Backgrounder

                                                              Glyphosate and Wildlife

                                                              December, 2002



Monsanto Company



Overview



Before any herbicide can be registered for use in the United States, the active ingredient must

undergo a number of required studies to investigate the potential for unreasonable adverse

effects to wildlife and other non-target organisms. The required studies are conducted with

species representative of various forms of wildlife � small mammals, birds, fish, aquatic

invertebrates, algae and aquatic plants, and honey bees. The results from these required

studies indicate that glyphosate will not cause unreasonable adverse effects to wildlife when

used according to label directions. In 1993, when glyphosate was reregistered in the U.S., the

Environmental Protection Agency (EPA) stated: “Based on current data, EPA has determined

that the effects of glyphosate on birds, mammals, fish and invertebrates are minimal� (U.S. EPA

1993).



In addition to studies required by the U.S. EPA and other regulatory bodies, many other wildlife-

related studies have been conducted with glyphosate products during more than 30 years of

use. The weight of evidence from these studies supports the conclusion from regulatory studies

that no unreasonable adverse effects are predicted from the normal use of glyphosate

herbicides (Sullivan and Sullivan, 2000). Glyphosate herbicides are commonly used as a tool to

restore and protect habitat. For example, they have been used in protected habitats such as

the Galapagos Islands and the Florida Everglades.



In 2000, three internationally recognized experts in environmental toxicology published an

ecotoxicological assessment of glyphosate and the original Roundup1 herbicide (Giesy et al.,

2000). Using very conservative assumptions, the authors established hazard quotient (HQ)

values for the various life forms that could be exposed to the formulation and glyphosate in the

environment, for both acute and chronic exposures. An HQ lower than 1.0 indicates minimal

risk of adverse effects, while HQ values greater than 10 suggest significant risk. The experts

found that no terrestrial use of the formulated herbicide produced an HQ of 1.0 or greater. They

also found that no aquatic use produced an HQ greater than 1.0, with the exception of

glyphosate and surfactant applied directly to very shallow water (6 inches). The highest HQ in

such shallow water was only 6.19. The authors point out that in actual use, aquatic vegetation

would intercept at least 50 percent of the applied product. As a result, the authors concluded

that direct applications of the original Roundup1 herbicide to water could be carried out with

minimal risk to aquatic organisms with consideration of the water depth, vegetation density, and

overall rehabilitation goal.2







1

  “Roundup� refers to the original single active ingredient Roundup herbicide formulation (also known as MON 2139).

2

  Only specific glyphosate formulations are labeled for aquatic use in certain world areas. Use of a product

                                                                                        TM

inconsistent with its label is a violation of law and is strictly prohibited. AquaMaster herbicide is labeled for aquatic

uses in the United States.









Backgrounder � Glyphosate and Wildlife. 2002.                                                               Page 1 of 5

Wild mammals



Glyphosate and Monsanto’s glyphosate herbicides have been extensively tested for adverse

effects on laboratory mammals, primarily rats, mice, and rabbits. In addition to laboratory

studies, the scientific literature contains many field studies in which the effects of glyphosate

use on wild mammals have been examined (Sullivan and Sullivan, 2000; Santillo et al. 1989;

Hjeljord et al. 1988; Sullivan 1990; Hjeljord 1994; Cumming et al. 1996; Cole et al. 1998).

These studies indicate that glyphosate and glyphosate herbicides, when used according to label

directions, will not cause unreasonable adverse effects to mammals. An ecotoxicological risk

assessment of glyphosate (Giesy et al. 2000) reported estimated exposures that various

mammals might encounter from potential use of glyphosate. The authors concluded that

mammals, including the tiny meadow vole, would not be expected to encounter harmful levels of

glyphosate through multiple possible exposure routes, including food, water and direct contact.



Birds



Glyphosate has been evaluated for toxicity to bobwhite quail and mallard duck in laboratory

studies. These species are surrogates for wild avian species that might be exposed to

glyphosate through various exposure routes. In dietary studies conducted with bobwhite quail

and mallard ducks, in which the birds consume treated diet for 5 days, glyphosate had no

effects at the highest dose tested. Reproductive tests indicated that no adverse effects on avian

reproduction or hatchling development would be expected from normal use of glyphosate.

