Wednesday, 15 November 2017

Which way for Glyphosate?

Version 1711/17

I've just done some research into the world's most commonly used herbicide - Glyphosate. Admittedly, there's many limitations on what I've done. For example, I have not looked at other than one study into the adjuvants (chemicals used in the commercial herbicide formulations to assist application) nor at the huge number of reports on food residues. Some of the adjuvants are considered to be of greater toxicity than glyphosate itself - I’ve written about these before in my Conservation News column in British Wildlife.

A complete document with references (bear in mind it's not 100% tidied up as I've run out of time to do that right now) is available, let me know if you want to see it. I'm also happy to update what I've done with missing info and to correct any errors. 

If you manage to get to the end of this blog, let me know what decision YOU would make on whether to relicense it for use in the EU - a decision which will be made at the end of this month (November 2017).

My interest in the subject is because I want to understand more about glyphosate-based herbicides (GlyBH) and their actual and potential effects on human and environmental health, including on soils. I have used Roundup® - the original formulation marketed exclusively by Monsanto until recently - personally and professionally. It’s very useful, for killing weeds growing in the patio, knackering bindweed in the allotment and extremely helpful when establishing new wild flower grassland on arable or other bare ground.

One of the claimed for ‘vital’ uses for GlyBH is in the increasing adoption of minimum tillage, which means that farmers no longer need to plough arable land, but can direct drill the next crop into soil that has been cleared of weeds using glyphosate. Minimum tillage is considered to be beneficial to soil conservation by reducing erosion by water, wind and oxidation. In the UK there is a campaign among conventional farmers, led by the National Farmers’ Union, for Glyphosate to be relicensed by the EU (#GlyphosateisVital) - a decision which should have been made November, but a qualified majority vote could not be reached on the proposal to issue a new licence for five years. The European Parliament had previously voted by significant majority to phase out the herbicide completely for agricultural use by 2022 and to ban household use immediately. A decision by the European Commission will now have to be made by the Appeal Committee by November 2017.

GlyBH have been used since 1974 and while their use has escalated across the world over the past two decades there remain significant gaps in our knowledge of the risks the herbicide poses to people, soils, air, water and nature. Research into its role and benefits, such as for rebuilding soils under minimum tillage, has also been neglected - meaning that claims on its usefulness for this purpose are not adequately supported by peer-reviewed evidence.  Making a reasoned decision on whether this useful herbicide - one which agriculture currently relies upon - and which some say is a vital tool for producing food under current ‘conventional’ farming systems (and for other purposes such as invasive weed control) - should be banned across Europe, is what might some would call a wicked conundrum.

Here's a summary of what I found out (or in some cases knew already through my work as a land management adviser):

