A battle is brewing in the corn and sorghum fields of Kansas and across the U.S, where farmers have applied the herbicide atrazine to kill broadleaf and grassy weeds for decades.

Generations of farmers have relied on atrazine, and for many it's a guarantee that their crops will be as bountiful as weather permits. Yet, for some environmentalists, atrazine is seen as a risk for wildlife and possibly people.

Now, 50 years after farmers first began using the herbicide, the fight over its benefits versus its possible harm is hitting the courts after five Kansas cities and a water district signed onto a national lawsuit in March against the weed killer's maker, Syngenta.

The cities of Marion, Dodge City, Plains, Carbondale, Oswego and Miami County Rural Water District No. 2 are among 16 water systems in six states asking for more than $75,000 each to cover the expense of treating water for atrazine. 

Moreover, attorneys for the case say more cities are expressing interest in the case, and possibly more in Kansas.

"There are definitely more coming, there is no question about that," says Scott Summy, with the Texas-based law firm Baron and Budd, which is representing the cities in the case. "Atrazine has been a problem that has plagued public water systems for years."

Yet in southwest Kansas, where corn and sorghum fields dot the landscape, farmer Greg Shelor echoes the concerns of many others in a state reliant on the agriculture economy.

"You have to understand," Shelor said while planting corn last month near his Minneola-area farm. "We have had this chemical for over 50 years, and there have been studies done over the last 50 years. The EPA has looked at it numerous times and it has all been approved."

Atrazine, he says, has become an important, affordable and effective tool in an effort to feed the world.

Across the fertile fields of Kansas, where wheat has always been a mainstay, crops like corn and sorghum are expanding. The state's farmers are expected to plant 4.7 million acres to corn this year — the largest acreage since 1936.

One of the most widely used herbicides in the U.S., atrazine is applied to 60% of the nation's corn crop and 75% of the sorghum crop every spring.

Testifying to its effectiveness are farmers like Jay Warner. The McPherson County operator says he wouldn't be able to grow sorghum without it. It kills weeds while leaving the corn and sorghum crop alone. It's affordable, long lasting and doesn't readily dissolve in water. 

Each year, American farmers apply an estimated 75 to 80 million pounds of the herbicide, according to the Environmental Protection Agency. Without atrazine, farmers could see increased costs in inputs and productivity loss — costing an estimated $28 an acre.

In all, according to a decade-old agency report, eliminating atrazine would cost farmers about $2 billion annually in lost crop yields — roughly 9 bushels an acre — and in substituting herbicides that are more expensive.

Jere White, executive director of the Kansas Corn Growers Association and the Kansas Grain Sorghum Producers Association, pointed out that a decade ago, corn prices were lower than today — around $2 to $2.50 a bushel. 

"The average farmer, say has 1,000 acres of corn and sorghum," White says. "We're talking about taking $28,000 out of his pocketbook, $28,000 not being spent on a different truck or tractor."

Moreover, he says, atrazine is a critical tool for use in conservation tillage and no-till systems — farming methods that eliminate plowing or reduce tillage.

Atrazine works so well because it doesn't bind up with crop residue. Instead it moves with water, allowing it to get down into the soil where the seeds germinate, White says.

"We'd see no-till go by the wayside," he says, noting farmers would have a tough time keeping up with the demand to feed a growing global population without the "tools needed."

Companies like Syngenta have been researching alternatives to atrazine for years, he says. Yet 50 years after its inception, they still haven't come up with anything as effective. Unlike other options that work on specific weeds, farmers can use atrazine over a spectrum of broadleaf weeds.

Also, some are finding Roundup Ready technology has some weed resistance, with farmers applying atrazine as a supplement. 

"If atrazine was gone, if you don't think farmers need atrazine, what do you recommend farmers use?" White asks.

Nevertheless, atrazine is a big rallying point for environmentalists. They contend the chemical is a health risk to humans, noting it washes into surface water and eventually finds its way into drinking water, especially in areas of the Midwest where the chemical is more widely used.

According to a U.S. Geological Survey study released in 2006, atrazine was found, together with deethylatrazine — one of its degradates, or natural decomposition breakdowns — in about 75% of streams and 40% of groundwater samples collected in agricultural areas across the nation.

