Your question is timely. At this writing, in December 2017, the weed killer Roundup and its main ingredient, glyphosate, have been making news in the U.S. and Europe. A study from the University of California, San Diego found a 500 percent increase in the general population’s exposure to it during the past two decades. The researchers reached this conclusion after measuring urine concentrations of glyphosate in 100 seniors in southern California. The team first collected samples between 1993 and 1996 and more recently between 2013 and 2016. The difference was striking – only 12 percent of samples in the 1990s showed detectable levels of glyphosate, but the latest tests showed that the chemical was present in 70 percent.
The World Health Organization (WHO) classified glyphosate as a probable carcinogen in 2015, and this year (2017) California did the same and also required that products containing glyphosate carry warning labels on their packages.
We know that the use of Roundup has increased 15 fold since the 1990s. It is applied to many crops, including wheat and oats and genetically modified soy and corn. Glyphosate is also in other weed-killing products used on lawns and gardens nationwide. It is also widely used in Europe.
A review of human and animal studies published in 2016 linked exposure to glyphosate to liver and kidney damage, endocrine disruption and an increased risk of non-Hodgkin’s lymphoma. Most of the research was done in animals. Few human studies have investigated the health effects of glyphosate, and no federal agency monitors how much of it gets from the environment into us. It is difficult to determine how much is potentially harmful to humans and whether current exposure levels are above or below that mark.
Coincidently, findings from a National Institutes of Health-sponsored study published only a week after the one from UCSD found no association between glyphosate and most types of cancer among licensed pesticide applicators in Iowa and North Carolina. However, this investigation did see an increased risk of acute myeloid leukemia, a type of cancer that begins in the bone marrow, among applicators who had the highest exposure to glyphosate compared to those with no exposure at all.
The Environmental Protection Agency maintains that glyphosate is safe and in 2013 doubled allowable levels of the chemical on certain crops.
Bottom line: we don’t have much definitive health information about the risks posed by repeated or prolonged exposure to glyphosate (and most other chemical pesticides). I advise applying the precautionary principle. Opt for organically produced foods whenever you can.
Andrew Weil, M.D
Paul J. Mills et al, “Excretion of the Herbicide Glyphosate in Older Adults Between 1993 and 2016.” JAMA October 24/31, doi:10.1001/jama.2017.11726