  1. USE. GlyBH are widely used across the UK on farms, parks, gardens, along roadsides,around buildings and to keep the railways clear of weeds.
    1. Glyphosate residues are found in many samples of food consumed in the UK but are also not present in many food samples. However residues, where found, are generally well below the permitted Maximum Residue Levels.
    2. Sampled foodstuffs often contain multiple pesticide residues. We have no knowledge of the synergistic effects of these on human health.
    1. GlyBH are relied upon in conventional arable farming to destroy infestations of herbicide-resistant black grass that have arisen partly because GlyBH have facilitated changes in farming practice.
    2. Although glyphosate-resistant Black Grass is not yet a problem in the UK, many consider this is only a matter of time, especially as farmers now rely on GlyBH for conservation tillage.
    3. Glyphosate-resistant weeds are a massive problem in countries where glyphosate-tolerant genetically-modified (GM) crops have been/are widely grown. Some of those weeds are already present on UK farms.
    1. GlyBH (along with other changes, such as larger and more powerful farm machinery) have made it easy to transform previously diverse mixed-farmed landscapes, with adverse indirect and direct impacts on soil, nature and freshwaters.
    2. This transformation has also contributed to increased flooding of settlements as it has encouraged the cultivation of unsuitable land that is at high risk of water erosion.
    1. GlyBH are commonly used in ecological restoration, such as the re-establishment of flower-rich grassland on bare land, for weed control in hedge and tree planting and for killing invasive species such as Japanese Knotweed.
    2. It is currently the main tool for controlling/eradicating some non-native invasive species, such as Japanese Knotweed. If banned, other herbicides would instead need to be used to control some of the UK’s worst invasives such as Japanese Knotweed.
  6. SOIL and WATER.
    1. A recent study found residues of glyphosate and its metabolite, AMPH, present in European soils. However, there is no long term, systematic monitoring programme of this herbicide in the soil environment.
    2. Glyphosate and AMPH have been found in a large proportion of sampled water bodies, but there are no water quality requirements for the substances and no ongoing monitoring programme for them.
    3. Currently, minimum tillage practiced by most non-organic farmers is reliant on using GlyBH. There is some evidence that minimum tillage increases soil carbon and biodiversity, reduces water erosion and rebuilds topsoil and that it also reduces GHG emissions owing to the reduced amount of fuel used compared to a conventional plough-based system. However, to quantify and scientifically validate these claimed-for benefits, a systems-based long term research programme on minimum tillage systems is needed - with and without GlyBH.
    4. Evidence on the long term impacts and potential side-effects of pesticides, including glyphosate, on non-target soil organisms, is thin. A recent study found adverse impacts on the surface casting activity of vertically burrowing earthworms and the reproductive capacity of some soil fauna, plus large increases in soil nitrogen and phosphate - suggesting an increased risk of nutrient leaching to ground and surface waters. Effects on nutrient cycling had been identified previously.
    1. There are significant concerns for human and environmental health regarding the widespread and common use of GlyBH in conventional agriculture across the world.
    2. Human exposures to GlyBH are rising.
    3. Concerns for public health are not confined to potential links to cancer, that have recently been discounted by the European Food Safety Agency.
    4. Risk assessment methodology for this and other pesticides has been criticised by some scientists as being insufficiently robust.
    5. RoundupⓇ has been found to be 125 times more toxic than glyphosate while adjuvants found in GlyBH have been assessed as being 10,000 times more toxic than glyphosate itself.
    6. Recent studies have identified adverse impacts of glyphosate on honeybees.
    7. According to the European Chemicals Agency, glyphosate is not proven to be carcinogenic, mutagenic or to negatively affect reproduction (e.g. reduction of fertility or occurrence of malformations), but it can cause serious eye damage and exert toxicity on aquatic biota, with long-lasting effects
    8. Long term, systematic, field-based research is lacking that would enable us to fully understand the use, fate and impacts of GlyBH at the landscape-scale, in the environment and on people.
    9. There are calls for safety standards for GlyBH to be reviewed and updated as “they may fail to protect public health and the environment”.


  1. My biggest concern is that glyphs ate is used as a dessicant just before harvest. It does not contact soil where it might boil broken down.

    I think this is one use too far.

    1. It shouldn't be being used 'just before harvest' on food crops at the very least. The recommended break before harvesting, the harvest interval is at least seven days and up to 21 days.

  2. This is a very good summary for me. I'm personally pro-glyphosate *at the moment* - on the health side of things I just accept the WHO perspective as the arguments are too complex and riddled with conspiracy theories and known unknowns for any reliable decision to be reached I think so I'm happy to defer that to higher powers. On the environmental side, I think the benefits of glyphosate to conservation tillage are significant, and for me outweigh currently any risks. I don't think we've gained enough momentum or skills in conservation tillage for conventional systems to stick with it if they lost glyphosate. I think it would be a backwards step and we'd lose the soil health benefits (I think the benefits for pollinators & farmland birds are limited and narrow in scope, but they do help). However we don't know much about the effects of glyBH on earthworms, mycorrhiza for example, but they're probably not great, so in one sense for soil health the use of glyBH is two steps forward, one step back. BUT I would like it to be relicensed for five years, to give more time for testing of alternatives, wider uptake of conservation tillage and more understanding of effective use and appropriate mitigation of negative impacts. I think it is on borrowed time, but it's too crucial to our current farming systems to take away. What happens if we re-licence it and the EU/US DON'T, is another argument. But may be crucial.

  3. Great to have most of the issues about Glyphosate set out in one article. Thanks for producing this Sue.
    Another dilema is that the Glyphosate product Roundup Probiactive is the only herbicide product left that is licensed for use in watercourses. It is used to control invasive aquatic weeds which cause a huge biodiversity loss and flooding issues.

  4. That's a good summary and fairly balanced. I have a few comments. The study on soils found 45% had residues. I think the fact that 55% had no trace shows that it is broken down considering many of those soils were likely to have had routine applications in the past. I would expect a residue of application was recent.
    I've seen a study on earthworms showing negative effects but this used doses that were 10 times field realistic dose, not sure if this is the same study though.
    On the subject of crop desiccation which has been mentioned in the comments, I use it where weeds are growing in the crop. It actually allows me to tolerate more weeds in the crop which is good for biodiversity. By cutting down on in crop herbicides I can allow an understory of pansies, chickweed and other weeds to develop in crop knowing that if they get out of hand I can desiccated before they swamp the crop making harvest difficult. I would accept a ban on this use but only if the residues from this practice are deemed unsafe.