No matter who you are, you’ve probably heard the words “RoundUp” or “glyphosate” tossed around recently, whether it’s in your social media feed, the news or from a neighbor or friend. You may have heard about the controversial court cases in California or have seen your local garden stores stocking their shelves with the popular weed killer. You may have strong feelings or opinions already, or you may not. Either way, what’s the deal with RoundUp? 

I grew up on a cattle ranch and have been always been involved in the farming community, including managing two farmers markets on the Wasatch Front. Being involved in this environment, I have repeatedly heard from farmers and scientists that RoundUp is safe to use, and doesn’t negatively affect animals, the soil, or humans.

However, after several recent courts in California have ruled in favor of the plaintiffs’ claim that RoundUp caused their cancer, I started to have little whispers of doubt. That, combined with the fact that I am soon to be a mother and want my child to be as healthy as possible, led me to question what I thought I had known as fact.

What if RoundUp is harmful?

It IS classifieds as a “probable carcinogen” by the International Agency for Research on Cancer.

Could it be possible that I’m wrong?

In my search for answers, I started with the facts.

RoundUp is an herbicide, herbicides kill plants, specifically undesirable plants in crops and gardens. There are multiple herbicides available for farms and gardening, but RoundUp has received celebrity status and become widely used by farmers over the last 40 years.

One reason why it is so popular and effective in farming is because it can pair with certain crops called “RoundUp Ready”, which means they don’t die when RoundUp is sprayed on them. Their modified DNA produces an enzyme slightly different from the normal type, and it remains unaffected by glyphosate (the active ingredient in RoundUp). Un-modified plants, however, will die just like the weeds. This allows farmers to spray the herbicide (about a cup per acre, or the size of a football field) on an entire field and only the noxious weeds or other plants will die, not the crop.

So that is the science of how glyphosate works. But that doesn’t answer any of the bigger questions surrounding the herbicide.

I reached out to cell biologist, author and mother, Iida Ruishalme, to get some answers. Iida is originally from Finland and specializes in biomedical research with a Master’s degree from Sweden. She now lives in Switzerland with her husband and two children. I wanted to interview someone who studies plant chemistry, but who is also a mother with the same concerns and desires for her children’s health as me.

Iida Ruishalme, presenting at AtomExpo in Sochi 2019

Q: Can you explain in very simple terms, why glyphosate is harmful to plants but not humans?

A: Plants need to make pretty much all of their amino acids from scratch. That includes the so called 'aromatic' amino acids. Plants have specialized enzymes that help them form these structures - and glyphosate binds to that enzyme, so it can't function.

Humans (and animals in general) are different, we have never been able to make these amino acids on our own - they are among the so called 'essential' amino acids, which we must get through diet. So glyphosate's main action of impairing protein synthesis does not affect us. It's a bit like this: if you put up a good fence around your garden to stop rabbits from getting in, it will be effective. But it will be of no consequence to birds, because they use a wholly different mode of transportation. Plants (and many bacteria) are the rabbits of this metaphor, affected by the fence, and we are the birds that just swoop in and pick up what we need.

Q: Can you please explain what it means for a substance to be classified as a “probable carcinogen” by the IARC? Does that de facto mean that substance causes cancer?

A: ‘Probable’ does not refer to the fact that cancer would be probable through exposure, because the IARC categorization doesn't tell us anything about how strongly that substance might affect cancer risk. 'Probable' refers to the strength of evidence they consider there to be for drawing any conclusions. They say the evidence is probably sufficient for them to say whether it causes some level of increase in cancer risk in some circumstances. Whether that increase in risk is slight or huge, if it would result from common exposure levels, or would first show up if we were bathing in that substance daily isn’t something IARC tells us. The IARC doesn't try to make that kind of evaluation.

So being a 'probable carcinogen' is IARC's way of saying that the substance could probably increase cancer risk in certain circumstances. They are saying that things like very hot beverages, wood dust, shift work, and glyphosate (all in the probable category) could cause cancer in certain circumstances - that doesn't mean things like drinking tea or doing a night-shift, or using glyphosate, would be likely to have a large, or even any, effect on our cancer risk. However, life-long poor sleep patterns, repeated scalding, or drinking glyphosate might not be such good ideas (for many reasons, potential increase in cancer risk being only one of them).

