Roundup part two: The environmental consequences of the world's most-used herbicide.
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Last week, The Green Dispatch looked at the possible health effects of Roundup, the ailments that the herbicide’s use might cause to humans. This week, I want to concentrate on the effects the herbicide may be having on the environment.
As it had been thought to break down quickly after its application, Roundup was assumed to have little effect on the larger environment outside of its agricultural uses. Once it was sprayed on the genetically modified sugar beets, corn, soybeans, or other crops developed to resist the herbicide, microorganisms in the soil or ultraviolet radiation would quickly break the herbicide down, making it harmless. But Roundup persists longer in the environment than the initially thought. And as long as nine years ago, evidence mounted that Roundup, and its chief ingredient, glyphosate, were contributing factors to the decline of amphibians. More recent research indicates that other classes of animals may also be harmed because of the herbicide.
Insects
Depending on what is being targeted for eradication, glyphosate will be concentrated at different levels, from as low as 1.5 percent for spot spraying of weeds, to around four to seven percent for large-scale spraying, and up to 100 percent to kill some woody plants.
A recent study from Johns Hopkins University exposed moths and mosquitos to very dilute concentrations of glyphosate (20 micrograms of glyphosate to one liter of water). This is a much lower concentration than the commercial application concentrations noted above and is a concentration corresponding to those found in some environments. The exposure limited the ability of the insects to produce melanin. Melanin is one of the pigments in human skin that gives us our different skin colors. The compound is also produced and used by insects to ward off pathogens. It follows from this research that insects in glyphosate tainted environments may be at greater risk of disease.
Microorganism in the guts of animals (humans, too) aid in the digestion of food and help in the regulation of other bodily functions, such as respiration and the functioning of our immune systems. Research from 2018 found that glyphosate inhibits the microbes that make their homes in the guts of honeybees. Scientists fed about 2000 honeybees a sugar syrup laced with glyphosate at levels they might experience in their environment. Bees that had eaten the glyphosate mixture had lower amounts of beneficial bacteria in their bellies. Surprisingly, bees that ate the most of the herbicide had more normal levels of bacteria. One of the scientists explained that this might be because a lot of the bees that got a higher dose died and skewed the scientific findings. This research was performed at the University of Texas Austin and published Proceedings of the National Academy of Sciences.
The next question is what kind of influence on gut health glyphosate might be having on other species. As the herbicide may be one of the reasons for the decline of honeybee populations, it may be part of the reason for the decline of native bee species in the United States, too. So far as I know, no science has been performed looking into a link between declining native bee populations and glyphosate, but I’m certain the time to look into it is now.
Fish and other aquatic creatures
In countries with a lot of agriculture, glyphosate and glyphosate compounds have been detected in waterways, with levels rising during rainy periods, as the rain leaches the herbicide compounds out of soils. A study conducted in the United States in 2020 measured glyphosate levels at stream sites throughout the lower 48. The researchers found Glyphosate in 66 of the 70 streams in the study. None of the concentrations exceeded benchmarks for human health or ecological disruption, but a compound that is a byproduct of glyphosate breaking down, aminomethylphosphonic acid, was found as commonly as glyphosate. There is no science on this substance’s safety.
Researchers in Texas studied Roundup and the tadpoles of the Rio Grande leopard frog, an amphibian that is found in New Mexico, Texas, Mexico, and Central America. They exposed tadpoles to different combinations of Roundup and antibiotics (which are flushed from households and also found in waterways). The tadpoles that fared the worst in the experiment were the ones exposed to both antibiotics and Roundup; they were the smallest and least active among treatment groups. Though they were about the same size as tadpoles that lived free of Roundup and antibiotics, tadpoles exposed to Roundup weren’t as active as the tadpoles in the control group. The scientists also found that Roundup and the antibiotics also affected the gut microbes of the tadpoles.
Scientists found troubling results in a recent meta analysis (where scientists examine the results of several scientific studies) of glyphosate and fish. All of the studies included in the analysis were performed on zebrafish, a fish native to South Asian streams. Zebrafish are the most commonly used fish in these types of experiments; they are the go-to fish for this type of research. The findings were published in the journal Water in June.
The scientists found that if you want to kill zebrafish, expose them to concentrations of 400 micrograms per liter of glyphosate for 24 hours or a concentration of 200 micrograms of glyphosate for 48 hours. Under these conditions ALL of the fish died, all of them. Exposing zebrafish eggs to glyphosate harmed them and their hatchlings, sometimes leading to malformed offspring, decreasing the size of the offspring, or leading to other defects, such as spinal curvature.
The herbicide affected adult zebrafish behavior. After brief exposure to glyphosate, the fish showed signs of anxiety, swam slower, and explored their surroundings less. They also weren’t as quick to recognize when a predator was about to attack. Roundup was even found to cause genetic damage within the cells of the zebrafish.
Despite acknowledging some ecological problems from using glyphosate, the U.S. EPA sends the message that the herbicide is largely safe, although the European Union is currently deadlocked on allowing its continued use.
What do you think? Is glyphosate risky? Even if it is, do our agricultural needs outweigh the possible harms to the environment? Is regenerative farming and organic farming—all performed without glyphosate or similar compounds—able to feed the billions who inhabit this planet? Let me know what you think. Just click the “Leave a comment” button below.
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Appreciate the information. Very useful in our knowledge of what's effects are happening in the world of agriculture and human consumption. Well done.
I have spoken to one of the executives at Rodale Institute. It really wasn’t much of a study more of an analyzation. They simply identify constituents with a mass spectrometer.