Glyphosate, The World’s Favourite Herbicide

Glyphosate-based herbicides are bee-killing global pollutants of groundwater, rivers and surface water. More recently glyphosate has been detected in rain. The latest research reveals that glyphosate damages the beneficial bacteria in the gut of the honeybee, making them prone to to deadly infections.

Previous studies have shown that pesticides such as neonicotinoids cause harm to bees, whose pollination is vital to about three-quarters of all food crops. Glyphosate works by targeting an enzyme only found in plants and also bacteria.

Glyphosate and dicamba (another widely used industrial herbicide) increase the rate of antibiotic resistance development in bacteria by a factor of up to 100,000 times faster than occurs without the herbicide, adding to a growing body of evidence that herbicides used on a mass industrial scale, but not intended to be antibiotics, can have profound effects on bacteria, with potentially negative implications for medicine’s ability to treat infectious diseases caused by bacteria.

Research by the International Agency for Research on Cancer (IARC), the World Health Organisation’s cancer agency, says glyphosate made by agrobusiness company Monsanto, was “classified as probably carcinogenic to humans”.

I wrote this piece last year for The Organic Gardener magazine in response to an enquiry from a gardener who’s partner likes spraying glyphosate, the world’s favourite herbicide.

Glyphosate is the active ingredient in a range of proprietary herbicides. There are a variety of formulas, additives, strengths and trade names. All products containing glyphosate are prohibited from use in organic gardens.

Thanks to over reliance on this herbicide, weeds across the world have developed resistance. A super-strength formula is now sold. You can buy glyphosate with 680 grammes per litre of glyphosate instead of the 360 g/L strength…great for those hard to kill weeds says the advert.

However, the latest study at the University of Texas (USA), shows that glyphosate damages the microbiota that honeybees need to grow and to fight off pathogens. The findings show glyphosate, the most used agricultural chemical ever, may be contributing to the global decline in bees, along with the loss of habitat.

One off use

I admit that in certain circumstances and where specific weeds cannot be manually removed, then glyphosate is an option for one off control.

For example, at the Royal Botanic Gardens, Sydney, a systemic herbicide was essential to stop repeated regrowth of African olive trees. These trees were growing thickly in the steeply sloping, rocky sides of Woolloomooloo Bay. As part of the Woolloomooloo Bay revegetation project, staff abseiled down the slopes, injecting the olive trunks with herbicide.

It took years for these olive trees to decay, and during that time their dead roots stabilised the soil and their dead branches made great perches for seabirds.

Another example where a systemic herbicide may be necessary is where running bamboo is invading the banks of a creek. By painting the stumps after removing the culms, a systemic herbicide reduces the risk of bank erosion while the bamboo dies, rots and is succeeded by native vegetation.

In both instances – a steep, rocky, harbour-side slope, and a fragile riparian habitat – complete excavation is impractical. In such cases, one off weed control to facilitate bush regeneration is an acceptable, non-organic control.

Routine use

The risk to human, animal and environmental health stems from the routine, widespread use of glyphosate in an ever increasingly concentrated form.

So much has been written on this chemical, I’m drawing from the website of The Soil Association (a campaigning British charity that created the first organic standards) which seems to have the simplest and shortest of explanations.

Robert Kremer is a microbiologist with the US Department of Agriculture’s Agricultural Research Service, and an adjunct professor in the Division of Plant Sciences at the University of Missouri. His and other scientists’ research has found that glyphosate:

1 Increases fungal root diseases in crops;

2 Locks away manganese, an essential micronutrient (trace element) plants require for healthy growth;

3 Can be toxic to rhizobia, a bacterium that converts atmospheric nitrogen into nitrates on certain plant roots. This renders the cultivation of legumes, which would normally add nitrogen to the soil, useless for that purpose.

Glyphosate-based herbicides are now major global pollutants of groundwater, rivers and surface waters. More recently it has been detected in rain in Canada and the USA. Glyphosate was first detected in the rain in Belgium in 2004. This is likely to be more widespread if more countries complete testing. I’m glad I decided to filter my rainwater using four methods in 2003.

Paul Capel, head of the agricultural chemicals team at the US Geological Survey, and co-author of a study into glyphosate, published evidence of glyphosate in rain in the USA2, 3. “The real significance of this study is the documentation that it is present in the streams year round in warm areas where it is used on crops from spring to fall…“It is also present most of the time in the air and rain most of the time”…“glyphosate was found in every stream sample examined in Mississippi over a two year period and in most air samples taken”.