Q: I’ve seen that other agencies, like the World Health Organization (WHO) and the United Nations Food and Agricultural Organization (FAO), have concluded that there is no reason to think normal exposure to glyphosate would be carcinogenic.1 If that is the case, why are courts in California ruling that it causes cancer?

A: There are many instances of layman juries getting things wrong, not only in scientific cases of course, but also in sentencing innocent people to jail, or even death. A small random group of individuals with no scientific expertise, drawing conclusions based on a limited set of arguments presented to them by lawyers, is not a valid method of determining the best scientific understanding on a topic. They can get things wrong.

Q: Why is that?

A: Why? Well, we humans are naturally inclined to sympathize more with the 'little person,' especially one suffering from an illness, who is going against a large and impersonal corporation, particularly when it's one of the most vilified companies you can find. It is very hard not to be biased toward a view that confirms our previous misconceptions in a setting like that.

Another difficulty here is the discrepancy between everyday logic and what I call ‘science speak’. When juries are shown scientific sources that conclude, say “substance x is unlikely to be a cancer risk,” that wording does not reassure them. They might easily think, “So it's unlikely... but possible?” Scientists rarely use the kind of absolute statements that would put a jury at ease, but actually, a scientist saying substance X is unlikely to even pose a risk is big. It might not sound like that because it's tempered by the strict scientific principles of never reaching absolute certainty.

Q: Is glyphosate detectible in breast milk?

A: There have been at least four studies that I know of that have looked at this2, and they all find no glyphosate in breast milk. The claim that it could be detected is actually sort of an urban legend, propagated by a mom-group whose core operating principle, sadly, is to spread scary rumors about food and medicine. Many of these moms are probably well-meaning, and I can sympathize with their concern.  We all want to find some easy culprit or an easy fix for how to be healthy and keep our kids healthy. But being a mom myself, I owe it to my kids and myself to acknowledge that sometimes things are not that simple, and it's important to learn more about things before jumping into conclusions or simply accepting scary-sounding stories as true.

Q: If farmers stopped using RoundUp and went back to other traditional herbicides, what effect would that have on farming and the environment?

A: It would have a really big impact. This is why I am so worried about these scary stories passed around among parents; because of the kind of environmental consequences it could have. If the popular fears of glyphosate lead to bans, there are real, serious downsides. Not only would we force farmers to go back to herbicides that actually are more harmful, but we would also see a big reduction in practices like no-till, which is one of the best tools for conserving soil. Should farmers be forced to stop using glyphosate and revert to more tilling as their method of weed control, the prospects of increases in fuel use, reduced sequestration of soil organic matter, increased nutrient leeching, and increase in emissions would be significant.

I remember a really gripping interview of a sugar-beet farmer, who reminisced the times of the 'traditional' regimen of constant herbicide sprays, and an army of people working sometimes round the clock to spray their fields, before they had glyphosate. He said if he'd have to go back to that, he might rather just quit. I really hope we don't make things harder for farmers to use environmentally friendly methods.

Q: One more question, mom to mom. Do you feel the need to buy organic food for your family? Why or why not?

A: I used to buy all organic, right up until when my first baby was about 6 months old. I mostly did it because I thought organic food had environmental benefits. Health-wise, I knew it didn't differ from conventional - both are safe and healthy. But then the environmental effects came up in an online discussion, and being trained as a scientist, I wanted to give the best scientific argument in favor of organic... and it was a bit of personal a crisis. I realized I had been assuming organic methods were based on evidence of benefits. My searches of the evidence left me empty-handed, however. It became evident that the organic approach was not based on looking for the best proven environmental benefits, it was a vague 'naturalness' principle, combined with some wishful thinking that these more natural-feeling methods must be better. Even when it meant that organic was starkly opposing methods that were proven to be environmentally beneficial, like genetically engineered crops. I was at a loss and felt foolish and betrayed. It led me to going from an organic shopper to someone avoiding the labels, if at all possible. 


Living in fear, and especially making purchasing decisions based on fear, is no way to live. After my interview with Iiada, I was so relieved to know that many of the concerns that I had were rational, but unfounded. Everyone can choose how they want to spend their money, but now I feel I can purchase my groceries and be comfortable in the knowledge that it was grown in a safe, healthy environment, and that I won’t inadvertently harm my growing family.

You can check out Iida’s work here: