Revised, January 1997 Sylvia Knight, compiler
This annotated bibliography on glyphosate, its formulations and other herbicides combines and updates my two previous bibliographies of January 1996 and August 1996, summarizing articles collected largely from scientific journals which submit their works to a jury of peers in an approval process. Each annotation includes authors, title of article, journal title and citation, and summary comments explaining why the article is important. Most of these articles are available at the University of Vermont Libraries (Bailey/Howe or Dana Medical), or through interlibrary loan. The bibliography concludes with citations from Vermont Statutes Annotated regarding the public trust of Vermont's waters. I have listed the articles alphabetically by author within subject areas: I. Toxicity for humans and other mammals
II. Impact on birds
III. Toxicity for fish, aquatic invertebrates, and amphibians
IV. Impact on microbial biomass, fungi, forest soils and plants
V. Forest management
VI. Water issues
I. TOXICITY FOR HUMANS AND OTHER MAMMALS
1. Arnold, Steven F., et al (1996) "Synergistic activation of estrogen receptor with combinations of environmental chemicals." SCIENCE, 272:1489-1492 (7 June).
Certain chemicals in the environment are estrogenic. Low potencies of these compounds when studied singly may indicate little effect on biological systems. However, combinations of two weak estrogen-mimicking chemicals were 1000 (!) times as potent as any chemical alone. This synergistic interaction of chemical mixtures with the estrogen receptor has profound environmental implications.
2. Clement, Coralie R. and Colborn, Theo, "Herbicides and fungicides: a perspective on potential human exposure." In Colborn, T. and Clement, C., CHEMICALLY INDUCED ALTERATIONS IN SEXUAL AND FUNCTIONAL DEVELOPMENT: THE WILDLIFE/HUMAN CONNECTION. pp347-364. (Princeton, NJ: Princeton Scientific Publishing, 1992)
In this chapter from their book, Colborn and Clement examine the issue of our increased exposure to pesticides (including herbicides and fungicides) and the difficulties encountered in obtaining any meaningful measurements of these exposures for women, children, even embryos in vivo. (Most standards of exposure are geared to the adult male.) Exposure (to active and so-called "inert" ingredients) through treated food and contaminated water are now combined with exposures through rainwater, snow, household dust, yard soil and indoor air. The timing of exposure, even to a small amount, can have a profound effect on an embryo. No studies showing cumulative exposure from all pathways could be found. There are many reproductive and endocrinological effects associated with herbicides and fungicides. The reassessment and reregistration of many older pesticides (using new techniques) mandated by law in 1988 had not been conducted in 1990. False claims about the safety of pesticides, combined with flaws in the federal registration process, raise serious concerns about increased exposure to environmental chemicals, when there is lack of information on their reproductive and endocrinological effects, synergy, bioaccumulation, and continual low-dose exposure.
3. Connor, J.F. and McMillan, L.M. (1990), "Winter utilization by moose of glyphosate-treated cutovers. ALCES 26:91-103.
This study compared moose forage resources on control and on herbicided cutovers near Thunder Bay, Ontario. Available moose browse, on control areas, was four times greater, and browse utilized was 32 times greater, than in treated areas after 1 growing season post-spray. Winter moose presence was almost two times greater on untreated than treated areas after 1 growing season and similar at 2 growing seasons post-spray. An important issue that needs to be considered is the effect of spraying sizable contiguous areas, substantially affecting food supplies within the home ranges of a number of moose, and the eventual effect on moose populations.
4. Cox, Carolyn (1992), "When ignorance is not bliss: secret 'inert' pesticide ingredients." JOURNAL OF PESTICIDE REFORM 12:3:1-5. The editor of the JOURNAL OF PESTICIDE REFORM discusses "inert ingredients" in pesticide formulations and some problems with their use and regulation. When applied to pesticides, the word "inert" does not mean biologically, chemically, or toxicologically inactive. It means substances other than the "active" or principal ingredient, and other than adjuvants added by the pesticide user. Inerts may be obtained from hazardous wastes, and belong to classes of chemicals that are linked to serious health or environmental impacts. EPA has grouped inerts into 4 lists, and regulates them differently according to the list on which they appear. Limited toxicity tests do not include chronic toxicity, reproductive effects, cancer, neurotoxicity tests, and most ecotoxicity and environmental fate tests. As of 1992, EPA could not produce a list of all ingredients found in pesticide products or which ingredients are found in specific products.
5. Martinez, T.T. and Brown, K. (1991), "Oral and pulmonary toxicology of the surfactant used in roundup herbicide." PROCEEDINGS OF THE WESTERN PHARMACOLOGY SOCIETY, v.34, p.43-46.
The surfactant POEA (in doses of 1.03g/kg ) has serious pulmonary toxicity, but not quite as serious as the full formulation, Roundup which produced 100% death in rat subjects within 24 hours. Recent cases of poisoning in suicide attempts using a 41% glyphosate concentration have produced life-threatening symptoms (in humans) and a DEATH RATE of 10-20%, in spite of animal studies which show that the active ingredient, glyphosate, has a toxicity of approximately 5g/kg.
6. Martinez, T.T. et al 1990), "Comparison of the toxicology of the herbicide Roundup by oral and pulmonary routes of exposure". PROCEEDINGS OF THE WESTERN PHARMACOLOGY SOCIETY, v.33, p.193-197.