Exposure of birds to glyphosate in the environment is predicted to occur at much lower levels

than the levels evaluated in the laboratory studies. In addition, glyphosate has been shown to

rapidly dissipate from treated vegetation, and such vegetation becomes unpalatable within 1 to

3 weeks after treatment. Therefore, the proper use of glyphosate-containing herbicides is not

expected to pose a significant risk to birds (U.S. EPA 1993). In addition to the laboratory

studies, several comprehensive field studies have examined birds in natural settings where

glyphosate products were used. These studies demonstrate that some species favored treated

areas, while other species temporarily left treated areas because of changes in the vegetative

habitat. No direct toxicity was reported in any of the studies (Giesy et al, 2000). Any form of

vegetation removal would be expected to produce similar effects. Studies have shown that

avian species abundance returns to pre-treatment levels when plant regrowth occurs

(MacKinnon and Freedman, 1993).



A Technical Information Summary titled “Glyphosate and Avian Species� is available upon request from

the Monsanto’s Public Affairs Director for Agricultural Chemicals at 314-694-3546.



Aquatic animals (fish, shellfish)



Glyphosate and many of Monsanto’s glyphosate formulations have been tested for toxicity to

numerous aquatic animals, including invertebrate and vertebrate fresh and saltwater species.

Results of these studies indicate that glyphosate has very low acute toxicity to aquatic animals

(U.S. EPA 1993, WHO 1994) Levels required to produce adverse effects would not be

expected from labeled use of glyphosate herbicides. It has also been shown that glyphosate

does not bioconcentrate in tissues of aquatic organisms (WHO, 1994).



To work effectively, glyphosate must be mixed with a surfactant (a soap-like substance) that

facilitates the uptake of glyphosate by the plant. Surfactants may be more toxic than glyphosate

to aquatic organisms in laboratory tests. However, the level of surfactant present in a herbicide

application is sufficiently low that no unreasonable adverse effects are expected to result from





Backgrounder � Glyphosate and Wildlife. 2002.                                              Page 2 of 5

the normal use of the products. A conservative aquatic risk assessment indicates that

glyphosate and surfactant would not be expected to produce unreasonable adverse effects to

aquatic organisms in water 6 feet deep (Giesy et al, 2000). In more shallow water, potential

effects predicted by hazard quotients are unlikely to occur in the environment due to

interception, sediment binding, and degradation of the herbicide components. The World Health

Organization report on glyphosate states: "Fish and aquatic invertebrates would not be affected

by glyphosate use" (WHO 1994).



Amphibians



Toxicity studies with amphibians are not included in the standard toxicity tests required for U.S.

EPA registration. Toxicity studies with amphibians have shown that amphibians are not more

sensitive than fish to herbicides (Mayer and Ellersieck, 1986; Birge et al., 2000). Since fish are

included in the mandatory toxicity studies for pesticide active ingredients, amphibians are not.

Nevertheless, the toxicity of glyphosate and some glyphosate formulations to several species of

amphibians, including frogs, newts and salamanders, have been investigated. A risk

assessment based on exposure of amphibians and other aquatic organisms demonstrates that

normal use of glyphosate formulations are not expected to cause unreasonable adverse effects

to amphibians, including tadpoles (Giesy et al., 2000).



Insects and other terrestrial arthropods



Glyphosate and the original Roundup1 formulation have been tested for toxicity to honey bees in

laboratory tests, using both oral and topical dosing. In these studies, glyphosate and Roundup

were found to have no adverse effects to bees at rates much higher than would be present in

treated areas. In addition, the original Roundup formulation has been evaluated in laboratory

studies with terrestrial arthropods such as the parasitic wasp, predatory mite, carabid beetle,

and green lacewing. These laboratory studies use artificial exposure conditions to simulate

exposures in the field. When the results of these studies are compared to estimated residues of

glyphosate that might occur in and adjacent to treated areas, it can be concluded that the risk of

unreasonable adverse effects to terrestrial arthropods ranges from low to moderate. At the

maximum use rate, no in-field effects are predicted for the carabid beetle and parasitic wasp,

while in-field effects cannot be excluded for the predatory mite and green lacewing. However,

no effects to the predatory mite and green lacewing are expected at more typical use rates.



Habitat change resulting from herbicide use (due to the decrease in vegetation) can have a

significant influence on leaf-dwelling arthropod populations (e.g. wasp, mite, and lacewing). The

primary effect to populations on-site are expected to result from herbicidal effects on vegetation.

Therefore, direct effects on arthropod populations that might be observed after herbicide use

are expected to be less significant than effects due to habitat change.