Glyphosate applied on plants and soil can bind with colloids – loam and clay soils being the most colloid-rich soil types. Contaminated colloids then pollute surface water indirectly as sediment in runoff, entering waterways and, by wind erosion,  the atmosphere. Glyphosate is routinely sprayed on aquatic weeds.

breakdown products of a glyphosate molecule

Glyphosate contributes to toxic algal blooms. The chemical compound we call glyphosate breaks down. As this happens, it releases a burst of phosphorous, a plant nutrient. Phosphorous pollution is most significant where sediment is deposited as silt, and silt accumulates in estuaries, sea grass meadows, coral reefs and lakes.

Contrary to advertising, glyphosate persists in soils longer than manufacturers will admit. Studies have found that its degradation in soil is slow, especially when it is applied in autumn. Cool conditions extend this chemical’s life.

Leaching enables glyphosate to contaminate soil down to one metre below ground level, another surprise the manufacturers left for independent research to discover.


It is very important that gardeners – whether organic or not – understand that when a chemical is registered as being ‘safe’ for use, registration only covers the active ingredient. When glyphosate was registered for use, no equivalent research was done for any of the additives, like ‘spreaders’ (detergents) or ‘adjuvants’ (enhancers) mixed in to create the chemical cocktail sold simply as ‘glyphosate’.

Few gardeners realise that sometimes these additives can be more hazardous than the active ingredient. In the 1990’s, when I managed the horticultural estate of the Royal Botanic Gardens, Sydney, there was a panic replacement of standard formula glyphosate with a ‘biactive’ formula. Retailers took back the original and swapped it, free of charge.

The ‘biactive’ formula contains a different spreading agent. The reason for this burst of activity was scientific proof that, contrary to advertising, the original formula was lethal to amphibians at all stages of their lifecycle, even for short periods of exposure, and at low doses.

Glyphosate is still used in Australia to spray floating aquatic weeds, like water hyacinth, Eichhornia crassipes. The Queensland Government sprays sources of drinking water, such as the Brisbane River, with glyphosate to control water hyacinth.

The US Environmental Protection Agency considers glyphosate to be relatively low in toxicity 4, and without carcinogenic effects, while the California Environmental Protection Agency’s Pesticides Illness Surveillance programme indicates glyphosate-related incidents are one of the highest reported of all pesticides5.

Independent scientific research provides increasing evidence of toxicity over the past twenty years. Now the world’s most frequently used weedkiller, glyphosate has been linked with spontaneous abortions, non-Hodgkin’s lymphoma, and multiple myeloma in humans.

Glyphosate has been found to kill human placental cells at concentrations below rates approved for agricultural use.

Research has also detected residues in crops of lettuce, carrot and barley planted one year after glyphosate was applied at approved rates. If you eat non-organic bread, it is being made from contaminated flour.

It is important to remember that farming was productive and profitable long before glyphosate was invented. Britain’s Pesticides Action Network has produced ‘Alternatives to glyphosate in weed management’ in anticipation of a ban in the European Union. There are safer alternatives to this chemical.

In Australia there is one regulatory body that assesses and approves all formulas of glyphosate, how they can be used, and their respective rates of application. This is the Australian Pesticides and Veterinary Medicines Authority.

There is a long list of suspect chemicals waiting safety reviews by the APVMA. Glyphosate is one of them. In some instances, reviews have been overdue for decades.

APVMA receives a significant proportion of the funds it needs to function from the licensing of pesticides for sale in Australia.

Grappling with Roundup, by Lynda Brown, published 4.5.2011, W:
2 Roundup (glyphosate) found year round in air, water and rain, by Town & Country Gardening, published 2.9.2011, W:
3 Widely Used Herbicide Commonly Found in Rain and Streams in the Mississippi River Basin, released: 29.8.2011, US Department of the Interior, US Geological Survey Office of Communications and Publishing, 12201 Sunrise Valley Dr, MS 119, Reston, VA 20192. Contact: Paul Capel, Phone: (USA) 612 625 3082, or Kara Capelli, Phone: (USA) 571 420 9408
4, 5 Glyphosate, Wikipedia:

Jerry Coleby-Williams
20th February 2012
Reviewed 11th September 2016


6 Comments Add yours

  1. gretelau2001 says:

    Thanks for the article Jerry. It’s good to be reminded every now and then why we shouldn’t be using this stuff. There’s new information there I haven’t heard before too. Have shared this around.

