Everyone in the dark over extent of Roundup use
Authorities do not know how much of the chemical weedkiller glyphosate is used in New Zealand.
A United States jury recently awarded terminally ill Dewayne Johnson US$289 million (NZ$440m) in damages, after it determined Monsanto's Roundup weedkiller caused his cancer – and the corporation failed to warn him of the health hazards from exposure.
Glyphosate is the key ingredient in herbicides, the best known of which is Roundup manufactured by Monsanto.
The judgment has triggered concerns about glyphosate use around the globe, with some UK retailers considering removing the product from shop shelves.
Stuff approached the Ministry for the Environment, the agricultural chemicals lobby Agcarm and Horticulture New Zealand. All said the Environmental Protection Authority (EPA) was the agency to ask, but it replied it did not collect information about how much glyphosate was used annually.
On Monday the EPA said it had not been involved in the US court case, and was not aware of any specific evidence which was used in court.
"There is no change to the science behind our current position, which is products containing glyphosate remain safe to use when you follow the instructions on the products label," general manager of the EPA's hazardous substances group Dr Fiona Thomson-Carter, said.
Besides Monsanto, about 25 different manufacturing companies produce glyphosate-based products in New Zealand under 89 trade name products.
Glyphosate has been used in New Zealand for 42 years, and it's used on a wide range of crops, for example wheat, barley, oats and peas before harvest.
Glyphosate-based products are also commonly used for weed control on a range of rural, commercial and residential properties.
Agcarm chief executive Mark Ross said the herbicide had recorded over 40 years of safe use and been the subject of over 800 studies, all of which confirmed its safety. More than 160 countries approved its safe use.
Other than going organic, Ross said there were few alternatives to glyphosate, and they could be more hazardous and more expensive. Possible examples could be paraquat, 2-4 D, amitrole or metsulferon-methyl (escort).
Ross said it had low-volatility and degraded quickly in soil.
"Care is still needed when using crop protection products as well as many other everyday substances. It is important to use them according to label directions - keep them out of the reach of children, avoid spray drift and wear the correct protective equipment," Ross said.
The EPA said it did not know what crops the weedkiller was used on, and did not know alternatives.
New Zealand's arable industry, which is worth about $1.2 billion a year, and exports $180m worth of seeds and cereals, is highly dependent on the chemical, as is horticulture (export value $5.1b).
It is an integral part of farming systems using no tillage or minimum tillage systems.
Federated Farmers said a ban would jeopardise the country's ability to be competitive in grain and seed production.
Meanwhile, a New Zealand group of public health experts has concluded the EPA process for evaluating the carcinogenicity of glyphosate was flawed.
The experts, from Auckland and Massey universities, said there was no mention of risk assessment or "net-benefit approach" in the report and no discussion of current New Zealand glyphosate exposures.
They criticised the EPA's assessment for quoting heavily from a European Food Safety report, which they said was itself "markedly flawed" and relied heavily on "industry-funded and industry-manipulated reviews".
"Given the scientific flaws in both reports we urge that: the NZEPA report be withdrawn; the NZEPA respond to the concerns raised and for a reassessment to be conducted; and clearer process and better understanding of science be used to inform any future review of hazardous substances in New Zealand," they wrote.
In 2016 poisons expert Dr Wayne Temple and his colleague from the National Poisons Centre, Michael Beasley, carried out a review of the product for the EPA.
It followed two controversial studies, one by a World Health Organisation agency that said glyphosate was "probably carcinogenic to humans" but another said it was unlikely to pose any health risk to humans.