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Q&A with UNBC prof studying long-term effects of glyphosate spraying on forests

Picture a helicopter flying over a cutblock, releasing a misty cloud from a sprinkler-like contraption rigged to its belly. The cloud contains a herbicide called glyphosate. Every year, B.C.
Ecosystem Science and Management Assistant Professor Dr. Lisa Wood conducts field work into the impact of glyphosate-based herbicide use.

Picture a helicopter flying over a cutblock, releasing a misty cloud from a  sprinkler-like contraption rigged to its belly. The cloud contains a  herbicide called glyphosate.

Every  year, B.C. sprays about 10,000 hectares of forests with glyphosate as  part of its reforestation program. The practice, which is also common in  other parts of the country, gives replanted conifers a better chance to  grow by killing competing plants like aspen and birch. 

Glyphosate,  best known as the active ingredient in weed killer Roundup, is approved  by Health Canada for use in agriculture and forestry. Several  organizations and researchers have raised concerns about glyphosate’s potential effects on human health,  linking it to cancer, infertility, liver disease and other ailments.  Thousands of people have filed lawsuits against Bayer (formerly  Monsanto), the company that makes Roundup, claiming it caused them to  develop non-Hodgkin’s lymphoma. Studies have also shown glyphosate has toxic effects on earthworms, insects, amphibians and other aquatic species.

In a 2019 statement addressing concerns with glyphosate, Health Canada said “no pesticide regulatory authority in the world currently considers  glyphosate to be a cancer risk to humans at the levels at which humans  are currently exposed,” though it did not mention concerns about other  health issues or other species.

Critics, like the BC Wildlife Federation, say spraying glyphosate on forests does more harm than good. Removing competing plants can make forests more susceptible to wildfire,  and the herbicide also kills other vegetation that animals like moose  rely on as a food source. The province has been conducting studies on  the impacts of glyphosate on moose populations for the past two years  and expects to have results this fall.   

Little is  known about glyphosate’s long-term effects on plants and the wider  forest ecosystem. Lisa Wood, a plant biologist and assistant professor  at the University of Northern British Columbia, recently received  funding from the Natural Sciences and Engineering Research Council of  Canada to continue her work researching the effects of glyphosate on  forest ecosystems, particularly forests in northwest B.C. As a  scientist, Wood is trying to deepen the understanding of the effects of  glyphosate to inform future decisions. 

The Narwhal asked Wood some questions about glyphosate and her ongoing research.

What is glyphosate, and how and why is it used?

Glyphosate is the active ingredient in a number of different herbicides. It’s in formulations such as Roundup.

It is used  to get rid of any unwanted plant. It basically interrupts a metabolic  pathway within a plant and prevents the production of certain amino  acids and other things that the plant needs to survive. By cutting off  that pathway, it kills the plant. 

It’s used  in agriculture to get rid of weeds. It’s used in many different  communities to get rid of invasive plants. And it’s used in forests to  get rid of competing vegetation — any kind of vegetation that will  directly compete with our coniferous trees that are being grown for  crop. It’s also used sometimes on pipelines and different right of ways  to keep those pathways clear.

How did you first become interested in glyphosate?

I have an  undergraduate degree in forestry and after graduating I worked in the  industry for a few years. During that time, and throughout my education,  I was exposed to all the different tools that forest managers use,  including herbicides. I was always interested in [glyphosate] use and  what impacts there could be. It always surprised me that there wasn’t  that much information available about using different chemicals. I  didn’t feel like I was given enough information about positives or negatives.

What would you say to claims that glyphosate poses no risk to ecosystems?

The  assessment of what is risky is always interesting. Decision-making  bodies and decision makers are always making their best decisions based  on the knowledge of the day. And actually there is a lot of research  done on glyphosate, especially with regard to its toxicity to humans and  its toxicity to large mammals. The pest management regulatory authority  for Canada and many other countries in the world have deemed it  low-risk and have approved it for use because it’s considered to be non-lethal to humans. If your overall goal is human health, it’s not going to make anyone keel over and die.

