Hope and spray: Does weedkiller widely used in SA cause cancer?
Despite a landmark US ruling, local experts opinion is still sharply split over Monsanto’s Roundup
* This story has been updated
A US jury has found that the main ingredient in one of SA’s most widely used weedkillers causes cancer, but local and international experts disagree about its health risk.
Glyphosate, the main ingredient in Roundup, was found to have been the cause of US school groundsman Dewayne “Lee” Johnson’s NonHodgkin lymphoma, a rare type of blood cancer.
The jury awarded the terminally ill man $289m (R4,2bn) last week.
But figuratively speaking, the jury is still out on whether it really causes cancer, depending on who you speak to.
Most local experts approached by Times Select believed Roundup was not harmful, while Monsanto, the company that created the herbicide, said there were more than 800 studies showing it is safe.In SA’s dry climate farmers need such a herbicide, and taking it off the market could cost farmers worldwide billions in lost income, said one expert.
Monsanto said: “Glyphosate does not cause cancer. The jury got it wrong. We will appeal the jury’s opinion and continue to vigorously defend glyphosate, which is an essential tool for farmers and others. We are confident science will prevail upon appeal.”
The herbicide kills weeds, leaving more space and water for plants to grow, thereby increasing crop yields. A lot of genetically modified maize, corn and soya is designed not to be killed by the weedkiller.
More than 84% of maize in SA is genetically modified and at least 50% is designed to be resistant to glyphosate, according to The African Centre for Biodiversity.
The US Environmental Protection agency, the European Food Safety Authority, New Zealand authorities and a court in California have found the weedkiller to be safe. In 2017, it was relicensed for use in Europe, including in Germany, which had stopped using it.Last week, a California judge ruled that the state could not force manufacturers to place a cancer warning on the weedkiller because the “heavy weight of evidence” showed glyphosate was safe.
Cape Town doctor Harris Steinman, whose company specialises in food safety, said: “Essentially the argument is that many studies have found glyphosate to not cause cancer (according to scientists, and Monsanto), so how could a jury find in favour of the person suing Monsanto?"
The head of department in soil, crop and climate sciences at the University of the Free State, Professor Linus Franke, said glyphosate receives so much attention because it was invented by Monsanto, which is the “company everybody loves to hate”.Monsanto is unpopular due to its genetically modified crops and patents on the seeds it manufactures. Franke said: “People are always suspicious of Monsanto.”
The “vast majority of studies suggest glyphosate is safe to use” said Franke. “It is one of most benign herbicides and breaks down within weeks,” he said.
Johannesburg-based Monsanto scientist Andrew Bennett said that within two days after use, glyphosate cannot be found in soil because it gets broken down quickly.
Bennett said the herbicide’s effectiveness in getting rid of weeds increased crop yields, especially in a dry country such as SA. “You can’t have weeds competing for water”.
Glyphosate is good to reduce global warming, he added.
Farmers using it don’t have to plough land to remove weeds. Turning the soil releases carbon dioxide, said Bennett.
“Worldwide use of glyphosate, which stops tilling of soil, is the equivalent of taking off 16 and half million cars from the road.
“If glyphosate were banned globally, the loss of farmer income would be $7bn a year because they would not kill as many weeds and would not have such a high crop yield.
“The jury is sympathetic towards someone who has cancer. We are all sympathetic”
Bennett said that before a product is allowed to be sold it has to be registered, and has to undergo many scientific checks by a regulator.The regulators look at toxicity and the effects on the environment. “Four times less coffee is needed to kill a rat than glyphosate,” he said.
“Coffee is more toxic than glyphosate.”
But Mariam Mayet, of the African Centre for Diversity, called on SA to play it safe and ban the product.
“Until more information is gathered we would recommend a moratorium on the use of glyphosate in South Africa. A recently published *Seralini study, on the severe health impacts on rats given water containing traces of glyphosate, is a damning indictment of the pesticide industry’s assurances that glyphosate is safe. Until we have more independent scientific evidence on the safety of glyphosate in SA, we should err on the side of caution.”
Paul Pharoah, a Cambridge University professor of cancer epidemiology (the study of the the causes of cancer), told Times Select: “My view is that there is no reasonable evidence to suggest an increase in cancer risk in humans.
“It is not possible in science to ‘prove’ a negative, for example, that glyphosates are not associated with cancer. However, the evidence from studies of farmers that there is an association is extremely weak.”Alcohol ‘more risky’
The International Agency for Research on Cancer (IARC), which is part of the World Health Organisation, listed glyphosate as a “probable cause of cancer” with “limited evidence in humans”. At least one study done in the 1980s by Monsanto found it could cause cancer in rats.
The IARC list of what probably causes cancer includes red meat, extremely hot drinks and shift work that disrupts sleeping patterns. Alcohol is categorised as more risky than glyphosate by the IARC.
Franke said: “You need to see it in perspective. Glyphosate is the mostly widely studied herbicide in the world, due to its links to Monsanto. If you study something enough, you will link it to anything. Other herbicides are not necessarily safer, they just haven’t been studied as much.
“[This is] one of the problems with a judicial system with jurors. It is a group of ordinary people, and with all the information and smoke and mirrors produced, it is hard for ordinary people to judge how toxic glycophosphate is in reality.”
* This story has been updated
The Seralini study quoted by Mariam Mayet that found rats fed glyshophate had a higher incidence of tumours was retracted by the publisher.
Elsevier retracted the study because of concerns that the breed of rats used has a high-incidence of naturally occurring tumours. The numbers of rats studied were so few, the results were not statistically significant. There were also concerns about animal cruelty.
In 2013, Elsevier announced: “A more in-depth look at the raw data revealed that no definitive conclusions can be reached with this small sample size regarding the role of ... glyphosate in regards to overall mortality or tumour incidence. Given the known high incidence of tumours in the Sprague-Dawley rat, normal variability cannot be excluded as the cause of the higher mortality ... observed in the treated groups.‚