly" due to its cost, and farmers adhered to good agricultural practices around its use and followed manufacturer suggestions too.

However, he said most farmers did not see the need for levels to jump so high.

"The current MRL limit on glyphosate, for example, was probably just a default setting," Darling said.

"And some survey samples were done about five years ago, I mean the majority were under that 0.1 percent of what it currently is at, with only a handful being over.

"We're well below international MRL rates, so a small lift wouldn't be a problem," he said.

"But from a Federated Farmers point of view, we struggle to see why it needed to be increased to 100 times what's been from 0.1 percent to 10 percent when we're well underneath that."

A petition started by digital marketing specialist Jade Steel of Bay of Plenty gained 16,500 signatures within a fortnight in opposition to raising the glyphosate limits.

She said it was hard to avoid the presence of glyphosate in food.

"So far, everybody I've noticed who's seen [the petition] and commented and shared it have been really shocked that this is even happening like people cannot believe that this is happening," she said.

"I've been trying to avoid glyphosate in my food for years now and just the fact that they're trying to raise the limits is terrifying."

Glyphosate has been at the centre of many scientific studies in recent years to understand long-term health effects from exposure.

New Zealand Food Safety's consultation document said MPI determined the use of glyphosate for crops carried out with good agricultural practice was "unlikely to pose health risks."

Its deputy director-general Vincent Arbuckle said once consultation was completed, it would consider changes to the Food Notice by either progressing changes as proposed, amending them or withdrawing them altogether if further work was needed.

In October, the Environmental Protection Authority decided not to re-assess the use of glyphosate following a request from advocacy group the Environmental Law Initiative.

Public consultation close at 5pm on Friday.

-RNZ