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Roundup Surrounds Us–What’s Next?

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Roundup: Latest Studies & Effects

The Popular Weed Killer and Herbicide, Roundup

roundup weed killerWith almost any chemical in widespread use, we don’t have the full picture of what we’re dealing with, even as our habitat practically swirls with a chemical stew. Most understanding of long-term health effects is not fully conclusive, because trials are usually done in labs on small rodents, and the human and ecological effects haven’t been adequately mapped over a sufficient time period. Many pesticides and their chronic effects on us are not comprehensively charted under a range of conditions, and may not be for some time.

Compared to most of the chemicals out there, glyphosate (usually sold as Roundup), has been considered pretty benign. The pathway through which it acts on plants doesn’t exist in most animals, since animals don’t have the enzyme that glyphosate targets in plants.

A broad-spectrum herbicide designed to complement a handful of crops genetically engineered with resistance to it, glyphosate has become the most widely used weed-killer on the market. The great majority of the corn, soybeans, and cotton grown in the U.S. are part of the Roundup Ready system.

But several studies have come out recently pointing to the growing number of superweeds resistant to it, and some began to wonder how effective and reliable it will be in the long term. These fast-growing resistant weeds can choke out crops in some places, and many farmers aren’t sure what chemical to use instead, since Roundup has so widely become the one-shot fix for what used to be a multi-herbicide job.

A new study by the U.S. Geological Survey (USGS) revealed the almost ubiquitous presence of the chemical in air and water samples, a finding that shouldn’t really surprise anyone, given the fact that over 88,000 tons of it are used each year in the U.S. The study was, however, one of the first to document consistent occurrence of glyphosate in streams, rain, and air over the course of the growing season.

USGS scientists say that many more tests are needed to determine how harmful glyphosate is to humans and animals. The great paradox of the herbicide is how little it’s actually studied, compared to its overwhelming use. It can be difficult and costly, though, to test for the presence of glyphosate.

The EPA is in the process of reviewing glyphosate’s registration, and has until 2015 to decide whether it can continue to be sold, or whether it has to be more restricted.

So, glyphosate is everywhere, at least in heavily-farmed areas like the Mississippi River Basin during the growing season. So far, at least, there’s been no evidence of acute toxicity or heavy persistence in soil or water. It has been classified as posing no carcinogenic threat. But we still don’t know much about what it does to people who are exposed to it on a regular basis, over the course of a lifetime, or to the sustainability and structure of an ecosystem.

Its record provides quite the contrast to potent, highly toxic pesticides that have exhibited effects more clearly linkable to the source within short periods of time, and were nonetheless approved by regulators, such as the fumigant methyl iodide (approved as a substitute for methyl bromide and used by California strawberry growers). With methyl iodide, inhalation is a direct threat to farmworkers, resulting in teratogenic effects on pregnant women, and probably developmental effects on nearby school children and children of farmworkers. These effects are often visible almost immediately.

glyphosate, roundupGlyphosate is a far more subtle case, having waited almost two decades to surface on our national threat radar, and in ways no one was quite looking for. And now, once we find out that it’s filtering into many essential corners of our environment, the next question is, how problematic is that? Certainly not as bad as if glyphosate were one of hundreds of other more dangerous legal chemicals out there. Will it be a threat to the long-term health of our soil, water, human and animal life? Will a cumulative effect emerge later, even if none is apparent now?

Glyphosate appears to be more inert than many of its counterparts. (This was originally a major part of its widespread appeal – it could be so widely effective on so many different weeds, seemingly with no other side effects.) Paul Capel, head of the agricultural chemicals team at the USGS office and a lead scientist in the USGS study, said that “the direct toxicity of glyphosate to humans and animals is very low, so the direct effect is not significant.” Where the research is needed is to determine the effects of long-term, low-level exposures. Some sources say it has been linked to spontaneous abortions in livestock and birth defects in humans, and that regulators have known this information for years, but have concealed it.

Earlier studies suggested that the mechanism of action in mammals was uncertain, but that the suspected effects – after long exposure times at low levels – were teratogenic (resulting in miscarriages or birth defects.)  A 2005 study found that Roundup was more toxic than its active ingredient alone, probably a result of the surfactants used in the formulation. Indeed, most health effects seemed to come from exposure to those chemicals.

A 1998 report by the California Department of Pesticide Regulation described glyphosate as having low mobility and low volatility – it had a low leaching potential in soil, and would be inactivated through soil adsorption, or adhesion to soil and sediment particles. Sediment would be a major sink for glyphosate, said the authors. Glyphosate is highly water soluble, but the rate of degradation in water would be slower, since there would be fewer microorganisms than in most soils to break it down. In streams, the residue was undetectable after 3 to 14 days. Its central properties, in fact, are that it is stable to sunlight, non-leachable, and has a low tendency to runoff.

The National Pesticide Information Center of Oregon State University Extension Service says that it also has a low tendency to bioaccumulate, since animals excrete it relatively unchanged, rather than metabolizing it or retaining it in their tissues, which would seem to make it nontoxic to most animals. The NPIC does mention the risk of late spontaneous abortion for pregnant women. Additionally, since it adsorbs so strongly to soil, there is little potential to contaminate groundwater or be taken up by plants – it mostly stays in soil and breaks down there. Its low vapor pressure also makes it unlikely to volatilize.

So the literature up to now has suggested glyphosate is relatively harmless. The true test of this, of course, is what happens as it starts showing up throughout the environment and finds its way into our bodies through multiple means on a regular basis. Paracelsus famously said “the dose makes the poison,” and we may find out before too long what that dose will be. The poison is likely to manifest as an indirect effect – for example, the inability to control our own weeds (and thus the inability to grow enough food), since they have begun to evolve in the presence of a single herbicide and few other strategies weed control. Or it could be biological effects that will only surface after half a lifetime of consistent exposure.

Genevieve Slocum is a Contributor to The Free George.

The Free George is the online magazine and visitors’ guide of Upstate NY, covering things from Albany to Lake Placid, including Saratoga, the Lake George region and the Adirondacks. Check out our new City Blogs section for our extended coverage areas as well.

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