Recently an agricultural services firm was retained to spray the herbicide Milestone VM on nearby pastures to kill clover and other broadleaf plants. After spraying, rains washed some of the herbicide downhill from the pastures into the ponds below. Before the spraying, the ponds were full of tadpoles. A few days after spraying, there were no tadpoles in the ponds examined.

Because none of the tadpoles had legs before the spraying, they could not have developed into adult frogs and walked off. Nor could any predator have managed to get every single one of them. And a “control group” — waterways not affected by pasture runoff — still had the tadpoles they had before this spraying. Adult frogs may have been killed as well – the evenings at the ponds after spraying were much quieter than just prior to the spraying.

We could suspect that pasture runoff of Milestone VM into our ponds is the culprit. A literature search confirms this hypothesis (see below).

Studies have shown that herbicides and pesticides may have both direct and indirect effects on tadpoles:

  • Very, very low concentrations of pesticides and herbicides have been found to be a major factor in high levels of deformities in frogs and tadpoles1, and studies have shown that herbicides such as Roundup cause DNA damage in tadpoles.2
  • Very low concentrations may kill tadpoles and frogs in just one day.3
  • Those that are not killed outright by herbicides may die of delayed effects. Malathion, for instance, in very low doses destroys zooplankton that eat algae that floats in the water. With the zooplankton gone, the algae grew rapidly and prevented sunlight from reaching the algae at the bottom of the pond, which tadpoles eat. Some tadpoles then starve to death.4
  • Tadpoles that do not starve will mature slowly, or grow so slowly that they may not reach maturity.5
  • If tadpoles reach maturity, and become adult frogs, herbicides may weaken their immune systems, leaving them susceptible to chytrid fungus infections.6

The known dangers of herbicides for frogs and toads is acknowledged by the National Park Service which, for Yosemite National Park, required that “Herbicides will not be applied within 750 meters (2,500 feet) of known breeding habitat for the Yosemite toad.7

Where pasture runoff flows into streams, ponds, or even ditches, the use of herbicide or pesticide in our pastures should be suspended until the dangers of any proposed substance can be carefully evaluated.

Herbicides that are known to be toxic to wildlife include Milestone VM, Roundup, Powerline and Arsenal, and Tordon K. It seems likely that all herbicides are toxic to wildlife.

Milestone VM

Milestone VM contains the active ingredient aminopyralid.

Aminopyralid dissolves very easily and is persistent in water. It has high leachability and mobility. It is toxic to algae, oysters, aquatic plants8, fish, honeybees and earthworms9.Aminopyralid is also on PAN International’s List of Highly Hazardous Pesticides10.

Recently aminopyralid was at the center of public and media attention in the United Kingdom. Gardeners discovered that using manure from animals that grazed on or were fed hay from aminopyralid-sprayed roadsides caused their garden crops to fail or develop abnormally. In fact, the University of Minnesota Extension Service describes this problem in their fact sheet, “Use Caution When Harvesting and Feeding Ditch Hay.”11

Aminopyralid is of concern to vegetable growers as it can enter the food chain via manure which contains long lasting residues of the herbicide. It affects potatoes, tomatoes and beans, causing deformed plants, and poor or non-existent yields. Problems with manure contaminated with Aminopyralid residue surfaced in the UK in June and July 2008, and at the end of July 2008 Dow AgroSciences (the manufacturer of Milestone) implemented an immediate suspension of UK sales and use of herbicides containing Aminopyralid. A company statement explained: “Consistent with its long-standing commitments to product stewardship, and in cooperation with United Kingdom regulators, Dow AgroSciences has asked the Pesticide Safety Directorate (PSD) for a temporary suspension of sales and use of herbicides containing aminopyralid. The suspension shall remain in place until assurances can be given that the product and subsequent treated forage and resultant animal wastes will be handled correctly.”12

If it is unsafe to eat vegetables raised with manure from pastures treated with Milestone, how safe can it be to eat plants that themselves have been treated with Milestone? Are the horses in treated pastures safe?

