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Children play in Pineview Park

Children play in Pineview Park in June 2010. Playground areas in Missoula parks are not sprayed with herbicide.

An herbicide cousin of Roundup is being sprayed to kill weeds in public parks, trails and athletic fields in Missoula.

The Parks and Recreation Department applied nearly 120 pounds of herbicides diluted in more than 550 gallons of water throughout the city of Missoula in 2012, according to pesticide application records from the city. In 2013, Parks and Rec estimates it will spend $8,500 on multiple products.

Herbicides are the last line of defense and also first line of attack against invasive weeds for Parks and Rec, said Donna Gaukler, director. She said the chemicals are just one of many tools in a comprehensive program to keep Missoula’s parks clear of weeds, and turf green and smooth for athletes.

“We try to manage facilities in a sustainable way with a given budget, with safety always in our decision-making process to get the most desired effects,” Gaukler said.

In the early 1990s, the city of Missoula pulled away from the use of herbicides, she said. Since around 2000, though, the products have been an integral part of the strategy to manage public parks and trails here, even as a growing body of science suggests pesticides are damaging to the health of vulnerable populations, children in particular.

Just last year, a report from the American Academy of Pediatrics urged policymakers to take action against pesticides because of their links to childhood cancers and other disabilities and disorders. In light of mounting concerns, communities across the country are declaring some city parks to be free of pesticides.

Alexandra Scranton, lead scientist for Women’s Voices for the Earth, said the chemicals in use in Missoula are not considered “bad actors,” or known carcinogens. However, she said, two active ingredients, isoxaben and pendimethalin, are possible carcinogens, and the latter is a suspected endocrine disruptor.

“All herbicides are going to pose some sort of risk,” Scranton said. “They’re designed to kill things.”


Herbicides are one class of pesticide, and Missoula Parks and Recreation uses them as part of its program to combat weeds.

Parks and Rec uses herbicides as a last line of defense against weeds that are thriving despite larger efforts to curb invasive plants and cultivate desired greenery through mowing and irrigating, Gaukler said. She said the city also uses herbicides as a prevention measure against weeds when it’s developing a park.

“If I can start with a reduced or relatively weed-free zone and plant the desired (grasses and plants) and bring them up to a healthy condition, they will prevent the weeds from coming,” Gaukler said.

Turf is the only place where the city conducts broadcast applications, she said, and she stressed Parks and Rec first uses other methods of weed control. According to application records, the department used the following products in 2012:

  • Glystar Plus, by Albaugh Inc.
  • Dimension 2EW, by Dow Agro Sciences.
  • Mad Dog Plus, by Loveland Products.
  • Pendulum Acqua CAP, by BASF.
  • Gallery 75 Dry Flowable, by Dow Agro Sciences.
  • Curtail, by Dow Agro Sciences.
  • Garlon 4, by Dow Agro Sciences.

A couple of factors led the city to reinstate the use of herbicides, Gaukler said. For one thing, an opinion poll in the late 1990s showed public sentiment had shifted and become more tolerant of herbicides.

“The other thing that happened over those 15 years is some of our (sports) fields became largely unplayable,” Gaukler said.

So athletic groups drove the push to clear the fields, which had become infested with weeds, she said. Dandelions in particular impede play: They obscure the view of a softball in the field and make it hard to pick the ball up, and they leave a slippery substance that creates a hazard for players.

“Can you imagine running to kick a ball in soccer and landing on a big dandelion plant?” Gaukler said. “So it actually became a safety issue for us, and our sports groups were literally clamoring for Parks to please do something.”


In 2012, Parks and Rec applied herbicides in a variety of locations, among them Caras Park, Greenough Park, the Milwaukee Trail, medians on East Pine Street and Splash Montana, according to application records. The city doesn’t use the herbicides on playgrounds, Gaukler said.

“Kids are there all the time, and so we just avoid those areas because you want herbicides to be dry before it’s safe,” she said.

At Splash Montana, a crew member with a backpack sprayer spot-treated the landscaped beds, according to one application record. In a park such as Sacajawea, Parks and Rec does not spray the children’s playground, but it does spray park equipment, curbs and gutters, and tree wells.

Protecting children and managing the land is a balancing act, Gaukler said. For instance, dandelions attract stinging insects, and Parks and Rec hears many concerns from adults about small children getting stung by bees and wasps.

So crews spray, but only if necessary, and only under tightly controlled conditions, she said: “If you’re applying the herbicide when it’s not right for killing the plant, you’re wasting your money, so why do it?”