This study involved male rats weighing 340-360g. The animals were anaesthetized and the herbicide was administered directly into the trachea. Roundup ready to use (RTU)(1% glyphosate plus .4% POEA) produced 60% death in 24 hrs at the .2ml dose and 80% death in 24 hours at the .4ml dose. Roundup 18% concentrate produced even more severe effect with 80% death at .1ml and 100% death at both .2 and .4 ml. (The stronger formulation proposed for forestry in Vermont, 41.5% glyphosate plus 15% POEA, was not tested in this study.) General observations were as follows: blood stained fluid or foam was seen to come out of the nose; heavy breathing sounds, rhonchi, wheezing, and gasping for air; death usually occurred within 3 minutes (for higher doses). Animals found dead the following morning showed evidence of diarrhea, loss of yellow or blood stained fluid from the mouth, edema of stomach, peritoneal cavity filled with yellow foul-smelling fluid.
The authors conclude that because glyphosate and POEA potentiate each others toxicity, it is not reasonable to rely on calculations based on individual toxicities when both ingredients are present in combination. Concentrated glyphosate/POEA combinations pose a very serious hazard to the lung on direct contact.
7. Morrison, Howard I. et al (1992), "Herbicides and Cancer". JOURNAL OF THE NATIONAL CANCER INSTITUTE, v.84 no.24, p.1866-1874.
Studies of herbicides were identified through a MEDLINE search. This review of the literature shows reasonable evidence suggesting that occupational exposure to phenoxy herbicides results in increased risk of developing several kinds of cancer. Although there have been too few appropriate studies for adequate assessment of risk of cancer at other sites, some findings have linked herbicide exposure with cancers of the colon, lung, nose, prostate and ovary as well as to leukemia and multiple myeloma. Future studies must better identify and quantify the nature of herbicide exposures. In the interim it seems only prudent to monitor and promote safety practices among persons occupationally exposed to phenoxy herbicides, particularly farmers and professional sprayers. This review did not include studies of civilian and military persons exposed to herbicides during the Vietnam war, partly because accurate estimation of doses of exposure is problematic.
Tables in the review indicate the design of case-control studies and give type of cancer, location and time of study, the number of cases, the source of controls and the herbicide involved.
An investigation of Swedish railway workers showed a significant excess of stomach cancer among workers exposed to phenoxy acids after a latency period of 10 years. Another Swedish study indicated that a group of workers exposed to 2,4-D experienced a significant excess of deaths from nasal cancer.
Others findings include: significant relationship of risk of death from prostate cancer in farmers to number of acres sprayed; increased risk of testicular cancer among employees manufacturing phenoxy herbicides; increased risk of mesothelial ovarian tumor with herbicidal exposure; increased risk of epithelial ovarian tumors associated with triazine herbicides; risk of brain gliomas associated with agricultural chemicals. The strongest suggestion that herbicides may be human carcinogens come from studies of non-Hodgkin's lymphoma in United States, Australia, and New Zealand, most involving agricultural applications.
More research is needed on latency issues and on exposed female populations. Public education on safety issues is required. A bibliographic list of 65 citations follows the article.
8. Peach, J. Dexter et al (1990), "Lawn care pesticides: risks remain uncertain while prohibited safety claims continue." U.S. General Accounting Office. Report no. GAO/RCED-90-134.
The authors point out that the lawn care pesticides industry continues to make prohibited claims that its products are safe or nontoxic. These claims are prohibited by law because they differ from claims allowed as part of the approved registration. EPA PROHIBITS the following claims for pesticides on the basis that they are false and misleading: 1. any statement directly or indirectly implying that the pesticide is recommended or endorsed by any federal agency; 2. claims such as "safe," "harmless," "nontoxic to humans and pets," with or without a qualifying phrase such as "when used as directed;" 3. non-numerical or comparative statements on the safety of the product, , such as "contains all natural ingredients," among the least toxic chemicals known."
Roundup (glyphosate) and Arsenal (imazapyr) are among the most commonly used lawn care pesticides and are included in those chemicals for which false and misleading claims are still being made by various industries. Even EPA states that no pesticide is safe because pesticides are, by their very nature, designed to be biologically active and kill various kinds of organisms. MIsleading claims also lead users to believe that precautions on pesticide labels can be disregarded.
9. Rank, J. et al (1993), "Genotoxicity testing of the herbicide Round-up and its active ingredient glyphosate isopropylamine using the mouse bone marrow micronucleus test, Salmonella Mutagenicity test, and Allium anaphase-telophase test". MUTATION RESEARCH v.300 (1993) p.29-36. The results of other studies are conflicting and none of them have tested both Roundup and glyphosate in the same assay. This study looks at both and finds that the formulated product Roundup is more toxic than glyphosate itself and can produce point mutations, weak spindle disturbances. Roundup is about 5 times more toxic to Allium root cells than glyphosate. This difference is due to the surfactants, comprising about 15% of the formulation. The authors
point out that "to our knowledge there are no published genotoxicity data on (the) surfactants (in Roundup)".
