Glyphosate has got to go!   

A global movement is demanding a ban of the herbicide glyphosate (best known as the main ingredient of Monsanto’s Roundup). One of Soil & Health’s campaigns is to ban or at the very least restrict the use of the controversial chemicalJodie Bruning investigates the New Zealand situation, and the lack of scientific monitoring of pesticides in general. 

Of all the chemicals used in our environment, the one that provokes the most loathing is glyphosate. It is sprayed alongside most New Zealand roads and suburban streets, in parks and playgrounds, through our forestry plantations, and on most agricultural land. Our 100% Pure NZ is drenched in it. 

Are your children being exposed to glyphosate-based herbicides that are commonly used along roadsides? Photo: Jodie Bruning

Silent spring or ecological Armageddon? 

Recent papers have described the drastic declines in everything from birds to flying insects as nothing less than an ‘ecological Armageddon.’1 Environmental chemical pollution was identified in 2015 as a key ‘planetary boundary’ that if overreached, would not allow humanity to develop and thrive.2,3  

It’s not just glyphosate, it’s the unmonitored metsulfuron-methyl (to combat glyphosate resistance) and organosilicon applied with it. It’s other pesticides, such as triazine herbicides, banned in Europe but accumulating in New Zealand groundwater, which are yet to be analysed for co-accumulation and developmental toxicity.  

How is tourism affected? Our clean and green status? Our health? The precautionary principle exists to protect, according to UNESCO, ‘where human activities may lead to morally unacceptable harm that is scientifically plausible but uncertain.’ The published science on glyphosate is anything but certain.  

How much glyphosate do we use?  

Global glyphosate production is about 800,000 tonnes.4 Retail sales of products containing glyphosate far outstrip other herbicides, with sales 12 times more than the second-highest-selling herbicide.5  

The biggest users of glyphosate in New Zealand are probably forestry, agriculture, NZTA (NZ Transport Authority) and local councils. However, our Environmental Protection Authority (EPA) doesn’t know how much is used. In 2017 an EPA communications advisor wrote ‘We often get asked by journalists about the volume or extent of glyphosate use (which we can’t answer).’6  

Glyphosate in our food 

As well as being exposed to glyphosate sprays in the environment, many New Zealanders consume it in food every day, and potentially also in water. It’s sprayed on crops such as non-organic wheat, oats, barley and potatoes as a pre-harvest desiccant. In 2016 a third of the 60 wheat samples tested by the Ministry for Primary Industries contained glyphosate above the maximum residue level (MRL) of 0.1 mg/kg (the highest measured was 5.9 mg/kg).7  

Residues of glyphosate (or its breakdown product) are present in the numerous processed non-organic foods that contain imported ingredients from ‘Roundup Ready’ genetically engineered crops. The best way to avoid glyphosate is to eat organic food. 

How safe is glyphosate?  

Glyphosate is a biocide – it has multiple pathways of toxicity. Glyphosate damages gut bacteria, and beneficial species are vulnerable but pathogenic bacteria are resistant. It harms the immune system, depletes the body of serotonin, is endocrine disrupting and neurotoxic.4  

Glyphosate is a patented antibiotic, and has been shown to affect antibiotic resistance in recent research on E. coli and salmonella.8  

Glyphosate and cancer 

Oh, and glyphosate probably causes cancer. In 2015, 17 experts in cancer at the International Agency for Research on Cancer (IARC) determined that glyphosateits more toxic commercial formulations and the metabolite (breakdown product) AMPA, all probably cause cancer.9  

In response, our EPA initiated a review by a single toxicologist to address the basis of the conclusions of the IARC.’ The EPA review did not address the toxicity of any of the commercial formulations containing glyphosate, nor its toxic and persistent metabolite AMPA (aminomethylphosphinic acid). It also ignored oxidative stress. The review concluded that glyphosate is unlikely to be genotoxic or carcinogenic to humans and does not require classification under the Hazardous Substances and New Organisms (HSNO) Act as a carcinogen or mutagen.10  

The IARC is the gold standard of cancer determination, and its impeccable protocols prioritise published or publicly available data. In contrast, our EPA relied on predominantly unpublished industry data supplied by the chemical industry.  

A deficit of data 

It is via a deficit of data that we have ended up in a no-man’s land where glyphosate is not monitored because, as industry-supplied studies inform us, it is of low toxicity. Controversy in Europe and America is raging as it appears regulators relied not just on industry data, but also on analysis and conclusions supplied by the chemical industry.11,12,13  Europeans are demanding that regulatory studies must be commissioned by public authorities. 