An important part of the program also is public notification, said Parks and Rec spokeswoman Becky Goodrich. She said people have varying degrees of comfort with the use of herbicides; the city alerts the public so those who want to avoid sprayed areas can do so.

“That’s a huge part of herbicide application, is letting people know,” Goodrich said.

According to an overview from Parks and Rec, the public notification procedure is this: “The department exceeds legal requirements by posting areas to be treated 24 hours before application and 24 hours after application. Multiple signs are used to mark treated areas.”


The active ingredient in a couple of products used in Missoula is glyphosate, and it’s also the active ingredient in Roundup.

“It is often said that ‘there is no indication of any human health concern’ for glyphosate,” reads an herbicide factsheet published by the Northwest Coalition for Alternatives to Pesticides. “However, this herbicide can actually pose significant hazards to human and environmental health.”

Studies offer a variety of conclusions, and the discrepancies are due to multiple factors. For starters, products often are approved before research has shown them to have toxic effects, and an effort is underway on the national level to require more data before putting chemicals on the market, said Scranton, with Women’s Voices for the Earth.

Jane Hoppin, an environmental epidemiologist, has been studying the effects of glyphosate and pendimethalin since 1993, and she said it doesn’t have a lot of “acute human toxicity.” Hoppin, with the National Institutes of Environmental Health Sciences, is a lead scientist on an agricultural health study of 60,000 farmers and families in North Carolina and Iowa.

One model comparing the rates of cancer among farmers in the study to the general population found no evidence that exposure to pesticides increased risk, she said. It suggested a link to multiple myeloma, but didn’t confirm it; it didn’t include breast cancer since that occurs more in women.

“For overall cancer risk, there was no difference from the general population, and there’s no difference based on how much pesticides they were using,” Hoppin said.

The study doesn’t offer conclusions for every population, however. For one thing, Hoppin said, it’s a study of farmers, mostly men, and mostly strong adults who are generally pretty healthy compared to the general population, given their line of work.

The enrollment age was 47, so the study doesn’t offer information about how exposure affects pregnant women or its potential to cause birth defects, she said. The study isn’t designed to analyze the effect of the chemicals on children, either.

“So we don’t know vulnerable populations,” Hoppin said.


Other studies offer different conclusions, according to an overview of the research from the Northwest Coalition for Alternatives to Pesticides. Based in Eugene, Ore., NCAP works to protect environmental health and advance the use of “ecologically sound solutions to reduce the use of pesticides.”

Here are some findings reported in the overview, which includes citations to journal articles and is posted online with this story. It notes some studies of glyphosate herbicides cover only glyphosate itself; others cover glyphosate and “inert” ingredients which also have been found to be dangerous, according to the review.

Genetic damage:

  •  “Four laboratory studies published in the late 1990s demonstrated the ability of glyphosate and glyphosate-containing herbicide products to cause genetic damage.” One study in Italy on human blood cells showed “glyphosate caused a significant increase in the number of abnormal chromosomes.”
  • “The National Institute for Occupational Safety and Health describes glyphosate as a mutagen.”


  • “A 2001 study of Canadian men (by the University of Saskatchewan) showed that the risk of non-Hodgkin’s lymphoma for men exposed to glyphosate more than two days per year was two times greater than the risk for men who were either unexposed or exposed for less than two days per year.”
  • “Researchers at the University of Minnesota found that both glyphosate and Roundup caused a rapid increase in cell division in human breast cancer cells.”

Effects on pregnancy:

  • Glyphosate exposure has been linked to increase risks of miscarriages (spontaneous abortions). In a study of Ontario, Canada, farm families, glyphosate use prior to conception was associated with an increased risk of late (between the 12th and 19th weeks of pregnancy) miscarriages.
  • The overview continues with similarly unfavorable reports about its effects on hormones, attention deficit disorder, a variety of wildlife and water.

The U.S. Environmental Protection Agency requires product testing before it releases chemicals into the environment, Hoppin said. She said lab tests focus on genetic, cancer, reproductive and neurological outcomes, but understanding health effects takes time.

“When something is brand new, you just can’t know everything about it,” Hoppin said.

Products remain on the market despite risks because regulating herbicides is difficult, said Scranton, with Women’s Voices for the Earth. Based in Missoula, WVE is a national organization working to eliminate toxic chemicals that harm women’s health.

“It’s really hard to regulate toxic chemicals that affect health, given our current laws,” Scranton said.