10. Sittig, Marshall, HANDBOOK OF TOXIC AND HAZARDOUS CHEMICALS AND CARCINOGENS, 3rd edition, v.2 (Park Ridge, NJ: Noyes Publications, 1991), p.959-960. Isopropylamine is a colorless liquid with an ammonia-like odor used in the synthesis of pesticides, surface active agents, and other products. The odor threshold is 5ppm. Effects of inhalation include irritation of the nose, throat and lungs, build-up of fluid in lungs, with possible death resulting. Contact with liquid or vapor can cause severe burns of the eyes and skin, blurred vision.
11. Smoak, Ida W., DVM, PhD (1993), "Embryopathic effects of the oral hypoglycemic agent chlorpropamide in cultured mouse embryos." AMERICAN JOURNAL OF OBSTETRICS AND GYNECOLOGY, 169:409-414.
Chlorpropamide is a first-generation sulfonylurea used to treat non-insulin dependent diabetes mellitus (NIDDM), is rapidly absorbed. This study shows that the drug, whose effect is of long duration, produces malformations and growth retardation in mouse embryos in vitro at concentrations overlapping therapeutic levels in humans. Human studies have shown placental transfer of chlorpropamide and resulting embryopathic effects during early gestation. (This drug is related to the herbicide Oust whose active ingredient is sulfometuron methyl, a sulfonylurea compound.)
12. Smoak, Ida W. (1992), "Teratogenic effects of tolbutamide on early-somite mouse embryos in vitro. DIABETES RESEARCH AND CLINICAL PRACTICE, v.17, pp.161-167.
Tolbutamide is a first generation sulfonylurea used widely in the treatment of NIDDM (see above). This study is the first in-vitro evaluation of the drug using whole-embryo culture in which embryopathic effects were found to be the result of the drug itself and not of hypoglycemia.
13. Temple, Wayne A. and Smith, Nerida A. (1992), "Glyphosate herbicide poisoning experience in New Zealand". NEW ZEALAND MEDICAL JOURNAL, no. 105, (May 13) pp.173-174.
The New Zealand National Poisons Information Centre has summarized the poisoning cases involving glyphosate. The majority of incidents involved accidental exposures, the effects of which responded well to symptomatic and supportive care. In contrast, deliberate ingestions of large amounts of the herbicide resulted in serious toxicity involving gastrointestinal irritation, cardiovascular compromise, pulmonary congestion, renal dysfunction and death in two cases. THERE IS NO SPECIFIC ANTIDOTE (emphasis added); aggressive, supportive management is essential. The range of toxicity includes the following:
Dermal or eye contact produced tachycardia, palpitations, elevated blood pressure, headache, nausea, swollen face, paraesthesia, generalised pompholyx;
Ingestion produced vomiting, and continued nausea;
Fatal ingestions: A 69 year old male patient was in a deeply unconscious and hypotensive state after intentional ingestion, did not respond to supportive measures and died 8 hours later.
A 43 year old female ingested 200-250 ml of Roundup concentrate which made her semiconscious and produced other symptoms such as dilated pupils, hypotension, metabolic acidosis and hyperkalaemia. In spite of intensive care she died in respiratory and cardiac arrest.
The article goes on to discuss remedial measures for mild exposures.
14. Vigfusson, N.V. and Vyse, E.R. (1980), "The effect of the pesticides, Dexon, Captan, and Roundup, on sister-chromatid exchanges in human lymphocytes in vitro". MUTATION RESEARCH, v.79 p.53-57.
Dexon and Captan have both been shown to be potent mutagens, and inducers of sister-chromatid exchanges (SCE). "The EPA has recently triggered Captan for RPAR (rebuttaable presumption against registration) because of its mutagenicity, possible oncogenicity and teratogenicity." (p.56) Roundup has not previously been tested for its effect on DNA. Roundup does produce significant increases in SCE, but in higher concentrations over those used for other pesticides, suggesting that it should be evaluated in other genetic tests measuring mutations and chromosome aberrations.
15. Yousef, M.I. et al (1995), "Toxic effects of carbofuran and glyphosate on semen characteristics in rabbits". JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH, part B. v.30 p.513-534.
This chronic feeding study is important because it tested the effects of doses as low as 1/100th of the LD50 (4260 mg/kg) for rabbits and demonstrated lasting, adverse affects on the reproductive ability of rabbits. (LD50 = the dose necessary to kill 50% of the lab test population.) For the animals fed the pesticides, the overall mean bodyweight of the rabbits was affected significantly. Other observations included: reduced libido, significantly reduced ejaculate volume which did not recover during recovery period; significant reduction in sperm concentration that continued through the 6-week recovery period, drastic increase in sperm abnormalities and dead sperm; decrease of fructose concentration which may contribute to shortening of sperm liveability (fructose represents the main source of energy for spermatozoa). The present study indicated that both low and high doses of glyphosate produced decreases in semen osmolality. The hazardous effects of the two pesticides continued through the recovery period, suggesting a long-lasting effect on sperm formation and other reproductive organs. The LH and FSH hormone secretions and glucose utilization are adversely affected, due either to the cytotoxic effects of the herbicides on spermatogenesis and/or indirectly via the hypothalami-pituitary-testis axis which control the reproductive efficiency.
16. Yusuke Sawada et al (1988), "Probable toxicity of surface-active agent in commercial herbicide containing glyphosate." LANCET, Feb.p.299. This article reports findings on the toxicity of the surfactant POEA, of which the median lethal dose is less than one-third that of roundup and its active ingredient. This class of surfactant has been known to cause gastrointestinal and central nervous system symptoms and haemolysis.