Of concern to all is the 2005 claim by the EPA that “There are no acute or chronic risks to non-target endangered or non-endangered fish, birds, wild mammals, terrestrial and aquatic invertebrates, algae or aquatic plants”13, despite the fact that the EPA report cites studies such as “Acute Toxicity to Larval Amphibians Using the Northern Leopard Frog, Rana pipiens, as a Biological Model.”

Even if Milestone/aminopyralid were safe for tadpoles, it would only be when applied at recommended doses to non-sloping land. The recommended dose is just 7 fluid ounces per acre, according to the EPA.14

Roundup

Other commonly used herbicides also put wildlife at risk. Roundup, for instance, kills birds, fish, tadpoles, bees, worms – at least 76 different species.

Roundup contains glyphosate as its active ingredient. Glyphosate dissolves readily and is very persistent in water. It is toxic to birds, fish, honeybees and earthworms15and is listed by PAN International as a highly hazardous pesticide16. Its maker, Monsanto, was convicted of false advertising in 2007 for its claim that Roundup was “practically non-toxic” to mammals, birds, and fish.17 Some of the scientific evidence for the safety of Roundup comes from studies with falsified results.18

The U.S. Environmental Protection Agency (EPA) has identified 76 species that may be endangered by glyphosate use19.An important study has shown that glyphosate kills tadpoles20. A University of Pittsburgh biologist has found that the herbicide caused an 86-percent decline in the total population of tadpoles.21A recent study found that even at concentrations one-third of the maximum concentrations expected in nature, Roundup still killed up to 71 percent of tadpoles raised in outdoor tanks.22

Out of concern for these issues as well as human health, European Union member states are warned that they “must pay particular attention to the protection of the groundwater in vulnerable areas, in particular with respect to non-crop uses,” when using glyphosate23.According to EPA, short-term exposure to elevated levels of glyphosate may cause lung congestion and increased breathing rates and, in long-term exposure, kidney damage, reproductive effects24. Glyphosate has also been associated with Parkinson’s disease.25Increased adverse neurologic and neurobehavioral effects have been found in children of applicators of glyphosate26.Female partners of workers who apply glyphosate are at higher risk of spontaneous abortion27.Some glyphosate-based formulations and metabolic products have been found to cause the death of human embryonic, placental, and umbilical cells in vitro even at low concentrations. The effects are not proportional to glyphosate concentrations but dependent on the nature of the adjuvants used in the formulation.28

Powerline and Arsenal

Powerline and Arsenal contain the active ingredient imazapyr, which has been listed for withdrawal from the market in the European Union.29It is highly soluble and moderately persistent in water. It is also toxic to fish, honey bees and earthworms30. Imazapyr’s potential to leach to groundwater is high and surface runoff potential is high31.One field study found that between 40 and 70 percent of applied imazapyr leached down to the lowest depth tested32. If imazapyr leaches down below 18 inches (where microbial activity is limited) the chemical can be expected to persist for more than a year33.EPA cautions that imazapyr-based herbicides can place terrestrial and aquatic plant species in “jeopardy.”34

Tordon K

Tordon K has the active ingredient picloram. Picloram is a persistent herbicide that is highly leachable, very soluble in water and does not degrade readily in water. It is toxic to birds, fish, honeybees and earthworms. It has also been identified as an endocrine disruptor3536and is on PAN International’s List of Highly Hazardous Pesticides37.EPA’s evaluation of picloram states, “eventual contamination of groundwater is virtually certain in areas where residues persist in the overlying soil. Once in groundwater, the chemical is unlikely to degrade even over a period of several years.”38

Anyone who would advocate against herbicides will face the might of organized agriculture, the lawn care business, and even the EPA. A paper on the Environmental Safety of Forestry Herbicides39, for instance, argues that the herbicides named in the present article – imazypyr, glyphosate, and picloram, as well as many others – are “less toxic than caffeine”, “less toxic than aspirin” and “are safe for animals because the biochemical basis for toxicity does not exist.” The article goes on to claim “herbicides positively affect water quality by reducing sedimentation rates.”

