Glyphosate Factsheet: Unwanted Impacts

The herbicide glyphosate not only kills plants but may also be harmful to animals and people. Caroline Cox compiled a factsheet for Journal of Pesticide Reform (v.108, n.3, Fall 1998 rev. October 2000):

Glyphosate is a broad-spectrum herbicide widely used to kill unwanted plants both in agriculture and in nonagricultural landscapes. Estimated use in the U.S. is between 38 and 48 million pounds per year. Most glyphosate-containing products are either made or used with a surfactant, chemicals that help glyphosate to penetrate plant cells.

Glyphosate-containing products are acutely toxic to animals, including humans. Symptoms include eye and skin irritation, headache, nausea, numbness, elevated blood pressure, and heart palpitations. The surfactant used in a common glyphosate product (Roundup) is more acutely toxic than glyphosate itself the combination of the two is yet more toxic…

Glyphosate has been called “extremely persistent” by the U.S. Environmental Protection Agency, and half lives of over 100 days have been measured in field tests in Iowa and New York. Glyphosate has been found in streams following agricultural, urban, and forestry applications…

Glyphosate is the seventh most commonly used pesticide in U.S. agriculture, the third most commonly used pesticide on industrial and commercial land, and the second most commonly used home and garden pesticide…

Glyphosate is often portrayed as toxicologically benign: “extensive investigations strongly support the conclusion that glyphosate has a very low level of toxicity…[73] NCAP’s review of glyphosate’s toxicology comes to a different conclusion..

…Glyphosate exposure has been linked to reproductive problems in humans. A study in Ontario, Canada, found that fathers’ use of glyphosate was associated with an increase in miscarriages and premature births in farm families.[87] (See Figure 5.)

…In 1991, EPA alleged that Craven Laboratories, a company that performed studies for 262 pesticide companies including Monsanto, had falsified tests.[94] “Tricks” employed by Craven Labs included “falsifying laboratory notebook entries” and “manually manipulating scientific equipment to produce false reports.”[95] Roundup residue studies on plums, potatoes, grapes, and sugarbeets were among the tests in question.[96]

…Although the tests of glyphosate identified as fraudulent have been replaced, this fraud casts shadows on the entire pesticide registration process…

…In general, movement of a pesticide through unwanted drift is “unavoidable.”[105] Drift of glyphosate is no exception. Glyphosate drift, however, is particularly significant because drift “damage is likely to be much more extensive and more persistent than with many other herbicides.” [106] This is because glyphosate moves readily within plants so that even unexposed parts of a plant can be damaged. Damage to perennial plants (when not exposed to enough glyphosate to kill them) is persistent, with some symptoms lasting several years.[106] In addition, plant susceptibility varies widely. Some wildflowers are almost a hundred times more sensitive than others; drift in amounts equal to 1/1000 of typical application rates will damage these species.[107]

A simple answer to the question, “How far can I expect glyphosate to travel off site?” is difficult, since drift is “notoriously variable.”[108] However, extensive drift of glyphosate has been measured since the 1970s when a California study found glyphosate 800 m (2600 feet) from aerial and ground applications. Similar drift distances were found for the 8 different spray systems tested in this study…[109]

Figure 7 Impacts of Glyphosate on Nontarget Animals on Maine Clear-cuts

Santillo, D.J., D.M. Leslie, and P.W. Brown. 1989. Responses of small mammals and habitat to glyphosate application on clearcuts. J. Wildl. Manage. 53(1):164-172.

Glyphosate treatment reduced invertebrate and small mammal populations for up to 3 years…

Repeated applications of glyphosate reduce the growth of earthworms.

… Beneficial insects kill other species that are agricultural pests. The International Organization for Biological Control found that exposure to freshly dried Roundup killed over 50 percent of three species of beneficial insects: a parasitic wasp, a lacewing, and a ladybug. Over 80 percent of a fourth species, a predatory beetle, was killed.[138]

…over 50 percent of test populations of a beneficial predatory mite were killed by exposure to Roundup.[138] In another laboratory study, Roundup exposure caused a decrease in survival and a decrease in body weight of woodlice. These arthropods are important in humus production and soil aeration…[143] The water flea Daphnia pulex is killed by concentrations of Roundup between 3 and 25 ppm.[144 -141]

…Mycorrhizal fungi are beneficial fungi that live in and around plant roots. They help plants absorb nutrients and water and can protect them from cold and drought.[173] Roundup is toxic to mycorrhizal fungi in laboratory studies. Effects on some species associated with conifers have been observed at concentrations of 1 part per million (ppm), lower than those found in soil following typical applications.[174, 175] In orchids, treatment with glyphosate changed the mutually beneficial interaction between the orchid and its mycorrhizae into a parasitic interaction (one that does not benefit the plant)…[176]

See also:

Herbicide Caution: Glyphosate Use May Damage Woody Plants
“Glyphosate should not be used to remove suckers, there should be a
30-foot buffer between the weeds you are spraying and the woody plants,
and glyphosate should not be applied so frequently,” said [Hannah Mathers, an Ohio State University Extension nursery and
landscape specialist].

Japanese Knotweed and Multiflora Rose: Is Herbicide the Answer?
[Japanese knotweed:] Once established, F. japonica is very difficult to eradicate and removal efforts may have further adverse impacts on the soil or other plants…

[Multiflora rose:] Where plants have become well established, a huge seed bank develops
that can continue to produce seedlings for at least twenty years after
removal of mature plants…

Based on the longevity of the seed bank, eradication might be a 20-year
project or more, far longer than the year or two (or even 10)
contemplated in Kohl’s latest written proposal.
It seems unreasonable and unrealistic to ask a developer and the
Conservation Commission to implement and monitor such a lengthy
program, especially when non-compliance with wetlands agreements has proven to be a widespread problem in Northampton.

contrast to a relatively short program of toxic
herbicides–extraordinary or not–the long-term, low-risk,
environmentally gentle solution to these invasive species appears to be
bringing the ecology back into balance, allowing and in some cases
encouraging the natural predators of knotweed and multiflora rose to
feast on their abundance. Additionally, preserving mature trees will
help control knotweed.

Gazette Reports on January 22 Kohl Condo Hearings; Pictures of the Latest Proposal; Conservation Staff Report; HYLA Critique

[Dr. Bryan Windmiller:] …the applicant proposes to mitigate the impacts of buffer zone
disturbance by disturbing even more area of inner buffer zone and
forested wetland itself.  This mitigation effort will, in fact, only
worsen the impacts to the wetlands bordering Millyard Brook…

The intended use of herbicides by the applicant to control Japanese knotweed (Polygonum cuspidatum)
will moreover result in the pollution of the wetland with herbicides
and their toxic surfactant agents.  The commonly used herbicide
glyphosate (Rodeo and Roundup) has been shown to be highly toxic to
amphibians, for example, in numerous papers by Rick Relyea and
colleagues (see summary at:   Japanese knotweed and multiflora rose (Rosa multiflora)
are furthermore difficult to eradicate, even with herbicides.  To do so
will require significant doses of herbicide applied many times.

the end, such schemes are likely only to result in further degradation
of the wetland system.  How long will the applicant continue to remove
exotic species and replace dead shrubs and trees that are planted in
the mitigation areas?  Three years?  Five?  Ten?