As you and other farmers are well aware, weed control is one of the keys to good yields. GM crops that can tolerate glyphosate, the active ingredient in Roundup agricultural herbicides, provide a simplified approach to weed control and allow farmers to rely on an herbicide with a thoroughly documented record of safe use. Glyphosate is well known for its low toxicity to humans, farm animals and wildlife.
From time to time, there are reports of glyphosate being detected in samples collected from people. It is understandable that reports like these capture the public¹s attention and raise some concerns. The important point to keep in mind is that regulatory agencies around the world devote a significant amount of effort to reviewing multiple sources of safety data before allowing any crop-protection chemical, including glyphosate, to be sold and used. These agencies will review toxicity data for the chemical and limit allowable use rates to ensure human exposures will be well below levels where adverse effects could occur. Comparing reported concentrations with these allowable levels makes it possible to determine whether adverse health impacts are likely to occur.
With respect to this specific allegation, it is likely that your landlord is thinking of a report from 2013 that looked at 182 urine samples collected from people in 18 European countries. There are other, similar reports, but this one received the most attention in the popular press. I am not aware of a report that examined glyphosate in blood from Europeans.
In this study, glyphosate was not detectable in most of the samples. The largest concentration detected (two parts per billion, or the equivalent of two cents in $10 million) corresponds to an intake 1,000 times lower that what is allowed in Europe and 3,500 times lower than the limit established by the World Health Organization. In other words, the study found that exposures were well within the limits set by agencies that have reviewed all available data on glyphosate to derive safe exposure levels. As the Centers for Disease Control and Prevention note, "Just because we can detect levels of an environmental chemical in a person's blood or urine does not necessarily mean that the chemical will cause effects or disease. Advances in analytical chemistry enable us to measure low levels of environmental chemicals in people, but separate studies of varying levels of exposure determine whether specific levels cause health effects."
This type of misinformation is exactly why GMO Answers was created. We understand people have concerns about GMOs, and we need to do a better job answering their questions.
We encourage you to take a look at and perhaps share several of the questions and answers on this website that discuss the safety of glyphosate,how glyphosate is applied and how trace levels of glyphosate are not toxic to humans. We also have information about how GM technology can reduce pesticide applications, including herbicides, insecticides and fungicides.
We invite you and anyone else you know who has questions about GMOs to participate in the discussion on GMO Answers.