A chemical used in common weedkillers, which may be linked to cancer in humans and the destruction of bee colonies, has been found in a startling proportion of US urine samples, a new report by the Centers for Disease Control and Prevention (CDC) has found. The controversial chemical glyphosate was discovered in 80 percent of adult and child urine samples collected in the experiment, highlighting just how widespread the chemical is.

Glyphosate is a controversial chemical. There are concerns it could have adverse effects on human health, but these are often debated. Previous research has highlighted a link between glyphosate and lymphoma, though a joint meeting between the European Food Safety Authority and the Joint Food and Agriculture Organization (FAO)/World Health Organization (WHO) in 2015 determined it is "unlikely" to be a carcinogen. However, the same year, the International Agency for Research on Cancer declared it “probably carcinogenic to humans”. Bayer, a large pharmaceutical company, has since declared all its products will be glyphosate-free beginning in 2023, though both the EU and US continue to refuse legislation banning it.

The report covered 2,310 urine samples from both adults and children across the US, taking a small sample from each and analyzing for the presence of glyphosate. Out of 2,310 samples, 1,885 were found to contain the chemical. Around one-third of participants were children. This is now the largest study yet to identify the extent of glyphosate in the US population, and it paints a damning picture. 

Used in the popular herbicide Roundup, as well as many industrial herbicides, glyphosate has become subject to intense debate after its discovery by Monsanto scientists in 1970. Around 127 million kilograms (280 million pounds) of glyphosate is used annually by US food growers due to its impressive broad-spectrum performance but also inexpensive cost. It is now one of the most common herbicides in the US, and one of the most widely-used herbicides in history.

The report now calls for better understanding of glyphosate and its potential health impacts, due to its clear nationwide distribution.

Correction: An earlier version of this article described glyphosate as potentially cancer-causing. This has been corrected to reflect the debate surrounding its carcinogenic nature.