Herbicide sprays, including use of glyphosate, are the primary method used by city council contractors to control weeds and vegetation.
Some long-term health and environmental concerns surround glyphosate, the active ingredient in products such as Roundup, but they are disputed.
The city council requested a review in July last year on the use of herbicides, especially those containing glyphosate, and a report is to be discussed by the strategy, planning and engagement committee today.
Glyphosate is the most widely used herbicide in the world.
It has been under heightened scrutiny since 2015, when the World Health Organisation’s International Agency for Research on Cancer classified it as "probably carcinogenic to humans".
Bayer AG, which bought Roundup manufacturer Monsanto in 2018, denies there is any valid evidence that it causes cancer.
However, the product is to be pulled from shop shelves in the United States this year, after extensive litigation.
New Zealand’s Environmental Protection Authority considers glyphosate to be safe if applied in accordance with regulations and guidelines.
The report for the city council said industry and staff experience showed herbicides were the most effective method for controlling weed and vegetation growth.
Contractors took a precautionary approach to manage risks, including using protective equipment and managing spray drift, the report said.
The council used glyphosate on road shoulders, surface water channels, lawn edges, footpaths and around buildings.
About 3500 litres a year had been used in connection with transport networks and 1625 litres for parks and recreation areas.
The city council has trialled thermal techniques such as steam and hot water.
However, these were determined to be less effective, because they had to be applied two to four times more often than herbicide sprays.
Organic herbicides were "proven by industry experience to be less effective than glyphosate products", the council report said.
The Christchurch City Council’s policy is to use glyphosate sparingly.
