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Is glyphosate safe? A close look at Roundup’s key ingredient

Is glyphosate safe? The active ingredient of the world’s most widely used herbicide, Roundup, is arguably also one of the most contentious. After decades of believing it posed a risk only to plants, there are growing concerns over its effect on people. But the debate is far from settled.

Credit: Wikipedia Commons

While many studies claim that glyphosate is safe and environmentally friendly, others have linked it to serious health issues like cancer and called for a worldwide ban. We took a detailed look at the issue and provided answers to some of the key questions behind it.

What’s glyphosate?

Glyphosate is the active ingredient in many weedkillers. It was introduced by Monsanto in 1974, its patent expired in 2000 and now it is sold by various manufacturers.

It is one of the most widely used herbicides in the United States. People apply it in agriculture and forestry, on lawns and gardens, and for weeds in industrial areas. Some products containing glyphosate control aquatic plants.

Farmers spray it on fields before their crops emerge in spring, so the crops do not have to compete with weeds. Some also use it as a pre-harvest treatment to dry out crops and make them easier to harvest. The UK Soil Association says such use is risky, as it can increase glyphosate residues in food.

How widely is it used?

The use of glyphosate skyrocketed after seeds were genetically engineered to tolerate the chemical. Because these seeds produce plants that are not killed by glyphosate, farmers can apply the weed killer to entire fields without worrying about destroying crops.

In the US, more than 750 products contain it. In 2017 the European Union extended the license for use of glyphosate for five years, with a strong debate among EU countries. Sri Lanka banned the use of glyphosate in 2015 – though the tea industry opposes the ban. Colombia stopped aerial spraying of glyphosate in 2015 but then reintroduced it.

What happens to glyphosate in the environment?

Glyphosate binds tightly to soil. It can persist in soil for up to 6 months depending on the climate and the type of soil it is in. Glyphosate is broken down by bacteria in the soil. It is not likely to get into groundwater because it binds tightly to soil. In one study, half the glyphosate in dead leaves broke down in 8 or 9 days. Another study found that some glyphosate was taken up by carrots and lettuce after the soil was treated with it.

How extensive is human exposure to glyphosate?

Because of its widespread use, glyphosate is in water, food, and dust, so it’s likely almost everyone has been exposed. And human exposure, through food and water, will probably increase in tandem with the growing use of the weed killer, according to a 2016 study published in the journal Environmental Sciences Europe.

But little is known about the magnitude of human exposure because food and water are not regularly tested for glyphosate residue. However, a few years ago, researchers tested the urine of a small group of people across the United States and found glyphosate residue in 93% of them.

Which foods contain glyphosate?

The main foods that contain glyphosate are genetically modified (GM), glyphosate-resistant crops, such as corn, soybeans, canola, alfalfa and sugar beets.

One recent study found that all 10 genetically modified soy samples examined contained high levels of glyphosate residues. On the other hand, samples from conventional and organically grown soybeans did not contain any residues.

What’s more, many weed species are now resistant to glyphosate, which is causing more and more Roundup to be sprayed on crops.

What are some symptoms from a brief exposure to glyphosate?

Pure glyphosate is low in toxicity, but products usually contain other ingredients that help the glyphosate get into the plants. The other ingredients in the product can make the product more toxic. Products containing glyphosate may cause eye or skin irritation.

People who breathed in spray mist from products containing glyphosate felt irritation in their nose and throat. Swallowing products with glyphosate can cause increased saliva, burns in the mouth and throat, nausea, vomiting, and diarrhea. Fatalities have been reported in cases of intentional ingestion.

Pets may be at risk if they touch or eat plants that are still wet with spray from products containing glyphosate. Animals exposed to products with glyphosate may drool, vomit, have diarrhea, lose their appetite, or seem sleepy.

Is glyphosate likely to contribute to the development of cancer?

Animal and human studies were evaluated by regulatory agencies in the USA, Canada, Japan, Australia, and the European Union, as well as the Joint Meeting on Pesticide Residues of the United Nations and World Health Organization (WHO).