IMPACT OF HERBICIDES ON BIRD POPULATIONS
17. MacKinnon, D.S. and Freedman, B. (1993), "Effects of silvicultural uses of the herbicide glyphosate on breeding birds of regenerating clearcuts in Nova Scotia, Canada." JOURNAL OF APPLIED ECOLOGY, v.30, p.395-406. In this five-year study, the authors admit to controversy over the non-target environmental effects of herbicides and also state that "there have only been a few published studies in North America, and none from Canada, of the effects of silvi-cultural glyphosate use on breeding birds".(p.396) The present study case was near Stewiacke, Nova Scotia. Densities of most common breeding species decreased on all treatment plots, including the reference plot. The White-throated sparrow and the common yellow decreased significantly, as did also the alder flycatcher, especially on the spray plots.
The authors questioned the uses of the spot-map census method in determining the post-spray populations and reproductive success on the sprayed plots. They continue with a discussion of why birds would return to clearcut areas and sprayed areas, and state that "there
might not be notable differences in the density of territories between first-year herbicided and reference clearcuts, but there could be differences in reproductive success.
The second year after herbicide spraying they observed a decreased abundance of some bird species, "which may be related to the herbicide treatment", due possibly to site tenacity even in the face of deteriorated habitat quality. The authors refer to the Santillo study referenced below in the bibliography, and to a study by Savidge (1978) who did a six-year study for a California plantation sprayed with 2,4,5-T; in that study total aviana density decreased to less than half of the reference area. The authors also state that "small islands ...deliberately or accidentally left unsprayed...will generally be too small to allow birds to breed in a similar abundance or with similar success as in unsprayed habitats", and note a "pressing need for information on the longer-term effects of silvicultural herbicide use, especially in the context of the conversion of mixedwood- and hardwood-forested landscapes to conifer-dominated forests".
18. Santillo, D.J. et al (1989), "Response of songbirds to glyphosate-induced habitat changes on clearcuts." JOURNAL OF WILDLIFE MANAGEMENT, v.53 no.1, p.64-71.
This 2-year investigation selected 6 study sites in north-central Maine. Glyphosate was applied by helicopter at a rate of 4.7 L active ingredient/42.1L water/ha. The alder flycatcher and eastern kingbird were not included in the study because of small population. Insectivorous foliage gleaners, primarily common yellowthroats, decreased on the 2 plots treated in 1983 and in 1985. Territories of these birds on treated sites concentrated in areas that had been skipped during the spraying. Total abundance of song-birds was 36% lower on herbicide-treated clearcuts that were vegetationally less complex than untreated clearcuts for at least 3 years post-treatment." (p.69)
Invertebrates were less abundant on treated clearcuts. There were also areas on all treated sites where conifers did not persist, such as within wet swales.
III. TOXICITY OF HERBICIDES TO FISH, AQUATIC INVERTEBRATES AND AMPHIBIANS
19. Austin, A.P. et al (1991), "Impact of an organophosphate herbicide (glyphosate) on periphyton communities developed in experimental streams." BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY v.47, p.29-35.
Glyphosate could potentially act as a phosphorus source and thus could stimulate undesirable eutrophication of waterways, especially those used by salmon or trout. The paucity of published research on the action of glyphosate on aquatic species composition, bioaccummulation, food chain relationships, further recommends caution in the application of this herbicide.
20. Bidwell, J.R. and Gorrie, J.R. (June 1995), "Acute Toxicity of a herbicide to selected frog species: final report." Prepared for Western Australian Dept. of Environmental Protection, Perth, Australia. Studies commissioned by the Department of Environmental Protection in Southwest Australia showed that tadpoles (which respire with gills) were many more times sensitive to the full formulation than adult frogs, and were considerably more sensitive to the formulation (Roundup 360) than to technical grade glyphosate. Some surfactants affect aquatic organisms by damaging the gill membrane. LC50 values for adult frogs indicate there may be very little safety margin between concentrations in shallow water and concentrations lethal to frogs. Frogs are exposed to herbicides through runoff or overspray from treated areas adjacent to permanent or temporary wetlands. These findings are relevant to Vermont because of the endangered status of several amphibian species in Vermont and the prevalence of water and wet areas in our forests.
21. Folmar, L.C. et al (1979), "Toxicity of the herbicide glyphosate and several of its formulations to fish and aquatic invertebrates." ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, v.8 (1979) p.269-278.
8.
In fish exposed to 2.0 mg/L of Roundup the fillets contained 80 mg/kg of glyphosate and the eggs contained 60 ug/kg. Also, significant increases in stream drift of midge larvae was observed after the 2.0 mg/L of Roundup treatment.
The toxicity of Roundup to rainbow trout and bluegill increased with increasing temperature. Roundup was about twice as toxic to rainbow trout at 17 degrees C than at 7 degrees C. It is also more toxic to bluegills at 27 degrees C than at 17 degrees C. Roundup was more toxic to rainbow trout and bluegills at pH7.5 than at pH6.5. Technical glyphosate was less toxic to fish at a higher pH, but the surfactant appeared to be more toxic at the higher pH. Solutions of Roundup aged for up to 7 days in reconstituted water at 12 and 22 degrees C did not change in toxicity to midge larvae, rainbow trout, or bluegills.
