Knotweed News

Glyphosate – should we be using it?

Author: Mike Clough

Date Posted: Tuesday 16th January 2018

In recent news – at least if you read publications at the slightly sensationalist end of the spectrum – the “cancer-causing poison” glyphosate has had its licence renewed by the European Union in what is a blow for public health and a victory for amoral multinational corporations led by Lord Business, Crooked Hillary Clinton and Darth Vader. Or something.

Japanese Knotweed Solutions use a variety of pesticides including glyphosate. We have always taken the safety of our employees seriously, but we had never had any reason to doubt that the glyphosate-based products that we use are non-harmful to human health – as is reflected by their classification on official documents, including the products’ safety data sheets.

Since the publication of the monograph on glyphosate by the IARC (the International Association for Research on Cancer – part of the World Health Organisation), JKSL have kept a close eye on the news, and we have actively carried extensive research on the subject, speaking to experts in the field as well as sceptics. This led to and informed an in-depth decision-making process.

JKSL’s decision was to continue to use glyphosate-based products – because we genuinely believe that our use of glyphosate poses no significant risk to human health – including, and importantly that of our employees.

We asked ourselves a few questions:

Is glyphosate safe?

Glyphosate is not 100% safe – but nothing is. Glyphosate is safer than a whole host of things, including many other pesticides. We are confident that using glyphosate-based pesticides is the safest effective approach in the circumstances where we use it. Glyphosate is of very low toxicity compared to many other products.

“Acute toxicity” describes exposure to a large amount of a substance in a short time frame – such as you would see if someone accidentally ingested herbicide.

In terms of acute toxicity, it’s the dose that makes the poison – you can die from drinking too much water, or ingesting too much of anything. Glyphosate is no exception – however, glyphosate is one of the least acutely toxic of all available pesticides. It is less toxic than acetic acid (aka vinegar), which is used in some contact herbicides, and glyphosate is less toxic than salt, aspirin and caffeine.

“Chronic toxicity” refers to continued exposure over a prolonged period – such as you would expect in a spray operator, especially if no protective clothing was used.

In terms of chronic toxicity, glyphosate has the potential to produce chronic health effects in humans – however, again we come to the question of dosage. It is likely that any exposure to glyphosate through diet is as little as 0.1% of the European Food Safety Authority [EFSA]’s reference dose – the estimated daily exposure that is likely to result in no adverse effects over a person’s lifetime. Exposure for operatives is higher, but only by a couple of times – meaning that even operatives who are regularly spraying glyphosate-based products are likely to receive significantly less than 1% of the amount that would be needed to potentially cause long-term health issues.

Does glyphosate cause cancer?

Basically, no. Glyphosate has not been shown to cause cancer in the real world. In terms of cancer-causing potential (carcinogenicity), glyphosate is not considered a carcinogen by EFSA. What’s more, glyphosate is not even classified as a confirmed carcinogen by the IARC – whose report has been used so widely in headlines and in calls for a ban.

The IARC classifies glyphosate as Group 2a: “probably carcinogenic to humans”, but even this is based on theoretical potential to cause cancer – not the possibility of cancer being caused by real-world exposure. EFSA doesn’t even consider cancer as one of the potential chronic effects that glyphosate could cause, and as we have seen above, real world exposures to glyphosate fall far below the threshold for chronic effects. The possibility of cancer being caused by real-world glyphosate exposure (even glyphosate poisoning) is simply not backed up by any science.

Continuing to explore the IARC classification of glyphosate, the IARC provides a list of Group 1 confirmed carcinogens (the category above glyphosate), which includes:

  • Outdoor air pollution and diesel engine exhaust
  • Alcoholic beverages
  • UV tanning beds
  • Certain menopausal therapy pharmaceuticals (HRT) and types of birth control pills
  • Indoor coal fires
  • Tobacco smoking (including second-hand smoke).
  • Working as a painter, chimney sweep, welder or in iron and steel foundry
  • Wood dust, leather dust, silica dust
  • Chinese-style salted fish
  • Areca nuts

While some of these are controlled to some degree or other, again, we don’t see MEPs calling for bans on tobacco sales, alcohol or tanning salons, and people are not up in arms protesting the evils of Dulux paint, coal fires or electric sanders. And remember, the list above are all confirmed carcinogens, according to the IARC.