The federal Toxic Substances Control Act was passed in the 1970s, and it grandfathered in as “probably safe” some 60,000 chemicals that already had been used, Scranton said. She said the law had a grand vision, but it’s been used poorly and it’s riddled with loopholes.

Plus, Montana is among the states that adopted a pesticide pre-emption law roughly 25 years ago, said Paul Towers, of the Pesticide Action Network of North America. PANNA is based in Oakland, Calif., and works to replace the use of hazardous pesticides with ecologically sound alternatives.

“The industry passed these laws many years ago to make sure that folks in government couldn’t take more steps to restrict these pesticides,” Towers said.

And the EPA allows products on the market when they are known to be harmful, Tower said. He said the body of science shows even in small amounts, pesticides can have a profound impact, especially on children’s health and intelligence.

“That’s what the research continues to tell us. In places where children live, learn and play, we need better protections in place for children,” he said.


Mindful of the harms, some cities have opted to manage certain parks without pesticides. Shelly Connor, associate director of NCAP, said the call from the American Academy of Pediatrics to protect children from pesticides fueled more communities to create parks free of pesticides.

“I think it’s definitely gaining momentum, and it has since we first started putting out the 10 steps on how to get your community a pesticide-free park,” Connor said of the NCAP toolkit.

In Montana, Helena, Bozeman and Whitefish have designated pesticide-free parks, according to NCAP. Connor said a pregnant woman who saw someone spraying a park in her neighborhood where her young son played drove the effort in Bozeman.

“She worked with the city to create a pesticide-free park where the community got together once or twice a year to do dandelion pulls, weed pulls and different things like that,” Connor said.

Mostly, cities are starting pesticide-free parks because parents are pushing for them, she said. Generally, they aren’t concerned about any one specific pesticide or the different active ingredients.

“It’s more about having a space that they can go to with their kids without being exposed to any kind of chemicals,” Connor said.

In most cities, the call to action comes from parents, but in Eugene, it came from a city agency. NCAP is based in Eugene, and there, a conversation with the Parks and Open Space Division unfolded about rolling out NCAP’s pesticide-free parks program in its own backyard, said Kevin Finney, park operations manager.

He didn’t want to be in the position of having to weigh the different scientific studies from NCAP or Monsanto or the National Institutes of Health, but he did want to respond to community values and expectations. So the city embarked on its pesticide-free program, he said.

In 2006, the city selected five parks scattered in different neighborhoods to be managed without herbicides, Finney said. Since then, other neighborhoods have come forward requesting pesticide-free parks and offering volunteers to pull weeds.

“We respond to community values, and what people want in their parks, we will give them,” Finney said.

At least one city made a broad commitment to disavow pesticides, and its program unraveled, he said. Eugene’s program succeeded, he said, because it started small.

Over the years, the city has raised its tolerance for weeds and raised the threshold for spraying, and its pesticide-free parks program has grown. Eugene still uses herbicides, he said, but since 2006, the amount has stayed “flattish” even as parkland acreage “exploded.”

“I think what we’ve tried to do is let the program grow as the public support for it grows so that we’re not pushing it,” Finney said.

In Missoula, Gaukler also talks about the balance of factors Parks and Recreation considers as it manages its land. It relies on legal requirements from the U.S. Department of Agriculture, and it also responds to community values about pesticides, political and social sensitivities to weeds, and even cultural best practices.

“Like most things that we do, there’s science and there’s social science, (and) plenty of opinion,” Gaukler said. “And what we try to do at Parks is meld all those different things to the best of our ability and to stay current on all of those different aspects.”

The Parks department occasionally fields calls from people who are concerned about the use of herbicides, according to a spokeswoman. It hasn’t seen a groundswell against spraying, although one citizen, Daniel Geary, has long been agitating against glyphosate.

“This is the chemical cluster bombing of Missoula’s children by the mayor and his parks managers,” Geary said during last week’s Missoula City Council meeting.

Geary has sent long and strident missives to Parks staff and elected officials about the pesticide, and in his public comment, he said the chemical has been applied just 18 feet away from water at Splash Montana where children play, among other places. He urged the city to stop using glyphosate and purchase a safe vinegar solution from the company Alldown instead.

“If we are to spray, let’s do it with a reputable product that does not poison our children, our pets, our rivers, our drinking water or our playgrounds,” Geary said.

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Reach Keila Szpaller at @keilaszpaller, at or at (406) 523-5262.

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University of Montana, higher education