But if  you’re going to look at smaller organisms, there is evidence that there are toxicity effects at certain doses. If you read the documentation  that the government puts out when they make their assessment, they say,  ‘OK, yes, this is low risk,’ but they will include a statement in there  that says it’s acknowledged that there are effects to some fish species,  insects and other small organisms, or something to that effect. 

They’re balancing economy and environment, like always, and they’re making the  best decision that they can make. In their view, obviously the  advantages of its use outweigh the disadvantages.

However,  my research is being done because I don’t feel like all of the  information is out there. We don’t have a clear picture of how long  glyphosate residues persist in forested environments. They degrade over  time, but we don’t know how long until they disappear, and we also need  to know how the communities or ecosystems as a whole are affected, which  is very difficult to assess. We have a good idea of individual organism  tolerance, but not how it works all together and over time.

We are  making the decision based on only a limited amount of research. And my  goal is to increase the pool of research available. The research might  show that yeah, you guys are making the right choice, or the research might suggest something else that gives people a chance to reevaluate.

In your previous work, you found that glyphosate can persist in  edible and medicinal plants that are unintentional recipients of the  chemical. What are the potential health implications of this?

I don’t touch health with a 10-foot pole! I’m a plant biologist, so I study what  happens in the plant and I’m going to leave what happens in other  organisms to other people.   

However,  the paper itself talks about residue levels in different plants that  could be food plants. I studied all the understory vegetation. These are  species that are usually not the targeted species but have received a  little bit of spray drift. Imagine the chemical falling down from a  helicopter or a plane and landing on the aspen it’s supposed to be  targeting. Obviously, there are spaces between the aspen, so whatever is  coming down and doesn’t get caught by the aspen will get absorbed by  the other plants that are in the area.

Those plants, because they’re not getting a full lethal dose, quite often  survive and the glyphosate stays in them. What we’re trying to figure  out is when a plant holds on to the glyphosate, what does it do with it?  Where does it go in the plant? How long does the plant retain it? 

If it’s a  deciduous plant, some glyphosate can be lost every year with the leaves.  But if you have a perennial species that’s only retaining its root  through the winter, the glyphosate is going to be in the root. When the  spring hits and the chute starts to grow, the glyphosate is going to go  up with other sugars and then that shoot is going to die and some of the  glyphosate will be lost and some will go back into the root.

We’re just  trying to figure out how long it actually stays there. Is it even a  concern, or does it not make any difference at all?

We are  finding some interesting things. We notice that right after application,  within the same growing season as application or even just shortly  after the next growing season, you see morphological deformations. For  example, where a normal leaf would branch out, you might have one really  nice big leaf, but instead of that you would have multiple tiny little  leaves shoot out from the same spot.

It might  seem like a really small thing, and that’s probably why it’s been  overlooked up to now. But if you start to see that across multiple  cutblocks, we don’t know what kind of effect that might have.

You recently received grants to further study the long-term  effects of glyphosate on forest ecosystems. What is the focus of the  work you’re doing?

There are  two grants. One is for three growth chambers. A growth chamber is  essentially a controlled environment. You can put plants inside it and  you can change the environmental conditions. 

The reason  we’re hoping to be able to control conditions is because there is a  hypothesis out there about glyphosate degradation changing depending on  environmental temperature. We think that perhaps in colder environments,  glyphosate breaks down more slowly than in warmer environments, which  makes sense because  glyphosate  is broken down by soil microbes. These organisms will eat more when they  are more active — we suspect they are more active in warmer  temperatures. Therefore, more activity in warmer temperatures means  glyphosate gets eaten faster and broken down faster. So it kind of makes  sense, but it hasn’t been really tested all that rigorously. 