The effects of other glyphosate formulations on beneficial arthropods may vary from those

observed for the original Roundup formulation. Generally, no effects are observed to beneficial

arthropods at rates expected from herbicide drift to nontarget areas. In target areas, habitat

change is expected to have the most influence on arthropod populations.



In a screening assay in which 18 different beneficial predators and parasites were exposed to

the original Roundup1 formulation on a synthetic surface, the formulation was found to be

“harmless� to 13 species, “slightly harmful� to four species and “moderately harmful� to one

species (carabid beetle) (Hassan et al. 1988)a. The authors did not believe that sufficient

toxicity potential existed for the Roundup formulation to warrant semi-field and field tests that







Backgrounder � Glyphosate and Wildlife. 2002.                                            Page 3 of 5

were performed on some of the other compounds tested in the same program. A subsequent

semi-field test with a similar glyphosate formulation indicated that even when carabid beetles

were directly oversprayed at the maximum use rate, no mortality was observed. One reason for

the difference between the laboratory and semi-field study results may be related to the artificial

nature of the laboratory glass plate assays (e.g. potential stickiness of the formulation on the

glass substrate).



After reviewing extensive research on glyphosate and arthropods, three experts in

environmental toxicology wrote (Giesy et al., 2000):



         “In summary, the literature supports the conclusion that non-target arthropods

         are at minimal risk from glyphosate and its formulations in offsite areas. Within

         treated areas, applications of the herbicide can produce changes in species

         diversity and in population size and structure for beneficial insects through

         modifications of available food sources and habitat.�

a

 Categories used by Hassan et al. to report mortality/reduction in beneficial capacity were as follows:

“harmless�: < 50%; “slightly harmful�: 50-79%; “moderately harmful�: 80-99%; “harmful�: > 99%.



Earthworms



Numerous studies support the conclusion that normal use of glyphosate formulations, such as

the original Roundup herbicide1 and other glyphosate herbicides, will not result in adverse

effects to earthworms. A comprehensive review of the effects of agricultural chemicals on

earthworms reviewed the effects of glyphosate on earthworms (Edwards and Bohlen 1996).

Glyphosate was ranked as zero on a scale of zero (relatively non-toxic) to 4 (extremely toxic).

Monsanto and several independent researchers have conducted studies in which no adverse

effects were observed when earthworms were exposed to glyphosate residues in soil at rates

equal to or greater than labeled rates (Giesy et al., 2000). In field studies, it has been

demonstrated that earthworms thrive under conservation-tillage cropping practices, which are

facilitated by Roundup UltraMax and other glyphosate herbicides (Giesy et al., 2000).



A Technical Information Summary titled “Glyphosate and Earthworms� is available upon request from the

Monsanto’s Public Affairs Director for Agricultural Chemicals at 314-694-3546.



Soil microorganisms



Numerous laboratory and field studies have been published by independent researchers

investigating the effects of glyphosate on soil microbes. The weight of evidence from these

studies conducted using realistic exposure conditions indicates that no significant adverse

effects to soil organisms are expected when glyphosate herbicides are applied according to

label directions (Giesy et al, 2000). Experiments on glyphosate treated and untreated soil

revealed no significant difference in the types or amount of microbes present (Rueppel et al.

1977). Studies also show that glyphosate does not interfere with the ability of microbes to

decompose plant material, such as dead leaves, or convert inorganic nitrogen into an organic

form needed for plant growth (Grossbard, 1985; Sullivan, 1990).









Backgrounder � Glyphosate and Wildlife. 2002.                                                             Page 4 of 5

References



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   amphibians. Chapter 14A in Ecotoxicology of Amphibians and Reptiles. Sparling DW, Linder G,

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   727-791.

Cole EC, McComb WC, Newton M, Leeming JP, Chambers CL (1998) Response of small mammals to

   clearcutting, burning, and glyphosate application in the Oregon coast range. J Wildl Manage 62(4):

   1207-1216.

Cumming HG, Lautenschlager RA, Kelly CP, Thapa S (1996) Effects of conifer release with Vision®

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   Forest Research Report 139. Cited In: Sullivan and Sullivan 2000.

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Hjeljord O, Sahlgaard V, Enge VE, Eggestad E, Gronvold S. (1988) Glyphosate application in forest --

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                               th

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U.S. EPA (1993) Reregistration Eligibility Decision: Glyphosate. U.S. Environmental Protection Agency.

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