I’d like to think that we could send herbicides to the last roundup. But it seems more likely that herbicides will continue to send wildlife to that roundup.

End Notes

1 Fellers G, Sparling D; Wafting Pesticides taint far-flung frogs, Environmental Toxicology and Chemistry, 2001; Science News, Dec 16,2000, Vol 158, p391; Science News, 9-5-98,p150.

2 http://www3.interscience.wiley.com/journal/10009203/abstract?CRETRY=1&SRETRY=0

3 Even Small Doses of Popular Weed Killer Fatal to Frogs, Scientist Finds http://www.sciencedaily.com/releases/2005/08/050804053212.htm

4 Even Small Doses of Popular Weed Killer Fatal to Frogs, Scientist Finds http://www.sciencedaily.com/releases/2005/08/050804053212.htm

6 http://www.chronicle.pitt.edu/?p=660

7 http://www.nps.gov/yose/parkmgmt/upload/ipmp-fonsi.pdf

8 http://www.epa.gov/opprd001/factsheets/aminopyralid.pdf

9 Pesticide Properties DataBase http://sitem.herts.ac.uk/aeru/footprint/en/index.htm

10 PAN International List of Highly Hazardous Pesticides, 2009. http://www.pan-germany.org/download/PAN_HHP-List_090116.pdf

11 University of Minnosota Extension Service, “Use Caution When Harvesting and Feeding Ditch Hay.” http://www.extension.umn.edu/distribution/livestocksystems/components/M1197.pdf

12 http://en.wikipedia.org/wiki/Aminopyralid. See also http://www.dowagro.com/uk/aminopyralidsuspension.htm

13 http://www.epa.gov/opprd001/factsheets/aminopyralid.pdf

14 http://www.epa.gov/opprd001/factsheets/aminopyralid.pdf

15 Pesticide Properties DataBase http://sitem.herts.ac.uk/aeru/footprint/en/index.htm

16 PAN International List of Highly Hazardous Pesticides, 2009. http://www.pan-germany.org/download/PAN_HHP-List_090116.pdf

17 http://www.organicconsumers.org/articles/article_4114.cfm

18 On two occasions the United States Environmental Protection Agency has caught scientists deliberately falsifying test results at research laboratories hired by Monsanto to study glyphosate. [(US EPA Communications and Public Affairs 1991 "Note to correspondents" Washington DC Mar 1)] [(US EPA Communications and Public Affairs 1991 Press Advisory. "EPA lists crops associated with pesticides for which residue and environmental fate studies were allegedly manipulated". Washington DC Mar 29)] [(U.S. Congress. House of Representatives. Com. on Gov. Oper. 1984. "Problems palgue the EPA pesticide registration activities". House Report 98-1147)] In the first incident involving Industrial Biotest Laboratories, an EPA reviewer stated after finding “routine falsification of data” that it was “hard to believe the scientific integrity of the studies when they said they took specimens of the uterus from male rabbits”. [(U.S. EPA 1978 Data validation. Memo from K LOcke, Toxicology Branch, to R Taylor, Registration Branch. Washington DC Aug 9)] [(U.S. EPA Office of pesticides and Toxic Substances 1983, "Summary of the IBT review program". Washington D.C. July)] [Schneider, K. 1983. Faking it: The case against Industrial Bio-Test Laboratories. The Amicus Journal (Spring):14-26. Reproduced at [http://planetwaves.net/contents/faking_it.html Planetwaves] ] In the second incident of falsifying test results in 1991, the owner of the lab (Craven Labs), and three employees were indicted on 20 felony counts, the owner was sentenced to 5 years in prison and fined 50,000 dollars, the lab was fined 15.5 million dollars and ordered to pay 3.7 million in restitution. [(US Dept. of Justice. United States Attorney. Western District of Texas 1992. "Texas laboratory, its president, 3 employees indicted on 20 felony counts in connection with pesticide testing". Austin TX Sept 29) ] [(US EPA Communications, Education, And Public Affairs 1994 Press Advisory. "Craven Laboratories, owner, and 14 employees sentenced for falsifying pesticide tests". Washington DC Mar 4)] [http://www.mindfully.org/Pesticide/Roundup-Glyphosate-Factsheet-Cox.htm Glyphosate Factsheet (part 1 of 2) Caroline Cox / Journal of Pesticide Reform v.108, n.3 Fall98 rev.Oct00 ] ] Craven laboratories performed studies for 262 pesticide companies including Monsanto. — http://dic.academic.ru/dic.nsf/enwiki/56554

