The Link Between Glyphosate – Roundup and Cancer
In 2015, researchers at the World Health Organization declared that glyphosate was a probable carcinogen. This announcement by the IARC – the International Agency for Research was met by a backlash from industry insiders. Since then, the waters have become even more muddied with the state of California recently classifying the chemical as a cancer risk. So what is glyphosate and what do we know about its health concerns?
What is Glyphosate?
Glyphosate is a chemical herbicide used around the globe to kill weeds. It was made commercially available in 1974 in a formula marketed by Monsanto under the name – Roundup. It is the main active ingredient in over 750 commercial herbicides with glyphosphate formulations being the biggest selling pesticides around the world today.
Glyphosate is combined in commercial formulas with several other chemicals to improve its efficiency in killing weeds and to enhance the plant’s ability to take the herbicide on board. The use of glyphosate around the world has risen exponentially since glyphosphate resistant GM crops were introduced in the mid 1990s. Glyphosate formulations are widely used in forestry, agriculture and domestic gardening.
Glyphosate is a type of non-selective herbicide which basically means that it can kill the vast majority of plants. It was discovered in 1970 by a chemist for Monsanto called John Franz and by now is not under patent. Monsanto and several other companies have developed seeds that are able to tolerate the chemical which allows farmers to use it on whole fields without it destroying their crops.
Glyphosate is Everywhere
If glyphosate is indeed a carcinogen, there is reason to be alarmed. It is widespread in today’s environment and detectable in the soil, air and water while it has also been detected in humans.
Studies in the US and Europe have routinely identified glyphosphate residue in human urine resulting from dietary intake or occupational use. (1)
One recent German study that monitored over 2000 people found evidence of glyphosate residue in 99.6% of them. And one third of those people had a level between 10 and 40 times greater than the safe exposure threshold. (2)
In the UK for example where the Food Standards Agency conducts annual residue testing,they have found glyphosate to be extremely common. The agency has found that bread is frequently contaminated with glyphosate residue being identified in up to 30% of all grain based samples taken from the year 2007 to 2013 with the levels rising each year.
What is the Evidence Linking Glyphosate to Cancer?
The safety of glyphosate has been put under regulatory and scientific scrutiny since way back in the 1980s. The Environmental Protection Agency of the European Union and many other international regulatory bodies around the world have reviewed it on a regular basis. These regulatory bodies including agencies in Europe, New Zealand, Japan and Canada have said that it is not like to cause human cancers.
The review by the IARC noted that the evidence for a link between glyphosate and cancer in humans was limited. However, there have been several studies showing that people who work with it are at an increased risk of non-Hodgkin lymphoma – a type of cancer.
The IARC report however notes that a very large US study could find no link between non-Hodgkin lymphoma and glyphosate. This huge study monitored thousands of farm workers to establish whether or not their risk of developing cancer increased. (3)
There is also some strong evidence that glyphosate mimics the actions of estrogen in high concentrations. (4) There are concerns that this could increase the risk of breast cancer in women exposed to very high levels of the chemical but there is no elevated risk linked to more everyday exposure.
Commercial glyphosate formulations when used in combination with various other chemicals are exponentially more toxic than glyphosate when it is used alone. Some estimates put the figure at up to a thousand times the level of toxicity. (5)
Certain additives to these commercial formulas such as surfactants used to help glyphosate enter into the plants are actually toxic in and of themselves. They are also known to significantly increase the toxicity of glyphosate when combined.
Animal studies have found that certain contaminants found in glyphosate formulations like 1,4-dioxane have caused various types of cancer including breast, nasal and liver cancer. (6)
The IARC used this body of evidence to classify glyphosate as ‘probably carcinogenic’. It also used less direct evidence called ‘mechanistic evidence’ including DNA damage in human cells resulting from glyphosate exposure.
Whether or not glyphosate is a carcinogen is a very controversial topic and there are no signs of the controversy abating. Several reviews have concluded that it is not carcinogenic (7) but the IARC classification looms large over the industry.
As we have already mentioned, the IARC based its classification on three studies which they regarded as reliable and showed a positive link between the chemical and Non-Hodgkin lymphoma. They also concluded glyphosate was genotoxic and took animal studies into consideration.
Just a few months back in June of 2017, California state added to the controversy by classifying glyphosate as a chemical which was ‘known to cause cancer’. (8)
California’s Office of Environmental Health Hazard Assessment added glyphosate to its list of chemical which can cause cancer. This list is kept by California state because of Proposition 65 – a law requiting businesses to give warnings to the residents of the sate regarding significant exposure to chemicals which can cause cancer, birth defects and reproductive harm.
Monsanto continues to insist that glyphosate does not pose a cancer risk. They claim that the listing of the chemical under Proposition 65 is not warranted based on the law or on science. They have sued the Californian regulatory body to put a stop to the listing.
They claim that the original classification by the IARC back in 2015 was based on flawed scientific evidence. According to Monsanto, the studies on which the classification was based ignored critically important data and therefore undermines their conclusion.
According to Monsanto, over 800 separate studies from around the globe have demonstrated that glyphosate is safe. It is true that since the chemical was classified as a carcinogen in 2015, regulatory bodies including agencies in Australia, Europe and Japan have affirmed that it is not carcinogenic.
Nevertheless more than 800 people suffering from non-Hodgkin’s lymphoma claim Roundup caused their cancer and are in the process of suing Monsanto.
What the Future Holds
Despite the ruling by the State of California, there is lingering uncertainty whether or not Monsanto will ultimately be forced to issue warning on glyphosate-based products sold within the state.
The actual wording of the law is as follows…
“a warning must be given for listed chemicals unless the exposure is low enough to pose no significant risk of cancer or is significantly below levels observed to cause birth defects or other reproductive harm.”
So, the big question that remains unanswered is whether the amount of exposure to glyphosate from using Roundup was sufficient to constitute the significant risk as required by the law.
It also remains unclear just how much exposure would constitute a real and significant risk. These questions are unlikely to be answered until more data becomes available some time in 2018.