Applications of Roundup to ditchbanks near aquatic ecosystems may be hazardous to resident fauna, particularly if the water temperatures are elevated or the pH exceeds 7.5.
22. Goldsborough, L.G. and Brown, D.J. (1988), "Effect of glyphosate (Roundup formulation) on periphytic algal photosynthesis." BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, v.41, p.253-260. The objective of the present study was to assess the effects of the Roundup formulation of glyphosate on short term carbon assimilation by periphytic (growing in fresh water) algal communities collected from six small forest ponds. The 6 study ponds were located in boreal forest near Lake Winnepeg in Manitoba. The short term photosynthetic rates of intact periphyton communities were significantly impacted by glyphosate additions. Glyphosate concentrations less than .89mg/L had no effect on short term algal photosynthesis, while the EC-50 value (glyphosate level resulting in 50% inhibition of carbon fixation) lies between 8.9 and 89mg/L.
23. Servizi, J.A. et al (1987), "Acute toxicity of Garlon 4 and Roundup herbicides to Salmon, Daphnia, and Trout." THE BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY v.39 (1987) p.15-22.
This report summarizes the acute lethality of Garlon 4, Roundup and a surfactant (MON 0818) contained in the formulation of the latter to sockeye salmon, rainbow trout and coho salmon. This study is important because it establishes the evidence that the combined effect of glyphosate and the surfactant POEA is more than additive (synergism). The authors cite the Folmar study (see above in bibliography), noting that the investigators reported a 4.8 fold increase in LC50 (for Roundup) as pH decreased from 7.5 to 6.5.
MON0818 (surfactant) was tested separately from glyphosate and found to be much more toxic than the latter. Further testing showed that the combined effect of glyphosate and MON0818 were "more than additive and raises doubt that the LC50's reported for Roundup in reconstituted water are applicable to natural waters.
24. Wan, M.T. et al (1991), "Acute Toxicity to juvenile pacific northwest salmonids of Basacid Blue NB755 and its mixture with formulated prroducts of 2,4-D, Glyphosate, and triclopyr." BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, v.7, pp.471-478.
Basacid Blue NB755 (BB) is a triphenylmethane dye manufactured by BASF Corporation, New Jersey. This product is used mainly as a marker by aerial and ground herbicide spray operators in forestry. Concerns were raised about the acute toxicity to young salmon of this dye and its mixture with several common herbicides. This bioassay study indicates that basacid blue dye is quite toxic to salmonids. The uses of this dye as an indicator at the rate of 100mg/L in spray mixtures increases the toxicity to young salmon of formulated products of 2,4-D amine, 2,4-D ester, Garlon 4, irrespective of water types. Use of BB with Roundup should not exceed 100mg/L (=8mlBB/100L spray mix), since the impact of this coloring material at greater concentrations has not been evaluated.
IV. IMPACT ON MICROBIAL BIOMASS, FUNGI, FOREST SOILS, AND PLANTS
25. Burnet, Michael and Hodgson, Brian (1991), "Differential effects of the sulfonylurea herbicides chlorsulfuron and sulfometuron methyl on microorganisms." ARCHIVES OF MICROBIOLOGY, 155:521-525.
The authors conclude that the application of sulfonylurea herbicides to soil will cause changes to the existing microbial balances, especially with alkaline soils where chemical degradation is minimal. When the effectiveness of plant pathogens is increased by the inhibition of antagonistic microorganisms by herbicide use, non-target species are more susceptible to disease.
26. Carlisle, S.M. and Trevors, J.T. (1988), "Glyphosate in the environment." WATER, AIR, AND SOIL POLLUTION 39:409-420.
Glyphosate's ability to chelate metal ions may contribute to its toxic effects; calcium uptake by roots grown in solutions containing glyphosate is inhibited. Glyphosate competes with inorganic phosphate for soil binding sites, and appears to bind to cations already adsorbed to the soil; ferric, ferrous, and aluminum ions enhance its binding. The susceptibility of plants to pathogens is increased by glyphosate treatment. The rate of glyphosate degradation correlates with the soil respiration rate, an estimate of microbial activity. Glyphosate has been found to inhibit growth (at 50ppm) of 59% of randomly selected soil bacterial, fungal, actinomycete, and yeast isolates; of nine herbicides tested, glyphosate was the second most toxic.
27. Estok, D. et al (1989), "Effects of the Herbicides 2,4-D, Glyphosate, Hexazinone, and Triclopyr on the growth of three species of ectomycorrhizal fungi." BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY v.42, p.835-839.
The benefits imparted host plants by mycorrhizal fungi are well documented. The most frequently cited benefits are increased nutrient uptake and improved resistance to stress. These symbiotic associations are necessary for the proper growth and development of most vascular plants, including commercially important gymnosperm trees. This study examined the effects of 4 herbicides on three types of ecto-mycorrhizal fungiand found that the herbicides significantly reduced the radial growth of each species of fungus at concentrations of 1000ppm. There is evidence of inhibition of fungal growth at herbicide concentrations greater than 100ppm. It should be noted that agar medium (used in assays) presents a very different condition from that present in the complex and variable environment of the forest floor. Several factors involved in comparing these two environments are discussed.
The estimate of the half-life in soil and the forest floor range from about 2 to 6 weeks for 2,4-D, and 3 to 134 days for glyphosate.