Full formula assessment needed 

Assessments of agrichemicals by our EPA are based solely on one active ingredient. The chemical industry never supplies toxicity studies of the full formulation – the actual products being sold and used. Yet the HSNO Act requires the EPA to assess the substance for toxicity. If there is a second declared active ingredient (such as alkyl polyoxyethylene phosphate, which forms around 20% of Agpro’s Green Glyphosate 510), this is never considered for toxic formulation synergies.  

Of concern also are the adjuvants: chemicals included in pesticide and herbicide formulations to increase their effectiveness. These adjuvants are never tested for toxicity nor monitored. For example, Pulse Penetrant, an organosilicon surfactant, is frequently applied with Green Glyphosate 510. Organosilicon surfactants ‘probably represent the single most ubiquitous environmental class of global synthetic pollutants’ and are harmful to bees.14  No risk assessment. No monitoring. 

It is as if the environmental impact cannot be scrutinised, for fear it may damage GDP. For fear we ignite the wrath of forestry, farming or the NZTA.  

What about water? 

Our newly minted National Policy Statement for Freshwater Management has an enormous black hole in it – policymakers have ‘forgotten’ to monitor synthetic organic compounds, and particularly, pesticides. Pollution of waterways threatens the long-term viability of organic – and non-organic – producers sourcing water for livestock and food production.  

A 2017 FAO report stated: ‘Major agricultural contributors to water pollution (and the main targets for water pollution control) are nutrients, pesticides, salts, sediments, organic carbon, pathogens, metals and drug residues.’15 Yet our National Policy Statement lists only nine ‘attributes’ to be monitored in water: phytoplankton, cyanobacteria; Escherichia coli; dissolved oxygen; ammonia; nitrate; periphyton; total phosphorus; and total nitrogen. 

Glyphosate and its metabolite AMPA, are not routinely monitored in freshwater, groundwater, or drinking water. Furthermore, it doesn’t degrade as quickly as regulators claim.4  

We do not have data to demonstrate how New Zealand aquatic environment responds to the multiple assaults from chemicals that may cause developmental damage to invertebrates, fish species and other aquatic fauna. Toxic synergies from multiple chemicals are ignoredIn order to restore our freshwater systems we must transparently measure and monitor all the chemical contaminants 

In 2018 the ESR will carry out the National Survey of Pesticides in Groundwater16  – and decide whether or not glyphosate is included in the surveyOur authorities need to commence monitoring of the most prolific herbicide that is sprayed throughout New Zealand, and the chemicals (adjuvants) that routinely accompany it. Organic NZ readers, you can help! See the sidebar ‘What can you do’. 

 Manufactured ignorance and undone science 

Our regulator, the EPA, says glyphosate is ‘safe’ when used according to the manufacturer’s instructions.17 In a Listener article (30.9.17), EPA chief scientist Jacqueline Rowarth claimed the EPA takes a net benefit approach, calculating how much better off we would be with a chemical than without, and ‘making the correspondence between willingness to pay and well being comparable across different social groups. Willingness to pay what?  

In 2014 I asked the EPA what the current approval for glyphosate was based on. They directed me to a 2009 report by ERMA (now the EPA) evaluating an application by Dow Agrosciences to import or manufacture GF-1280, a glyphosate-based herbicide.18  This document showed a risk assessment approach, not a net benefit analysis. 

A net benefit analysis has never been done for glyphosate, certainly not this century. Risk assessment is simply based on toxicity studies of the active ingredient glyphosate, supplied directly by the chemical industry. Studies based on full formulation toxicity are never supplied. 

Dr Rowarth wrote that the ‘EPA’s role is to uphold and explain standards that can be defended rigorously.’19 If we really were being rigorously scientific, in the public interest, we would assess toxicity of the full formulations such as Roundup. We would publicly research exponential mixture accumulation (the ‘chemical cocktail’ effects) of glyphosate-based herbicides and other pesticides in our food, and in drinking and ground water. We would take special care with children, who consume more per body weight than adults do.  

New Zealand has no idea what our environmental exposures are. We are probably somewhere between the USA and Europe. Urine tests in the USA reveal that exposures have markedly increased.20  People with glyphosate in their urine are also more likely to be chronically ill.21  

An antiquated, linear approach to risk has left New Zealand environmental monitoring of chemicals deficient; our science ‘undone’; and a toothless regulatory environment that prioritises special interests. It’s time for science-based, transparent, moral leadership that puts the public interest, our future welfare – and that of the environment – first. 

