Exposure to glyphosate, the main ingredient in the weedkiller Roundup, could adversely affect the microbes in our gut, which could lead to poor health. 

Glyphosate is a controversial broad action weedkiller that was introduced onto the market in 1974. Since then, its use has increased worldwide more than 100-fold.

It is controversial, as there have been many claims of toxicity in humans and animals. In 2018, a school groundskeeper in the US won a case against Monsanto – the maker of Roundup – who claimed that extended exposure to the herbicide had caused him to develop non-Hodgkin’s lymphoma. He was awarded $289 million in damages. 

Bayer acquired Monsanto in the same year and then agreed to pay more than $10 billion to settle further lawsuits claiming glyphosate causes cancer. Despite this, the company has no plans to discontinue production of the chemical.

While glyphosate is not considered to be as toxic to bees as neonicotinoid pesticides, research has shown that it can damage bee gut microbes, making them more susceptible to infections.

Now new evidence shows that that 54% of around 101 species of bacteria commonly found in the human gut could be damaged or killed if exposed to glyphosate in high enough quantities.