These agencies looked at cancer rates in humans and studies where laboratory animals were fed high doses of glyphosate. Based on these studies, they determined that glyphosate is not likely to be carcinogenic. However, a committee of scientists working for the International Agency for Research on Cancer of the WHO evaluated fewer studies and reported that glyphosate is probably carcinogenic.

Can it be worse for those heavily exposed to glyphosate?

Evidence is mounting that people who are heavily exposed to it — farmworkers and landscapers, for example — have an increased risk of non-Hodgkin lymphoma.

A review led by University of Washington scientists published found that agricultural workers who used a lot of glyphosate had a 41% higher risk of contracting non-Hodgkin lymphoma over their lifetimes than people who used it infrequently or not at all.

On average, about 2 out of every 100 Americans develop non-Hodgkin lymphoma. For people who are highly exposed to glyphosate, the disease rate jumps to 2.8 per 100. That means they still have a relatively small chance of contracting the disease, but their risk is substantially higher because of glyphosate use.

Are there other negative effects?

There are hundreds of different types of microorganisms in your gut, most of which are bacteria. Some of them are friendly bacteria and are incredibly important for your health.

Roundup may negatively affect these bacteria. It blocks the shikimate pathway, which is important for both plants and microorganisms
In animal studies, glyphosate has also been found to disrupt beneficial gut bacteria. What’s more, harmful bacteria seemed to be highly resistant to glyphosate.

One article that received a lot of attention on the internet even hypothesized that the glyphosate in Roundup is to blame for the increase in gluten sensitivity and celiac disease worldwide. However, this needs to study a lot more before any conclusions can be reached.

If I use glyphosate products, what precautions should I take?

Carefully follow label instructions and warnings. Wear gloves and don’t let the chemical come in contact with your skin, clothing or eyes. Use it only on calm, rain-free days to prevent drift. Do not let it run off into waterways or gutters. Pets and people should wait until treated areas are dry before entering them

Germany to ban glyphosate use by 2023

The Cabinet of Germany — the federal republic’s chief executive body — announced on Wednesday that it will ban the use of glyphosate from the end of 2023. Glyphosate, also known as the brand name Roundup, has been linked to various types of cancer and is the subject of thousands of lawsuits.

Credit: Flickr, Loco Steve.

The decision is part of a conservation program initiated by the nation’s environment minister Svenja Schulze. Once it enters into force, the bill will prohibit the use of glyphosate in domestic gardens and on the edge of farmers’ fields. The use of the herbicide will also be prohibited around grasslands, orchard meadows, and along some river and lake shores rich in wildlife.

In July, Austria completely banned the chemical for all uses, becoming the first EU country to do so, while in France, 20 municipalities have banned it last month. Restrictions are also being enforced in the Czech Republic, Italy, and the Netherlands.

Glyphosate is the most frequently used herbicide both worldwide and in the EU and it has been used for several decades. The chemical is used primarily to combat weeds that compete with cultivated crops or present problems for other reasons (e.g. on railway tracks).

The herbicide, developed by Bayer-owned Monsanto, is the subject of a heated debate after the World Health Organization (WHO) issued a report concluding that it probably can cause cancer. Bayer, which bought Monsanto in 2018 for nearly $63 billion, says that most studies and regulators have deemed glyphosate safe.

The nearly 18,000 people who have sued Bayer over concerns that glyphosate is responsible for causing their cancer are of a different opinion. In August of last year, a California jury found that Monsanto should have warned of the alleged cancer risks and ordered the company to compensate each plaintiff with tens of millions of dollars. Bayer hopes that research concluding glyphosate is not cancerogenic will sway U.S. appeals courts to reverse or tone down the first three court rulings.

Biologists also say that the chemical may be involved in the dramatic decline of insect populations, which is threatening to disrupt the food chain and plant pollination.

In 2017, the EU Parliament voted to ban the use of glyphosate by 2022. However, the executive branch of the European Union, the Commission, later voted to extend the license of the herbicide for another five years.

This decision has proven extremely controversial among the block’s countries. Austria, Belgium, Croatia, Franca, Cyprus, Greece, Italy, Luxembourg, and Malta voted against the extension.


