As Auckland Council does a U-turn on the use of a problematic herbicide on suburban streets, Pat Baskett looks at why we need to pay close attention to the issue

Auckland City Council has changed its mind. Last week’s meeting of the Environment Committee failed to pass a motion that would have mandated the use of glyphosate for weed control on suburban streets everywhere. Local boards, some of whom have been using steam control and other methods, will be able to continue to do so.

Glyphosate, the key herbicide in Roundup, has been used ubiquitously for 40 years and over that time nothing has quelled the controversies surrounding its effects on both human and soil health. The discussion has recently been …. distorted, some would say, by the expiry of the patent which brought cheaper versions onto the market. This was one of the budget-depressed council’s reasons for wanting it used everywhere.

The economics of the issue, along with glyphosate’s controversial health effects, were disputed by the large contingent of people who gathered outside the Town Hall before the Council meeting. Led by For the Love of Bees chairperson Sarah Smuts-Kennedy, they included John Gillan who chairs North Shore’s Kaipatiki Local Board.

They were equipped with a lengthy list of comparative costings showing flaws in the Council’s economics, and a comprehensive analysis of the current science surrounding glyphosate.

What they were asking for, given glyphosate’s chronically controversial reputation, was for the Council to act on the precautionary principle and withdraw its use everywhere. The line followed by the Council was that of the product’s producers – it’s safe when used according to the instructions on the label.

The chemical’s history is interesting. It was first discovered by a Swiss scientist in 1950 but its herbicide properties were developed by Monsanto scientist John Franz in 1970.

Glyphosate is a strong chelator and was originally used to descale water pipes and boilers. Chelation means that minerals combine with an agent and are precipitated out. In medicine, chelating agents are used to remove toxic metals from the body.

One story has it that Franz discovered that, where waste water from the de-scaled pipes had been discarded, every plant died. Presto, glyphosate became, in 1971, the first non-selective weed killer – whatever plant it touches dies (give or take a few exceptions and some that have become resistant).

Glyphosate is generally touted by users as “a safe nasty”. Its mode of action has a different emphasis according to your source. The standard explanation is that it works systemically by acting on enzyme systems and inhibiting an amino acid metabolism that exists only in plants. This enzyme disruption occurs when glyphosate starves the plant of minerals and encourages the growth of soil pathogens that then attack the weakened plant, killing it.

The emphasis for soil scientists is its action as a chelator, in both plants and soils neutralising minerals such as manganese, cobalt, iron, zinc, copper etc, all of which are essential to physiological functions. Soil scientists claim it kills beneficial soil microbes and, via the food we eat, similar microbes that exist in the human gut.

Beekeepers around the world have long been suspicious of glyphosate’s effects on bees but their fears have mostly been no more than murmured.

The genetic engineering of some staple crops such as soy, to make them resistant to it, allows the stuff to be sprayed over large areas to kill weeds. Grain crops are often sprayed again to facilitate harvest, in the practice known as “brown down”. So-called super weeds have emerged requiring super doses.

In New Zealand, research by proponents of regenerative agriculture shows that in many areas our soils are already depleted by the excessive use of urea fertilisers and nitrate inhibitors. Stop using glyphosate, they say. Instead, use cover crops and mulches for weed suppression and soil enrichment.

Some scientists have serious questions about its claimed biodegradability. They say this depends partly on what you’re looking for – which metabolites – and on multiple factors, including soil composition and temperature. The variation is wide – residue has been found to last only a few days or several months or even a year. The average half-life in waterways is also said to vary from a few to 90 days.

Globally, glyphosate is the most widely used ingredient in herbicides, including in New Zealand. It appears in more than 90 different products, of which Roundup is the best-known. If you want to avoid it, research the product you’re buying.

But its popularity could be waning, helped no doubt by its classification in 2015 as a “probable human carcinogen” and by three court cases last year in the USA in which Monsanto paid huge compensation to people who claimed glyphosate was a factor in their cancer.

Our Environmental Protection Authority has this to say on glyphosate as a carcinogen: “Other things that fall under the same classification include hot drinks (over 65 degrees C) and acrylamide – which are the crispy burned proteins from the barbecue or chips.”

We are, they assure us, “in alignment with the vast majority of regulatory bodies around the world – including in the European, the United States, Australia and Canada – which agree that glyphosate is unlikely to cause cancer”.

Nevertheless, there are at least countries with partial bans or restrictions limiting use. The Europe Union had decided in 2017 to begin restrictions and to ban it completely in 2022. Then came an about turn with an extension of five years to its licence. But individual countries, as well as individual cities and regions, have made their own decisions about its use.

France voted against that extension and President Emmanuel Macron has said its use will be banned in 2021. France has a heightened awareness of the dangers of endocrine disrupting chemicals and this year announced an official strategy to compile a list of products which contain them.

Endocrine disruptors are substances that interfere with our hormonal system and prevent the development of natural hormones. They are considered especially harmful to pregnant women. Glyphosate could be at risk of appearing on the list since studies have shown it to inhibit the development of testosterone in rats.

Austria had been about to impose a ban but this was stalled recently with a change in government. Germany has begun a phased programme of reduced use, leading to a ban in 2023. It can’t be used in domestic gardens or on the edge of farmers’ fields.

The reason for the restrictions is interesting. They are said to be part of “an insect conservation programme”. Beekeepers have long been suspicious of the herbicide’s effects on bees but their fears have mostly been no more than murmured.

Maybe the focus on cancer prevents investigation into a wide range of environmental effects and of ailments and chronic health conditions for which people may have an equally wide variation of susceptibility. Maybe we don’t yet have the means of measuring and analysing these things. Maybe we should pay more attention to the health of our soils.

Maybe we shouldn’t use it where children play.

The disasters of DDT and thalidomide are still within living memory.

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