28. Fletcher, J.S. et al (1993), "Potential environmental risks associated with the new sulfonylurea herbicides." ENVIRONMENTAL SCIENCE AND TECHNOLOGY, v.27, p.2250-2252.
The first sulfonylurea herbicide (chlorsulfuron) was introduced in 1982. Members of this herbicide class are known for high toxicity toward plant growth and low application rate. Minute amounts of these herbicides (such as might be found in airborne particles traveling long distances) are capable of disrupting plant reproduction processes, even without visible damage to the plant or its vegetative organs. Drifting sulfonylureas may severely reduce both crop yields and fruit development on native plants, an important component of the habitat and foodweb for wildlife. The danger of widespread environmental damage from this class of herbicides warrants a concerted research effort to gain a clearer understanding of the behavior of this chemicals in the environment.
29. Hendricks, C.W. and Rhodes, A.N. (1992), "Effect of Glyphosate and Nitapyrin on selected bacterial populations in continuous-flow culture." BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY v.49, p.417-424.
Nitrogen is a nutrient in the terrestrial environment which controls the overall productivity under certain conditions, can become limiting to growth. Although the atmosphere provides a nearly endless supply of dinitrogen, most forms of life require nitrogen to be fixed for the synthesis of cellular constituents. Plants can obtain all of their carbon by fixing carbon dioxide, but they are dependent on the availability of inorganic nitrogen and other nutrients present in the soil. Nitrification, the oxidative conversion of ammonium ions to nitrate, produces the principle form of nitrogen assimilated by higher plants, and is under the control of relatively few genera of bacteria.
This study examined the effects of Nitrapyrin and glyphosate, which has a weak potential for affecting nitrification. Based on their known characteristics in routine soil culture, we felt that these two test chemicals would provide an effective and sensitive means to assess the effect of a chemical stressor on an important ecosystem process, nitrification.
Both chemicals tested inhibited nitrifying bacteria in the test soil, but their numbers were not appreciably changed. The sensitivity to nitrification inhibitors, however, varied greatly among the genera of nitrifying bacteria. Nitrosolobus and Nitrosospira were more prevalent than Nitrosomonas among the ammonium oxidizing bacteria present in this soil. Nitrosolobus may be ecologically important due to its greater resistance to chemical inhibitors.
30. Levesque, C.A. and Rahe, J.E. (1992), "Herbicide interactions with fungal root pathogens, with special reference to glyphosate." ANNUAL REVIEW OF PHYTOPATHOLOGY v.30 (1992) p.579-602.
This review documents how herbicides can alter soil ecosystems by having a direct effect on various components of the soil microflora, such as plant pathogens, antagonists, or mycorrhizae. These effects can result in increased or decreased incidence of plant disease, for example through promotion or suppression of the activities of beneficial microorganisms. Nonspecialized pathogens can increase their inoculum potential on weeds and subsequently affect crops. As still another effect, herbicides can predispose pathogens to fungicides or act as synergists.
Detection of herbicide residues in plants and soil is difficult. Glyphosate is readily adsorbed to soil particles by electrostatic force and hydrogen bonding, and it also forms insoluble metal complexes. Adsorption of glyphosate to soil particles is positively correlated with clay content and generally decreases as pH decreases. Glyphosate can be degraded by various microorganisms and by ultraviolet light. After one year residue concentration (in western Canada) was 6-18% of that seen immediately after spraying, and almost all the residues were in the top 15 cm of soil. Herbicide-induced weakening of the crop plant can pre-dispose the plant to infection by pathogens. The herbicide, even at sublethal doses, blocks the synthesis of phenolics that are involved in resistance of plants to diseases. Young apple trees have been adversely affected by accidental exposure to glyphosate. Other crops negatively affected include bean, soybean, asparagus, flax, tomato.
The negative effect of atrazine on the fungus C. sativus was increased by lowering soil pH or increasing humic acid content.
The efficacy of herbicides in forestry varies considerably for reasons that are still not clear. No long-term studies have been done in Canada on the effect of herbicides on forest vegetation. Depending on locations, site preparation with glyphosate had either a positive or no effect on the survival of conifer seedlings compared to unsprayed controls (Oskarsson et al 1990).
31. Maciorowski, A.F., United States Environmental Protection Agency (1994) "Memorandum: Qualitative Assessment of sulfonylurea herbicides and other ALS inhibitors."
From a chronology of Ecological Effects Branch (EEB) involvement with sulfonylurea (SU) herbicides, the following comments were indicative of concerns. "Most SU nontarget plant phytotoxicity data reviews for low dosage herbicides and volatile herbicides since 1988 have resulted in the recommendation to the Registration Division that aerial applications not be allowed. (p.2) In 1992, "At 1/100th the maximum label application rates, the SU's were significantly more phytotoxic to roses than the other herbicides tested.(p.4)" "...analytical methodology is not currently available to detect SU's in environmmental samples at the levels that cause adverse effects on plant growth...The 'weight of evidence ... leads the EEB to offer (these) recommendations: delete aerial applications from all ALS inhibiting herbicide labels; issue a moratorium on the further registration of ALS inhibiting herbicides until residue detection methods are commonly available that can detect residues at levels in soil, water, air, and plant samples that are phytotoxic to plants; initiate research... using plant life-cycle studies...." (p.9-10)
32. Piccolo, A. et al (1994), "Adsorption and desorption of glyphosate in some European soils." JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH, part B, v.29, pp.1105-1115.