Jodie Bruning lives with her family in Tauranga. In July 2019 she was elected onto Soil & Health’s National Council. She founded the organisation RITE: Requirement for Independent Toxicity Evaluation – a safer system of pesticide assessment.

What can you do? Contact your council 

Don’t let these long names put you off! Please contact your regional council and request they include these commonly used chemicals in (A) the National Survey of Pesticides in Groundwater, and (B) future regional fresh water sampling.  

  1. Glyphosate (CAS 1071-83-6) and its metabolite aminomethylphosphonic acid (AMPA) 
  1. Organosilicon surfactant polydimethylsiloxane (Pulse Penetrant) 
  1. The other declared active ingredient in AGPRO Green Glyphosate (widely applied to roadsides and forestry): alkyl polyoxyethylene phosphate 
  1. Metsulfuron-methyl (CAS 74223-64-6) and its metabolites triazine amine (IN-A4098); ethametsulfuron-methyl (IN-R7558). 

 Non-toxic weed management 

  • Weeds turned before seeding may improve carbon, soil quality and increase nutrient profile. 
  • Weeds may provide beneficial nutrients to livestock. 
  • Longer grass length will stop Onehunga weed (prickleweed) seeding and making prickles. 
  • Longer growth habits (or less restrictive service levels by councils) can reduce time required in weed management and council (and therefore taxpayer) expenses. 
  • New technologies (e.g. electrothermal; cropping machines Harrington’s Seed Destructor and Seed Terminator; steam with biodegradeable surfactants). 
  • Protective mulching can reduce seedling quantities. 
  • Read: Pesticides Action Network Europe October 2017 report: Alternative methods in weed management to glyphosate and other  

Further reading 

  • Bruning J, Browning S. 2017Public Health Concern: Why did the NZ EPA ignore the world authority on cancer? Green Party of Aotearoa New Zealand.  
  • Watts MA et al 2016. Glyphosate Monograph. PAN International. 
  • New Zealand National Policy Statement for Freshwater Management 2014. Updated August  
  • B Humphries and M Close. 2014. National Survey of Pesticides in Groundwater. ESR.   


  1. Carrington, D18 Oct 2017. Warning of ‘ecological Armageddon’ after dramatic plunge in insect numbersThe  
  2. Steffen, W et al2015. Planetary boundaries: Guiding human development on a changing planet. Science. 347(6223).  
  3. Rockström et al. 2009Planetary boundaries: Exploring the safe operating space for humanity. Ecol. Soc. 14(32)  
  4. Watts MA et al, 2016. Glyphosate Monograph. PAN International.  
  5. Environmental Risk Management Authority Monitoring Report 2011.   
  6. Correspondence from the EPA to Steffan Browning, 16.6.17  
  7. Kurenbach, B et al. 2017. Herbicide ingredients change Salmonella enterica svTyphimurium and Escherichia coli antibiotic responsesMicrobiology. 
  9. IARC Working Group. 2015. Glyphosate. In: Some organophosphate insecticides and herbicides: diazinon, glyphosate, malathion, parathion, and tetrachlorvinphosIARC Monograph Program, vol  
  10. Temple, W. 2016. Review of the Evidence Relating to Glyphosate and Carcinogenicity. EPA.  
  11. Neslen, A. 15 Sept 2017. EU report on weedkiller safety copied text from Monsanto studyThe Guardian   
  12. Burtscher-Schaden H et al. 2017. Glyphosate & Cancer: Buying Science. GLOBAL 2000/Friends of the Earth Austria.  
  13. Brown V & Grossman E. Nov 2017. How Monsanto captured the EPA (and twisted science) to keep glyphosate on the market. In These Times. 
  14. Chen et al. 2017. Are organosilicon surfactants safe for bees or humans? Science of the Total Environment, 612.  
  15. Mateo-Sagasta, J & Marjani Zadeh, S. 2017. Water pollution from agriculture: a global reviewFAO.  
  16. Humphries, B and Close, M. 2014. National Survey of Pesticides in Groundwater. ESR.   
  17. How glyphosate is regulated in New Zealand. 2017. EPA.  
  18. ERMA. 2009. Evaluation and Review Report Application for Approval to Import or Manufacture GF-1280 for Release.  
  19. Rowarth, J. May 2017. Role to Change Public Perception. AgCarm Newsletter.  
  20. Mills et al. 2017. Excretion of the herbicide glyphosate in older adults between 1993 and 2016. JAMA 318(16).  
  21. Krüger M, et al. 2014b. Detection of glyphosate residues in animals and humans. J Environ Anal Toxicol 4(2).