EXPERT REACTION: First Australian cancer lawsuit over herbicide 'Roundup'
Organisation/s: Curtin University, The University of Western Australia, The University of Sydney
These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.
Associate Professor Nial Wheate is an expert in cancer drugs and pharmaceutics at the University of Sydney
While two related people developing cancer at the same time is clearly worthy of investigation and research, we must be careful not to draw a causal link between their disease and glyphosate. It is important to remember that every year there are many hundreds of thousands of people who use the pesticide, or been exposed to it, who do not develop cancer.
Frankly, I tire of this glyphosate mania, which I hoped would stay in the USA – the silence as scientists wait for people to be sensible seems not to be working, so I will try to say something.
The overwhelming opinion of experts is that glyphosate is safe. People forget ‘the dose maketh the poison’.
The scary data sheets that come with herbicides are for the concentrated compound, plus all the chemicals needed to dissolve it, plus the detergents needed to allow the chemical to penetrate the leaf – the concentrate is a toxic cocktail to be sure.
However, the concentration at which what’s in the bottle is applied is usually 1,000 times less, or even more dilute than that. What might remain behind days or weeks after spraying might be many orders of magnitude more dilute than what it was applied at.
Our exposure to toxins is a constant - some exposure is more noticeable than others. One of our favourite drugs, alcohol, is quite toxic and a KNOWN carcinogen yet we pour it down our throats with vigour every weekend. It is considered a carcinogen by Cancer Australia as well as the IARC who ruled that for ethanol there was “sufficient evidence (highest IARC classification of carcinogenicity)” for it causing cancer of the oral cavity, pharynx, larynx, oesophagus, colorectum, liver (hepatocellular carcinoma), and female breast.
I wish people would trust experts and keep some perspective. If you seriously want to lower your cancer risk, keep using Roundup and stop drinking. I am disappointed to think Australia might go down the same road as the hyper-litigious USA.
The International Agency for Research on Cancer has stated that there is suggestive evidence that glyphosate causes cancer, with the strongest evidence for non-Hodgkin lymphoma. We need more information, particularly in relation to people who use glyphosate intensively for a long period.
Anyone who uses glyphosate should consider whether there are other options for weed control in their circumstances.
If you do use it, then you should download the safety data sheet for that product from the internet or ask for the safety data sheet where you buy your supply. The safety information is in section 8 and is not on the bottle itself.
For glyphosate, the manufacturers recommend wearing eye protection, a respirator with replaceable filter, rubber gloves, and cotton overalls buttoned at the neck and wrist.
A strong message from this is that labelling of pesticides in Australia needs to be improved.
Glyphosate is considered by the International Agency for Research on Cancer to be probably carcinogenic to humans - https://monographs.iarc.fr/wp-content/uploads/2018/06/mono112-10.pdf. Here are the relevant conclusions from the above evaluation:
6.1 Cancer in humans
There is limited evidence in humans for the carcinogenicity of glyphosate. A positive asso- ciation has been observed for non-Hodgkin lymphoma.
6.2 Cancer in experimental animals
There is sufficient evidence in experimental animals for the carcinogenicity of glyphosate.
6.3 overall evaluation
Glyphosate is probably carcinogenic to humans (Group 2A).
In making this overall evaluation, the Working Group noted that the mechanistic and other relevant data support the classification of glyphosate in Group 2A.
In addition to limited evidence for the carcino- genicity of glyphosate in humans and sufficient evidence for the carcinogenicity of glyphosate in experimental animals, there is strong evidence that glyphosate can operate through two key characteristics of known human carcinogens, and that these can be operative in humans. Specifically:
• There is strong evidence that exposure to glyphosate or glyphosate-based formulations is genotoxic based on studies in humans in vitro and studies in experimental animals.One study in several communities in indi- viduals exposed to glyphosate-based formu- lations also found chromosomal damage in blood cells; in this study, markers of chro- mosomal damage (micronucleus formation) were significantly greater after exposure than before exposure in the same individuals.
• There is strong evidence that glypho- sate, glyphosate-based formulations, and aminomethylphosphonic acid can act to induce oxidative stress based on studies in experimental animals, and in studies in humans in vitro. This mechanism has been challenged experimentally by administering antioxidants, which abrogated the effects of glyphosate on oxidative stress. Studies in aquatic species provide additional evidence for glyphosate-induced oxidative stress.'
Note in the above that there is strong experimental evidence that glyphosate can cause cancer. There is also epidemiological evidence that it causes non-Hodgkin lymphoma but this is not conclusive. Here is the relevant summary:
'In summary, case–control studies in the USA, Canada, and Sweden reported increased risks for NHL associated with exposure to glyphosate. The increased risk persisted in the studies that adjusted for exposure to other pesticides. The AHS cohort did not show an excess of NHL. The Working Group noted that there were excesses reported for multiple myeloma in three studies; however, they did not weight this evidence as strongly as that of NHL because of the possibility that chance could not be excluded; none of the risk estimates were statistically significant nor were they adjusted for other pesticide exposures.'
The AHS is the Agricultural Health Study, a large cohort study of workers in agriculture in the USA.
As a probable cause of cancer, the most important thing is for those most likely to be at risk to protect themselves according to best practice in occupational health.
The International Agency for Research on Cancer (IARC) has classified glyphosate as a probable carcinogen. The main cancer type associated with use was non-Hodgkin’s lymphoma.
People should avoid the use of the product if it’s not necessary and those who do need to work with it should take proper health and safety precautions.
When using any pesticide, it is important to download the safety data sheet off the internet for that product or ask for the safety data sheet where you buy your supply. The safety information is in section 8 and is not on the bottle itself.
Safety data sheets advise wearing eye protection, a respirator with replaceable filter, rubber gloves, and cotton overalls buttoned at the neck and wrist.
Cancer Council would like to see safety information listed on the bottle.
As a probable cause of cancer, the most important thing is for those most likely to be at risk to protect themselves according to best practice in occupational health. People should avoid the use of the product if it’s not necessary and those who do need to work with it should take proper health and safety precautions.
The International Agency for Research on Cancer made a bad mistake in claiming glyphosate was a probable cause of cancer. There is no convincing evidence for this and much evidence gathered over 40 years about it as the safest herbicide known. Any replacement will be more likely to be damaging to human health. Of course, I also agree with the previous article from Sydney Institute of Agriculture that it is unfortunate farmers are so reliant on glyphosate and that alternatives as good aren’t available. But just as that SIA article says, finding a replacement as good is very unlikely. The precise specificity for affecting plants only by a chemical inherently so safe to animals is unlikely to be repeated. I sincerely regret that the law is being used so badly in this case.
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