19 U.S. Department of Agriculture, Forest Service, 1997. Herbicide Information Profile: Glyphosate

20 Hileman, B. (2005) Common herbicide kills tadpoles. Chemical & Engineering News. Washington 83(15):11

21 http://www.motherearthnews.com/Organic-Gardening/2005-10-01/Hazards-of-the-Worlds-Most-Common-Herbicide.aspx

22 Even Small Doses of Popular Weed Killer Fatal to Frogs, Scientist Findshttp://www.sciencedaily.com/releases/2005/08/050804053212.htm

23 European Commission, Health & Consumer Protection Directorate-General. Directorate E – Food Safety: plant health, animal health and welfare, international questions. E1 – Plant health. Glyphosate. 6511/VI/99-final. 21 January 2002.

24 http://www.epa.gov/ogwdw/contaminants/dw_contamfs/glyphosa.html (accessed 16 May 2009)

25 Barbosa et al., 2001. Parkinsonism after glycine-derivative exposure. Mov. Disorder. 16: 565-568.

26 Garry et al., 2002. Birth defects, season of conception and sex of children born to pesticide applicators living in the Red River Valley of Minnesota, USA. Environ. Health Perspect. 110: 441-449.

27 Arbuckle et al., 2001. An exploratory analysis of the effect of pesticide exposure on spontaneous abortion in Ontario farm population. Environ. Health Persp. 109: 851-857.

28 Benachour Nora; Gilles- Eric Séralini (December 23, 2008). “Glyphosate Formulations Induce Apoptosis and Necrosis in Human Umbilical, Embryonic, and Placental Cells”. Chemical Research in Toxicology 22: 97. doi:10.1021/tx800218n. http://pubs.acs.org/doi/abs/10.1021/tx800218n].

29 “Pesticides coming off EU market. Pesticide News No. 60, June 2003, pp. 8-10.

30 Pesticide Properties DataBase http://sitem.herts.ac.uk/aeru/footprint/en/Reports/393.htm

31 Washington State Department of Transportation. Imazapyr – Roadside Vegetation Management. Herbicide Fact Sheet. February 2006.

32 Vizantinopoulos, S. and P. Lolos. 1994. Persistence and leaching of the herbicide imazapyr in soil. Bull. Environ. Cont. Toxicol. 52:404-410.

33 “Ecological Risk Assessment of the Proposed Use of the Herbicide Imazapyr to Control Invasive Cordgrass (Spartina spp.) in Estuarine Habitat ofWashington State.” Department of Agriculture, Olympia, WA 98504. Prepared by ENTRIX Inc., Olympia, Washington. Project No. 3000901, October 30, 2003.

34 USEPA. Office of Pesticide Programs. 1987. EEB Review of 241-EEO. Washington, DC (April 21 & June 1)

35 Endocrine disruptors interfere with the endocrine glands that produce hormones that guide the development, growth and reproduction in people and animals. Disruption of hormones, which guide growth, development, intelligence, and reproduction, can result in irreversible harm, which is passed on to future generations.

36 Pesticide Properties Database http://sitem.herts.ac.uk/aeru/footprint/en/index.htm

37 PAN International List of Highly Hazardous Pesticides, 2009. http://www.pan-germany.org/download/PAN_HHP-List_090116.pdf

38 U.S. EPA. Prevention, Pesticides, and Toxic Substances. 1995. Reregistration eligibility decision (RED): Picloram. Washington, D.C., Aug.

39McNabb, Ken. Environmental Safety of Forestry Herbicides http://www.aces.edu/pubs/docs/A/ANR-0846/