The other  grant is for studying some specific things that I proposed. A large  portion of that money will go towards employing graduate students to be  able to engage in the research. 

We are  using fluorescence and microscopy to look at flower development and  form. We will also look at [whether] flowers [that have been treated  with glyphosate] are equally attractive to pollinators. To do this, we  will shine filtered light and UV light at the flowers to see them in a  different way — this is how scientists think that bees and other  pollinators see flowers and is part of how bees are attracted to them.  Certain flower parts “shine” under UV light. Scientists think that  pollinators are attracted to this shine. We want to see if flowers still  shine in the same way after glyphosate residues are present in tissues.  If they do not shine as much, then potentially bees can’t see them as  well or won’t identify them as a viable flower to get pollen from. This  is a hypothesis of course — we still need to test it!

We’re going to see if fungi are also affected by glyphosate. Some types of  fungi are very important to plants because they help plants access more  water and nutrients from the soil. Without these fungi, many forest  plant species would be unable to live. To study if fungi are affected by  the presence of glyphosate residue in plants, we will measure the  amount of fungus and identify the species of fungus present in the soil  around plants that have been sprayed compared to plants that haven’t  been sprayed. 

We are  hoping to determine if there is a difference in the way that plants grow  for years after glyphosate has been sprayed, and if this may interrupt  normal ecosystem functions — for example, the amount of food or habitat  that is available for animals. We also want to determine how long these  effects last and where they are found.

What impact do you hope your research will have?

I hope  that people can use the research to inform decisions and it doesn’t just  sit in some academic publication and never get used. It may inform  decision makers so that they can conduct a more thorough risk-benefit  analysis [which] may include where and when glyphosate-based herbicides  are applied in forests. There may be limiting factors or sensitive areas  that are identified, which may lead to a need to use alternative  methods of vegetation management in some managed forest areas.

I do  understand the driving force behind the use of glyphosate. I am a  forester as well and I was trained in forestry, and there are areas that  are very difficult to regenerate. Foresters legally have to regenerate  the cutblocks that are cut. So I do understand why that tool is used.   

I’ve been contacted by a huge number of people about just the one article [on  glyphosate in edible and medicinal plants] that I have published so far.  So a lot of people are looking for this research.

I do know  that some of the forest licensees in our region have been facing quite a  lot of public pressure to stop spraying practices or to alter or  decrease them. First Nations groups as well as some other societies and  organizations in this region, such as the guide outfitters association, are  interested in seeing spraying practices decrease. Perhaps those groups  are hearing the research and then that’s why they’re responding. 

In the wider conversation around the use of glyphosate on B.C.’s forests, what would you say is oversimplified?

I don’t  know what’s being oversimplified, but I can tell you there’s a lot of  misinformation out there. I hear a lot of people say things that I have  to correct. Glyphosate is a chemical just like everything else. When  people hear the word chemical, it makes them cringe. People think  chemicals are not natural things. But your body is composed of  chemicals; every organism in the world and everything in the world is  composed of chemicals. 

If you  don’t have a good understanding of ecological processes and if you don’t  have a good understanding of how a chemical might behave — like how  chemicals come together and react in environments — then it’s extremely  difficult to understand how glyphosate would impact an environment or  what effect it might have, or what lack of effect it might have.

The first thing that people commonly say to me is, ‘Well, the moose that’s walking  through the forest might have eaten glyphosate and then I eat the  moose, so I’m going to get glyphosate from it.’ And there are so many things wrong with that.

Glyphosate  doesn’t bioaccumulate. It’s actually water soluble, so it moves through  water. So it can’t be in something like the body fat of an animal. It  would be in the animal’s blood or the urine of the animal.

I think  ecosystem-level processes and complexities are very difficult to  understand. And most of us are only just chipping away at trying to  understand all of these things. Some of that is oversimplified. In  general, there’s a lot of misinformation out there about the negative  side of glyphosate and also the positive side of glyphosate.