Chemicals found in common household products are up for priority review by the Environmental Protection Authority (EPA), but controversy surrounds the exclusion of products already banned in other countries.
The EPA launched a new risk assessment model yesterday, which aimed to provide a universal approach to identifying whether a chemical was a hazardous substance.
The agency screened over 700 chemicals and released a list of 40 chemicals that were designated a priority for review.
But widely-used pest-control toxin 1080, and glyphosate - which is found in Monsanto's widely-used Roundup weedkiller - were deemed not risky enough to be reassessed. The agency said there was no ''evidential" basis to consider the chemicals high-risk.
France banned the use of glyphosate outright last year, citing a link to cancer and other illnesses.
Twelve other countries have banned the substance, with Germany currently finalising draft legislation to also end its use.
The synthetic version of sodium fluoroacetate, known commercially as 1080, is also banned in several countries, including Brazil.
Many of the chemicals that do make the EPA list have not been assessed since first released on the market decades ago.
One chemical considered a very high-risk to human health and the environment was cypermethrin, found in fly-sprays and ant-killers. It is considered high-priority, appearing in the list's top seven.
EPA chief executive Allan Freeth said just because a chemical was placed on the list did not necessarily mean restrictions or bans would follow.
"We'll be approaching each of those chemicals with fresh eyes, putting it through a systematic process," he said.
"Some may be removed from the shelves, others may simply be restricted and others may be left alone [if] we're happy with the way they're being utilised."
But not everyone at the announcement was satisfied with the EPA's new approach.
Sustainability Council of NZ executive director Simon Terry said it was a waste that the EPA was reviewing products already banned in other countries where a trusted authority had ruled products as unsafe.
"This is a fundamentally broken system because there should be an automatic deletion of those chemical where a trusted overseas regulator has already decided these are unsafe," he said.
"If, for example, an overseas jurisdiction has already declared the chemical to be banned because it's unsafe, it would cost New Zealand a million dollars or more per chemical or group of chemicals to get those same substances off the market."
Brodifacoum, a chemical used in poison to kill rats and possums, also makes the priority list. It is available for home use under the name Pest-Off.
Chief executive of Orillion, the firm that produces Pest-Off, William McCook, said he encouraged greater restrictions around the use of brodifacoum.
"In other countries internationally, there are usually greater controls on that in terms of who can purchase it and also, restrictions on how the products are used so I think it is quite timely for New Zealand to have a look at all of those things," he said.
"In New Zealand we don't have a lot of controls on some of the retail products... I think it is the responsible thing to do and it should perhaps not just be home use but all use."
The Department of Conservation (DOC) also uses brodifacoum as rodent eradication on off-shore islands.
In a statement, the department said it was aware of the risks and had taken steps to reduce its use.
"DOC recognised the issue in 1998 and by 2000, DOC moved to immediately restrict the use of brodifacoum on the mainland, particularly where there were pigs and deer exposed, to eliminate pathways to humans and reduce pathways to non-target species," it said.
However, DOC said that brodifacoum was "one of the essential tools in our pest control toolbox" and it "would defend the use of brodifacoum for offshore island eradication of rodents".
In August Associate Environment Minister Eugenie Sage requested the agency put Roundup on its priority review list.
However, Mr Freeth maintained Roundup was not considered to pose a greater risk than the 40 chemicals up for reassessment.
"One of the first things people are going to say when they see the list, as indeed some elected representatives asked, where was 1080, where was glyphosate," he said.
"None of them occur in the first 40 chemicals of concern and that's on evidential and risk-based process and no doubt we'll have to continue I suspect to defend that position but we do so with a pretty strong robustness."