Don Smith rounded up cattle on his farm. He and his wife, Norma, were stumped when their sheep stopped having lambs and then half the herd died.

Richard Sennott, Star Tribune

Don and Norma Smith joined an investigation of farm-chemical drift. Today, the group releases five years of findings.

Richard Sennott, Star Tribune

Becky Sheets stood next to the “Do Not Spray” sign at the gate to her organic farm in Staples.

Richard Sennott, Star Tribune

Group tracks airborne fungicide

  • Star Tribune
  • May 17, 2012 - 5:32 AM

FRAZEE, MINN. - Don and Norma Smith couldn't understand why their sheep stopped producing lambs in the mid-1990s. When half the animals died mysteriously over one winter, they gave up on the profitable hobby that had won blue ribbons for their kids at the Minnesota State Fair.

It was only later that they figured the problem might be connected to chemicals used on the potato fields that had grown up around their small farm here on the sandy soil in west-central Minnesota.

Now they are among a group of residents releasing findings Thursday from five years of air monitoring for a toxic fungicide sprayed repeatedly every summer on the vast potato fields to protect against devastation from blights.

The report, compiled with the help of the national Pesticide Action Network (PAN), says their 19 monitors, placed on porches, at schools and in yards during the past four years, detected low concentrations of the fungicide in the air in and around Perham 68 percent of the time.

"Many Minnesotans are regularly exposed to [it] in the air they breathe," said Emily Marquez, a scientist at PAN. "Even at low levels, airborne pesticides can raise serious health concerns."

The Environmental Protection Agency (EPA) shares the Smiths' concerns. It considers the fungicide -- chlorothalonil -- a likely carcinogen, based on animal testing, and an irritant to the skin, eyes and respiratory system. And it is extremely toxic to many forms of aquatic life.

Until now, however, the EPA has focused primarily on the risks to people from occupational exposure or eating food sprayed with the chemical. But in 2009 a scientific advisory panel recommended the EPA assess regulated agricultural chemicals for how much they drift and for risks of "bystander exposure from field volatilization." In a routine review launched in March, the EPA intends to assess the health risks from inhaling chlorothalonil.

The Smiths don't know if that's why their sheep died, or if it's why Norma's voice became more gravely, or if it's related to the little boy down the street who developed leukemia. But they and others were worried enough to ask PAN to help them become "grass-roots scientists." They filled out data sheets twice a day in the summer months to prove that even when applied correctly, pesticides and fungicides drift off the fields and into places where people and animals live.

"We don't see evidence of incorrect application," said Linda Wells, Midwest coordinator for PAN of North America. "But it's a highly volatile chemical. It can travel miles from where it's applied."

It will be years before the EPA research on inhalation is complete. In the meantime, say state health officials, data collected by local residents and analyzed by PAN does a credible job of adding to what little science there is. "It's the data that we have," said Rita Messing, a toxicologist with the Minnesota Department of Health's division of environmental health who is familiar with the findings. "We are inclined to believe it until there is other data that is better."

Cash crop

Farmers say potatoes, which have emerged as a valuable cash crop for Minnesota in recent years, would be at risk without the chemical. Chlorothalonil, the most commonly used fungicide in the country, has been used since the 1970s to protect 65 crops, from tomatoes to potatoes, against fungal diseases that can destroy them. In the central and western areas of Minnesota where potatoes are grown on about 50,000 acres each year, it is applied weekly by air or ground applicators.

In particular, it protects against late blight -- the fungus behind the 1850s Irish Potato Famine.

"It has the potential to wipe us out," said Justin Dagen, who grows potatoes on 350 acres near Karlstad, Minn. "We must protect our crop, and chlorothalonil has worked very, very well for many years."

But like most agricultural chemicals, it comes with risks.

The human risk is extrapolated primarily from ingestion data in animals. Still, the EPA considers chlorothalonil highly toxic when inhaled at high concentrations. In recent years, studies in California and Canada have shown that the chemical often hangs in the air after application and even moves beyond the field. Syngenta, the corporation that makes chlorthalonil products, said those studies have not found concentrations high enough to meet the levels of concern established by the EPA.


The Minnesota study began in 2006 and was completed in 2009. The residents set up "drift catchers" similar to those used by California state regulators to test air at 19 locations -- 15 near fields, four in residential areas -- over weeks at a time.

For six weeks the Smiths drove 20 miles twice a day from their farm to collect samples at a monitor outside a private home in the city of Perham. In all, the residents collected 340 samples. They found residue of a number of pesticides, and chlorothalonil in 68 percent of them.

"Every time I was in town I could smell it," said Carol Ashley, one of the pesticide group, who set up a drift catcher at her home near Park Rapids. "It does not stay where it's supposed to."

'Like clockwork'

The health implications are unclear. State health officials said they are concerned about the data gap regarding the risk to people from long-term exposure to low levels in the air.

"It's possible they might affect surrounding communities, especially vulnerable people like children or elderly people," said Messing.

And in Minnesota, the potato fields are concentrated around the string of small towns that stretch along Hwy. 10 up to Fargo, N.D.

"It's intensively used in this area," said Deanna Scher, an epidemiologist with the Health Department. "We have large potato fields in populated areas where chlorothalonil is applied weekly."

But until the EPA makes a decision, sometime within the next 10 years, there are few options, said Greg Buzicky, director of pesticide and fertilizer management for the Minnesota Department of Agriculture. Nearby residents can talk to local farmers and those applying the chemical, he said. Farmers can apply it carefully, or switch to other products that are less likely to drift, he said.

But the Smiths and their fellow citizen-scientists say knowledge alone is a step.

"The sheep were down there every Saturday morning like clockwork when they were spraying with airplanes," Norma Smith said. "If we had known, we could have kept them back."

Josephine Marcotty • 612-673-7394

© 2018 Star Tribune