This study was significant for its findings that glyphosate adsorption on soils is far from being permanent, and leaching to lower soil levels with limited biological activity can occur.
33. Saari, L.L. (1992), "Sulfonylurea herbicide resistance in common chickweed, perennial ryegrass, and Russian thistle." PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY, v.42, pp.110-118.
Sulfonylurea herbicide resistance was demonstrated in two broadleaf species in greenhouse tests. The resistance in each of the three weed biotypes was due to an acetolactate synthase (ALS) enzyme that was less sensitive to inhibition by ALS-inhibiting herbicides.
34. Sidhu, S.S. and Chakravarty, P. (1990), "Effect of selected forestry herbicides on ectomycorrhizal development and seedling growth of lodgepole pine and white spruce under controlled and field environment." EUROPEAN JOURNAL OF FOREST PATHOLOGY, v.20 p.77-94.
Sidhu et al observed that in general, seedlings inoculated with mycorrhizal fungus were more sensitive to herbicide that the ones without mycorrhizal inoculation. In non-herbicide treatments, growth and number of short roots per seedling were greater in seedlings inoculated with the mycorrhizal fungus S. tomentosus (S.t.). The mycorrhizal infections of the short roots and other growth parameters were significantly reduced from controls in all concentrations of the three herbicides tested.
35. Sprankle, Paul et al (1975), "Adsorption, mobility, and microbial degradation of glyphosate in the soil." WEED SCIENCE 23:3:229-234. In this study quartz sand was used as the control and compared to various clay soils. Wheat plants were grown in the sand and clay soils to be an indicator of herbicide activity. There was a slower rate of degradation in Toledo clay loam soil, possibly due to fewer microorganisms present, or to tenacity of glyphosate binding. The pattern of glyphosate degradation suggests that glyphosate did not support microbial growth. The cation-saturated clays showed great differences in the adsorption of glyphosate. Fe+++ and Al+++-saturated clays and organic matter adsorbed more glyphosate than Na+ or Ca+-saturated clays and organic matter.
36. Wigfield, Y.Y. et al (1994), "Residues of glyphosate and its principle metabolite in certain cereals, oilseeds, and pulses grown in Canada, 1990-1992." BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, 53:543-547.
This author found that use of glyphosate as Roundup or Vision near harvest time can result in high levels of residues throughout the whole plant including the seed coat. A major metabolite of glyphosate, aminomethylphosphonic acid (AMPA) was detected at lower levels in some samples. This is significant in view of the proposed use of this herbicide in August or early September, when humans and animals are harvesting berries, herbs, and other plant materials in or near treated areas.
V. FOREST MANAGEMENT ISSUES
37. Acksell, Lennart (1994), "Natural regeneration on planted clear-cuts in boreal Sweden." SCANDINAVIAN JOURNAL OF FOREST RESEARCH, v.9, pp245-250. Logging methods and site factors are considered in this 10-year study of natural regeneration on a clearcut in Sweden. Nearby seed sources (seed-producing stands within 100 meters) were associated with more seedlings of all species, but more important for conifers than for deciduous, which occurred mostly on eastern slopes and in wet locations. Deciduous seedlings may provide protection for conifer seedlings on harsh sites after clearcutting, up to about 15 years. The author concluded that forest management that includes natural forces in a combined regenerative strategy might gain in wood productivity, economic return, wood quality and also in nature conservatory aspects, and that a study longer than 10 years is needed for more definitive conclusions.
38. Freedman, Bill (1991), "Controversy over the use of herbicides in forestry, with particular reference to glyphosate usage." JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH v.8 part C , pp.277-286.
Some disadvantages to the silvicultural uses of herbicides are 1. the possibility that competing vegetation may not be adequately controlled, or conifers may be damaged; 2. nontarget, off-site damage may be caused by drift of herbicide spray; 3. fewer people are employed in vegetation management programs; 4. weed control, by any method, may interfere with useful ecological functions of competing vegetation, for example an ability to take up essential nutrients and thereby prevent their leaching from the disturbed site, or serving as a component of the habitat of various species of early successional wildlife; and 5. there is often a highly vocal, strongly negative, social reaction to the broadcast spraying of pesticides in forestry.
Factors that increase off-target drift from either aerial or ground sprays include: 1. excessive winds i.e. greater than ca10 km/hr; 2. the use of sprays with a large proportion of fine droplets with a correspondingly small deposition rate 3. calm conditions, in which spray is not driven onto plant foliage by turbulent air. Various measurements of on-target deposition include: (Nova Scotia) 18-59% from helicopter treatments; 22-86% from 3 ground sprays. Inefficient on-target deposition can result in damage to off-target vegetation, inadequate control of competing vegetation, exposure of off-site wildlife and humans to the herbicide. The toxicity of glyphosate to aquatic biota is less than that of its various formulations. Glyphosate causes great habitat changes in its effects on plant productivity and by changing the distribution of biomass in 3-dimensional space and among plant species. The measuring of bird populations is problematic on herbicided clearcuts; there are not any studies of the reproductive success of birds breeding on recently treated clearcuts.
In Alberta, Canada, the silvicultural uses of glyphosate in aerial applications has been proscribed.