Glyphosate might be killing bees by messing with their gut bacteria


Credit: Pixabay.

Glyphosate, a broad-spectrum herbicide, has been in wide use since the 1970s with farmers looking to control weeds. Its manufacturer, Monsanto, has always claimed that the chemical only affects plants, being harmless to animals. A new study, however, shows that Glyphosate may be indirectly killing bees by disrupting the microbial community living in their digestive system. As such, the most popular herbicide in the world may be another important factor contributing to the alarming decline in bee populations all over the globe.

“We need better guidelines for glyphosate use, especially regarding bee exposure, because right now the guidelines assume bees are not harmed by the herbicide,” said Erick Motta, a graduate student at the University of Texas Austin, who led the research. “Our study shows that’s not true.”

Glyphosate is a non-selective herbicide, meaning it will kill most plants — including crops and weeds. It works by blocking a specific enzyme, the shikimic acid pathway, which prevents the plant from making key proteins required for growth. The shikimic acid pathway is not found in animals, which is why glyphosate is deemed non-toxic to humans.

However, the enzyme is used by some bacteria. Researchers at the University of Texas in Austin wondered whether glyphosate might be affecting bacteria strains living in the intestines of honey bees (Apis mellifera). They collected 2,000 bees from a hive and fed them sugar syrup dosed with herbicide levels they might encounter in real life.

Three days after they returned to their hives, the glyphosate-exposed bees had fewer Snodgrassella alvi bacteria in their guts than those which were not exposed. Confusingly, the bees that got the highest dose of glyphosate had a microbiome closer to optimal levels compared to bees that received the lowest dose of the herbicide. The researchers say that this may be due to the fact that bees with the highest dose died, leaving behind the resistant variety.

Things become clearer in later tests that showed that glyphosate-laden bees had five times less of the S. alvi bacterium. And when the researchers cultured the bacteria in a petri dish, its growth was very slow or stopped altogether when exposed to a high dose of glyphosate.

Writing in the Proceedings of the National Academy of Sciences, the authors suspect that changes in the bee’s microbiome make the bees more vulnerable to infections. Only 12% of the bees fed with glyphosate survived an infection from Serratia marcescens compared with 47% that were not fed glyphosate. S. marcescens is a bacteria that is widely found in beehives and bee guts that can invade other parts of a bee’s body, leading to lethal infections.

“Studies in humans, bees and other animals have shown that the gut microbiome is a stable community that resists infection by opportunistic invaders,” Moran said. “So if you disrupt the normal, stable community, you are more susceptible to this invasion of pathogens.”

S. alvi lines part of the gut wall and, as such, could act as an insulating layer against the potentially lethal S. marcescens. Additionally, S. alvi also secrets a chemical that can disrupt the invading bacterium.

The findings offer an alternative explanation for the massive decline in bee populations seen all over the world. For instance, beekeepers in the U.S. lost 42.1 percent of their bee colonies in just one year, between April 2014 and April 2015.

“Since the 1980s, honeybees and beekeepers have had to deal with a host of new pathogens from deformed wing virus to nosema fungi, new parasites such as Varroa mites, pests like small hive beetles, nutrition problems from lack of diversity or availability in pollen and nectar sources, and possible sublethal effects of pesticides, ” the USDA notes. But deaths began to spike in the middle of the past decade, when a phenomenon in which bees deserted their hives and died en masse – later named colony collapse disorder – began sweeping hives worldwide. “Commercial keepers were particularly prone to summer losses.”

Previously, scientists have linked colony collapse disorder (CCD) with pesticides, habitat loss, climate change, parasites, stress, and lack of flowers. In this constellation of stressors threatening the most important pollinators on the planet, glyphosate may also pose an important risk.

“It’s not the only thing causing all these bee deaths, but it is definitely something people should worry about because glyphosate is used everywhere,” said Motta.

The findings also raise some important questions about glyphosate’s safety. Perhaps it is affecting the microbiome of other animals, including humans. Previously, the science has been conflicting in its assessment of whether the chemical is carcinogenic or not.