  2. Jennifer says:

    I don’t use Glyphosate except when it comes to nutgrass, after years of dedicated manual removal failed. Even Glyphosate has not eradicated nutgrass entirely. I have been wondering if application could be via a syringe direct into the base of the plant or paint the leaf to minimise the poison’s contact with the soil? I’m prepared the spend the extra time/effort to mitigate the effects of Gylphosate which I’m loathe to use.

    1. There’s a reason why nutgrass is one of the world’s top twenty worst weeds. Naturally glyphosate doesn’t control nutgrass, it is resistant to this chemical and its growth habit protects it from the chemical’s action. I could have told you that twenty years ago.

  3. Shelly says:

    Jerry, Thought you would be interested in emerging & increasing evidence of how & why GLYPHOSPHATE IS TOXIC TO HUMAN HEALTH (biological mechanisms explained and how this plays significant role in numerous diseases)!!! NOT JUST THREAT TO immediate natural ENVIRONMENT and ecosystem. Look up or see this page for list of research, reviews and presentations by Stephanie Seneff

    See excerpts below from Seneff’s work that can be found in full on web:
    Roundup and GMO and the Rise of Modern
    Disease Stephanie Seneff MIT CSAIL

    Glyphosate contamination in our food supply is a serious threat to
    human health
    •Glyphosate is implicated in autism, breast cancer,Celiac disease, vitamin D deficiency, sleep disorders, osteoarthritis and many other health issues
    •Suspected addition of oxalate to the formulation in 2005 led to significant increases in toxicity to both plants and animals
    •Iron dysbiosis and anemia are important factors
    •Glyphosate may be working synergistically with vaccine ingredients to cause
    increased harm
    Glyphosate may play a significant role in climate change

    Is Roundup the Toxic Chemical that’s Making Us All Sick? June 5, 2014, Groton School, Campbell Performing Arts Center, Groton MA
    We should be very worried about glyphosphate contamination in the food supply

    Glyphosate usage on corn and soy crops correlates with the epidemic we’re seeing in
    autism, Alzheimer’s disease, celiac disease, and
    other intestinal disorders

    This correlation can be explained by the known
    effects of glyphosate in biological systems

    Glyphosate should be banned from agriculture

    Stephanie Seneff is a Senior Research Scientist at the MIT Computer Science and Artificial Intelligence Laboratory. She received the B.S. degree in Biophysics in 1968, the M.S. and E.E. degrees in Electrical Engineering in 1980, and the Ph.D degree in Electrical Engineering and Computer Science in 1985, all from MIT. For over three decades, her research interests have always been at the intersection of biology and computation: developing a computational model for the human auditory system, understanding human language so as to develop algorithms and systems for human computer interactions, as well as applying natural language processing (NLP) techniques to gene predictions. She has published over 170 refereed articles on these subjects, and has been invited to give keynote speeches at several international conferences. She has also supervised numerous Master’s and PhD theses at MIT. In 2012, Dr. Seneff was elected Fellow of the International Speech and Communication Association (ISCA).

    In recent years, Dr. Seneff has focused her research interests back towards biology. She is concentrating mainly on the relationship between nutrition and health. Since 2011, she has written over a dozen papers (7 as first author) in various medical and health-related journals on topics such as modern day diseases (e.g., Alzheimer, autism, cardiovascular diseases), analysis and search of databases of drug side effects using NLP techniques, and the impact of nutritional deficiencies and environmental toxins on human health.

  4. Alana says:

    Hi Jerry, I had started a community garden last year and subsequently moved away because of family. I returned a few months ago to find out that my garden was sprayed with round up to kill grass and weeds in the garden. I planned on it being an organic garden. What do I do now. Is there any way to take out the effects of the chemicals to bring the soil back to health ready for planting? Thanks for any help. Alana

    1. just practise organic gardening: organic matter, be it compost, manure or mulch, plus seaweed, will help activate those microscopic helpers to do what they do best: create healthy, living soil. Glyphosate may hang around for a year, so focus on soil improvement and plant fruit trees first.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.