Glyphosate: What's wrong with the pesticide?

The US chemical company Monsanto used glyphosate, a mixture of the organic phosphorus compound with other substances, to create the weedkiller Roundup, which it first distributed in 1974.

Farmers worldwide continue to spray their fields with the herbicide to kill off green weeds before a crop is sown. The chemical spray also inhibits the growth of weeds that can outcompete crops while they are growing. 

Pesticides containing glyphosate are now manufactured by several dozen chemical companies worldwide. Germany's Bayer AG acquired Monsanto, including its top-selling product Roundup, in 2018 and maintains "a leading position" in the herbicides market, Bayer press spokesman Utz Klages told DW. 

What's the problem with glyphosate?

Killing wild weeds and plants on agricultural fields deprives insects of their habitat. This, in turn, deprives birds of food.

"The herbicide destroys the nutritional basis for animals," Jörn Wogram, head of the pesticide department at Germany's Federal Environment Agency, told DW. "Thus glyphosate, along with other pesticides, threatens biodiversity."

According to studies, glyphosate-based sprays might also alter genetic material and affect the nervous system in animals and humans. For example, a study by the University of Ulm found massive malformations in tadpoles, with disorders of the brain, heart, eyes and body shape due to exposure to the herbicide. 

Since the toxin is spread through the air when sprayed on fields, it contaminates widely, from surface water and groundwater to agricultural produce. Traces have been found in human urine and breast milk.

Pesticides containing glyphosate are sprayed in large quantities in soy production, such as the genetically modified soy seeds created by Monsanto to be resistant to Roundup. Health consequences include a higher risk of cancer within farming communities.

"We can see very clearly that people are getting sicker from glyphosate," said Medardo Avila Vazquez, a physician at the University Hospital of Maternity and Neonatology in Cordoba, Argentina and the co-author of studies on the health impacts of glyphosate on agricultural populations. "In certain rural areas, they are three times more likely to have cancer."

The use of glyphosate in soybean-growing areas increased the number of miscarriages by a factor of between two and three, Avila Vazquez told DW. Meanwhile, damage to genetic material "quadrupled the number of malformations," he added.

Cancer researcher Luoping Zhang of the University of Berkeley in California has evaluated the link between glyphosate and types of lymphoma, including non-Hodgkin lymphoma.

"People exposed to glyphosate or glyphosate-based herbicides have a 41% higher risk of developing non-Hodgkin lymphoma," Zhang told DW of one study. 

Other independent studies show that glyphosate can damage the nervous system, leading to Parkinson's disease. The herbicide also harms microorganisms, changing the vital composition of gut bacteria essential for human health.

How are the cancer research agency and regulatory authorities responding? 

In 2015, the International Agency for Research on Cancer concluded, based on independent and published studies, that glyphosate is probably carcinogenic.

However, the national authorities responsible for approving glyphosate rely almost exclusively on research provided by pesticide manufacturers. These studies are not public, have not been independently verified and have been criticized by scientists.

By contrast, the European Food Safety Authority (EFSA) released an assessment in July 2023 stating it could not identify "critical areas of concern" concerning the impact of glyphosate on the health of humans, animals and the environment. While acknowledging that it could not make a comprehensive evaluation due to "data gaps," it did recommend that glyphosate be considered for EU reauthorization.

"Pesticide producers withheld studies on neurotoxicity in the EU authorization procedure," stated toxicologist Peter Clausing of the Pesticide Action Network regarding the EFSA assessment. The process is marked by "unacceptable secrecy," he added. 

Clausing said toxicologists, health experts, environmentalists and some farmers would see a ban as a win for the environment and human health.  

He believes the herbicide should be phased out and the agricultural sector should be broadly reformed. 

For example, farmers should be better supported to adopt sustainable farming techniques.

"Organic farming shows that farming without herbicides, such as glyphosate, is quite possible and has developed numerous innovations on how to farm well without them," said Saskia Horenburg of the German Federation of the Organic Food Industry.

Measures include the introduction of new cereal varieties that produce shade with their leaves and thus "suppress" weed growth, Horenburg explained.

What would the reauthorization of glyphosate mean?

The European Commissionextended glyphosate approval for 10 years on November 16 with some restrictions, such as cap on the amount that can be sprayed. 

The continued use of glyphosate and other herbicides "jeopardizes the achievement of sustainability goals related to environmental protection," said Wogram of the German Federal Environment Agency in September.

For the countries of the Global South, the EU decision "undoubtedly has enormous significance," said Larissa Mies Bombardi, who researches the consequences of pesticides in Brazil.

If Europe chooses to ban glyphosate spraying, she believes this would have a significant signal effect on Brazil and other countries.

Pesticides can be more easily sold when EU authorities claim that environmental and health problems are not a major concern. This would change with a ban.

This article was originally written in German and was updated on November 16, 2023 following the European Commission's approval to extend the use of glyphosate.