Freedman points out various forest management concerns, i.e. monoculture vs biodiversity, changes in landscape character vis a vis vegetation and wildlife habitat, incompatibililty of intensive harvesting with multiple land use.
39. Hjeljord, Olaf and Gronvold, Sven (1988), "Glyphosate application in forest ecological aspects. IV. Browsing by moose in relation to chemical and mechanical brush control." SCANDINAVIAN JOURNAL OF FOREST RESEARCH. 3:115-121.
This study in southern Norway examined effects of glyphosate and mechanical contol after two growth seasons on browse production in forest plantations, as well as the ability of moose to restrict growth and development of hardwoods. Mechanical cutting was found to be far more favorable to browse production than spraying with glyphosaste. The most important browse species S. Aucuparia (rowan) has greater difficulties reestablishing on clearcuts after spraying. Seeds of S. Aucuparia seeds are spread by birds, whereas birch seeds are spread by wind. Birch is a higher portion of moose diet in summer than in winter. Browsing by moose was found to relieve the spruce seedlings on the clearcuts from considerable competition by hardwoods and alters the composition of the hardwoods to mostly common birch.
40. Miles, Carl J. et al (1986), "Determination of glyphosate herbicide and aminomethyl phosphonic acid in natural waters by liquid chromatography using pre-column fluorogenic labeling with 9-fluorenylmethyl chloroformate." JOURNAL OF THE ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS
69:458-461.
The effect of glyphosate on non-target organisms and its overall environmental fate cannot be fully evaluated unless techniques possessing suitable sensitivity and selectivity are available. The ionic, water-soluble character of glyphosate and AMPA (its major metabolite) make analysis by liquid chromatography (LC) advantageous. Of two fluorescence detectors evaluated, the spectrophotofluorometric (SPF) instrument was 20-50 times more sensitive. In experiments where glyphosate was fortified into a natural water and frozen at 0 degrees C for 3 months, it was not significantly degraded. (This observation has significance for evaluation of this herbicide in cold climates.)
41. Newton, Michael et al (1984), "Fate of glyphosate in an Oregon forest ecosystem." JOURNAL OF AGRICULTURE AND FOOD CHEMISTRY 32:1144-1151. Glyphosate residues and metabolites were evaluated in forest brush field in Oregon coast range. Concentrations were higher in sediment than in water and persisted longer. Early stream-bottom samples reflected concentratrions found in the streamwater, but later samples showed that even the water concentrations occurring below the detection limit may contain enough glyphosate to contribute to adsorption by sediments. Of particular interest was the author's finding that residues (of glyphosate) in animals may remain detectable for several months. Concentrations in viscera were always higher than those in the remainder of the animal.
42. Payne, Gary (1988), "Pesticide residues in wildlife: violating legal standards?" JOURNAL OF PESTICIDE REFORM, 7:4:18-19.
This article discusses the amounts of pesticides in wild plants and animals consumed by humans, and relates the presence of these residues to EPA standards for residue levels in domestic foods. The amounts of glyphosate found in the animals in the Newton study (see above) violated legal standards for human edibility. Hunting seasons often coincide with spray seasons, especially when glyphosate and its formulations are used. Residues of glyphosate are stable when frozen; the life of the residues are extended indefinitely in frozen food. Berries in sprayed areas have carried 2,4-D loads up to 40 times EPA's legal tolerances. Per-acre application rates in forestry are commonly double those used in agriculture, and agricultural crops are theoretically protected from high residues by use restrictions.
VI. WATER ISSUES
43. Bowmer, Kathleen H. (1982), "Adsorption characteristics of seston in irrigation water: implications for the use of aquatic herbicides." AUSTRALIAN JOURNAL OF MARINE FRESHWATER RESEARCH, 33:443-458. Since phosphate and glyphosate compete for adsorption sites, one implication is that some of the adsorbed glyphosate might be released and the hazard to non-target organisms increased, if phosphate levels in the water were to rise. Effects on glyphosate concentration may be masked by other chemical and hydrological factors influencing glyphosate concentrations downstream from spray zone. Glyphosate adsorption by seston is extremely high compared with adsorption by soils. Adsorption can complex the chemical so that it can move into the aquatic environment by erosion; it can change the availability of the compound to aquatic organisms, and it can alter the rate of biological and chemical degradation. Persistence may increase when adsorption protects chemicals from volatilization and from degradation processes occurring primarily in solution.
44. Smith, N.J. et al (1996), "Levels of the herbicide glyphosate in well water." BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY , v.57,
pp.759-765.
In this study of herbicide use near electrical substations in Newfoundland, Smith et al found that glyphosate (2% solution) did reach a water well at detectable levels over a period of 32 weeks after the area was sprayed with the herbicide. (This is a much more diluted solution than the 41.5% formulation proposed for Vermont.)
45. VERMONT STATUTES ANNOTATED: citations regarding Vermont's Waters V.S.A. sec. 401 (Public Trust doctrine on Vermont's Waters) "Lakes and ponds which are public waters of Vermont and the lands lying thereunder are a public trust and it is the policy of the state that these waters and lands shall be managed to serve the public good."
10 V.S.A. sec.902 definition of Waters:
"Waters" means any and all rivers, streams, brooks, creeks, lakes, ponds or stored water, and groundwaters, excluding municipal and farm water supplies;
"Water resources" means the waters and the values inherent or potential in waters and their uses.
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