Calls to ban glyphosate on the grounds of protecting public health are misguided and directed at the wrong target. There are potential achievable improvements, particularly in air quality that would have real effects on reducing cancer – but to ban glyphosate on health grounds would not be disproportionate – it would be completely ineffective in achieving its stated goal.

Who do JKSL expose to glyphosate, and how much?

Japanese Knotweed Solutions use glyphosate in relatively small amounts (especially compared to agriculture, but even in comparison to many other amenity contractors). The exposure to our workforce is limited, and the exposure to our clients, their children and pets or their workers should be zero for all practical purposes, so long as the application is done using JKSL’s safe system of work.

Studies have shown that in normal use, exposure to glyphosate for operators falls way below the exposure levels for both acute and chronic toxicity, so we are confident that it’s safe for our staff too.

What about glyphosate in food?

First of all, JKSL don’t normally apply herbicide on or around crops or in other agricultural settings – our work is limited to work in homes, amenity sites and development sites. Where we have carried out herbicide application on grazing land, or adjacent to cropland, this is done at a suitable time of year, and with full consultation of all relevant stakeholders.

Unfortunately, for gardens or allotments that we are treating, we do have to state to our clients that no produce from the garden should be eaten while the treatment program is in progress. However, this is more for technical reasons than because we believe that there is any danger.

The main factors are that we use higher dose rates (as recommended on the product label) for treating Japanese knotweed than you would use in agricultural settings, the applications may exceed the rates allowed for use on crops, and also because the timing of our applications – which generally includes an application late in the growing season – may be later than is allowed by the product label for use on crops. These dose and application rates and application cut-off dates are legal requirements for the use of professional pesticides, so we must follow them.

Ideally, of course, glyphosate wouldn’t be found in any produce at all, but where it is used, there will often be some very small amounts of the herbicide found in the produce. In the UK, we use a system of MRL’s (Maximum Residue Levels) to indicate what the acceptable levels of pesticides are in a variety of different crops.

The MRL is a best-practice guideline, to indicate that pesticides are being used appropriately; MRL’s are not “safe limits” – in fact the safe levels are likely to be many, many times higher for most pesticides. Many of the MRLs are limited by the ability of tests to even detect amounts so small (the limit of detection is currently 0.1mg/kg in the UK, and this is a common MRL for glyphosate in crops).

As a comparison, it’s legitimate under US Food and Drug Administration (FDA) regulations for your peanut butter to contain up to 30 pieces of insect per 100g before it is classed as contaminated, whereas the UK MRL for Glyphosate in peanuts is 0.1mg/kg – less than one part per million.

If you want a more numerical comparison, the MRL for glyphosate in cocao is 0.1mg/kg but the FDA allows up to 100mg/kg of rodent faeces in raw cocoa – that’s 1,000 (yes, one thousand) times as much rat poop allowed in your chocolate as glyphosate.

So, what did JKSL conclude?

When you get down to it, we are confident of all of the following facts:

  • Our herbicide applications will not cause contamination in food products
  • Our herbicide applications, carried out using the safety measures we put in place do not pose a significant risk to our operatives, our clients or members of the public
  • We are not putting people at any additional risk of cancer
  • The work that we do is important, and relies on the use of herbicide to safely manage Japanese knotweed and other problem plants in a variety of situations.

But if that ever changes, if new information about health or environmental protection shows us that there are additional risks, or if we are no longer confident that we are doing the right thing, we will stop. Simple as that.

Chris Oliver
Operations Manager

Further reading

IARC list of carcinogens

HSE information on MRLs

Is glyphosate carcinogenic?

On the acute and chronic toxicity of glyphosate

ECHA finds glyphosate is safe for public use

EFSA removes barriers to glyphosate renewal

EU re-licences glyphosate for five years


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Mike Clough

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