NIH Archives

March 1, 2023

California researchers link popular weedkiller to health problems in young adults

By Carey Gillam

Children exposed to a weedkiller commonly used in farming, as well as on residential yards and school playgrounds, appear to be at increased risk for liver inflammation and metabolic disorders in young adulthood and more serious diseases later in life, according to a study published Wednesday in the journal Environmental Health Perspectives.

The research, which was conducted by several California scientists and health researchers, including from the University of California, Berkeley School of Public Health, is the latest of many studies linking glyphosate herbicide to human health problems.

Glyphosate is better known as the active ingredient in Monsanto’s Roundup products as well as scores of other weedkilling brands sold around the world. The chemical is considered the most widely used herbicide in history, and residues are commonly present in food and water, as well as in human urine.

Monsanto and Bayer AG, which bought Monsanto in 2018, maintain that Roundup and other glyphosate-based herbicides are safe when used as directed, and say the weight of scientific evidence demonstrates that safety. But more than 100,000 people in the US have alleged exposure to the weedkiller caused them to develop non-Hodgkin lymphoma. Many independent scientific studies have linked glyphosate to cancers as well as liver disease, endocrine disruption and other health problems.

In the new study, researchers tracked 480 “mother-and-child duos” who live in the Salinas Valley of California, a key agricultural area, analyzing levels of glyphosate weed killer used in the area and levels of the weedkiller present in the urine of the mothers while they were pregnant and in the children as they grew. They also took into account levels of a degradation product of glyphosate known as AMPA in the urine of the study subjects. The researchers then assessed the liver and metabolic health of the children at the age of 18.

They concluded that higher levels of glyphosate residue and AMPA in urine in childhood and adolescence were associated with higher risk of liver inflammation and metabolic disorders in young adulthood. In addition, they found that agricultural use of glyphosate near participants’ homes from birth and up through age five was associated with metabolic disorders at age 18. Metabolic disorders in youth can lead to heart disease, stroke, type 2 diabetes, and liver disease later in life.

Both metabolic problems and liver disorders are increasing among children and young adults, according to the study.

January 19, 2023

New US research finds “worrying” evidence linking Monsanto weedkiller to cancer

By Carey Gillam

New research by top US government scientists has found that people exposed to the widely used weed killing chemical glyphosate have biomarkers in their urine linked to the development of cancer and other diseases.

The study, published last week in the Journal of the National Cancer Institute, measured glyphosate levels in the urine of farmers and other study participants and determined that the presence of the pesticide was associated with signs of a reaction in the body called oxidative stress, a condition that causes damage to DNA. Oxidative stress is considered by health experts as a key characteristic of carcinogens.

The authors of the paper – 10 scientists with the National Institutes of Health and two from the Centers for Disease Control and Prevention (CDC) – concluded that their study “contributes to the weight of evidence supporting an association between glyphosate exposure and oxidative stress in humans.” They also noted that “accumulating evidence supports the role of oxidative stress in the pathogenesis of hematologic cancers,” such as lymphoma, myeloma and leukemia.

“Oxidative stress is not something you want to have,” said Linda Birnbaum, a toxicologist and former director of the National Institute for Environmental Health Sciences. “This study increases our understanding that glyphosate has the potential to cause cancer.”

The study findings come after the CDC reported last year that more than 80% of urine samples drawn from children and adults contained glyphosate. The CDC reported that out of 2,310 urine samples taken from a group of Americans intended to be representative of the US population, 1,885 were laced with detectable traces of glyphosate.

Glyphosate is the most heavily applied herbicide in history, both in the US and globally. One of the best-known glyphosate-based products is Monsanto’s Roundup weedkiller. Roundup has been used by farmers as well as consumers for more than 40 years. Monsanto has always assured the public and regulators that exposure to the weed killer does not pose a threat to human health, but many independent scientists say there is a wealth of evidence to contradict those assurances.

People are exposed to glyphosate by using products made with the chemical and also by eating food and drinking water contaminated with the pesticide. Scientists have found glyphosate residues in an array of popular foods and in waterways across the US.

Notably, in the new paper, the NIH and CDC scientists said that while their study focused on farmers who were exposed to glyphosate when they sprayed it on fields, they saw similar results in “non-farmers.”

The findings suggest “these effects may apply more broadly to the general population who are primarily exposed through ingestion of contaminated food and water or residential applications,” the study authors wrote.

The study is so significant that it warrants regulatory attention, said some independent scientists.

“This is a top level team of investigators and a highly credible study to which regulators need to pay attention,” said Phil Landrigan, a pediatrician and epidemiologist who worked for years at the CDC and the Environmental Protection Agency (EPA) and now directs the Program for Global Public Health and the Common Good at Boston College.

Michael Antoniou, a scientist with the department of medical and molecular genetics at King’s College in London who has been researching glyphosate for years, said the results were “worrying,” with “major health implications.”