The Natural Resources Defense Council, a group vocal about potential health problems atrazine could cause in both wildlife and humans, recites these figures. Its Web site points to a study conducted by a University of California professor that suggests low levels of atrazine alter the development of sex characteristics in male frogs.

Their efforts, along with news stories by national media, including a New York Times story headlined, "How much weed killer do you want in your drinking water?" have spurred the EPA to instruct its Scientific Advisory Panel on pesticides to re-examine atrazine's risks. 

White also is chairman of the Triazine Network — a group that includes interests from the California fruit industry to Florida's fruits and vegetables, some of which use the herbicide simazine — also part of the triazine class. He attended the EPA's independent scientific advisory panel meetings in late April, giving input on the industry's behalf.

"This has huge implications," White says. "There are 30 commodities out there" using some type of triazine.

Now small cities across the Midwest are taking on the issue, as well. In March, attorneys with the firm Baron and Budd filed a class-action lawsuit against atrazine manufacturer Syngenta in U.S. District Court in southern Illinois. The communities want Syngenta to pay for the cost of removing the chemical from the drinking water.

The lawsuit claims atrazine exposure has been linked to birth defects, low birth weights and premature births. 

An April 2009 article in Acta Paediatrica, a peer-reviewed monthly journal on international pediatric research, identified a recurring seasonal increase in U.S. birth defects for babies conceived from April through July — relating it to the season when agrichemicals are applied.

The data, compiled from 1996 to 2002 by the Centers for Disease Control and Prevention, came from an assessment of more than 30 million live births. Two of the researchers were with the Indiana University School of Medicine.

Under the Safe Drinking Water Act, public water systems test for atrazine levels quarterly, according to the Kansas Department of Health and Environment. Treated water can't exceed an annual average of 3 parts per billion, and compliant water systems can test once a year. 

Also, says EPA Spokesman Dale Kemery, concentrations of atrazine and its chlorinated degradates must be below 37.5 ppb as a 90-day rolling average. 

Single-day measurements cannot surpass 298 ppb.

Dave Waldo, chief of KDHE's Public Water Supply Section, says only one city in Kansas has violated the standards since 2004. That was Beloit in 2005, when levels that June reached above 40 parts per billion — thus increasing the public water supply's annual atrazine average. 

Presently, Beloit is not part of the lawsuit. The city was among 150 community water systems across the Midwest and about 30 in Kansas closely monitored by the EPA. The city's 1-day atrazine levels also spiked to more than 41.61 parts per billion in May 2008.

However, Kemery says, none of the cities still in the study — which total about 100 at present — have EPA violations.

Atrazine tends to spike during the spring planting season — the typical time atrazine-containing herbicides are applied. 

In Kansas, only six cities spiked above 3 parts per billion during a 2006 study, and none exceeded the EPA's annual requirement.

Nevertheless, attorney Summy argues even a little bit is too much.

"This stuff is under the (maximum containment level), 3 parts per billion, so no one should be concerned about it because it is under that level," Summy said of what supporters argue. "Our point is people shouldn't be drinking atrazine at all."

Dodge City was once known as the "wickedest little city in America" — the area outlaws roamed, the endpoint of cattle drives, the place where Wyatt Earp and Bat Masterson once served as marshals.

During the city's Old West heyday, cattle drovers brought roughly 7 million head of Texas longhorns up the Western Trail during an 11-year period starting in 1874.

These days, its economy still centers on agriculture — including packing plants and feedlots, as well the thousands of acres of cropland, which keeps those industries thriving.

Corn rows flourish under center-pivot irrigation across western Kansas, receiving a drink from the Ogallala Aquifer situated directly underneath. The same aquifer supplies the drinking water for the region's cities. 

Minneola farmer Greg Shelor lives less than a half-hour from Dodge City, a regional hub many area farmers, including himself, frequent for parts and supplies.

A city so entwined in agriculture being part of an atrazine lawsuit came as quite a surprise, he says. 

Water contamination lawsuits aren't new with Dodge City. Earlier this decade, the city signed on to another Baron and Budd class-action lawsuit involving MTBE — a gasoline additive used to make fuel burn cleaner. One of the city's wells was contaminated and needed cleaned. The attorneys were able to secure the city about $1 million in 2008.

In early 2009, Baron and Budd approached Dodge City about the atrazine case. The city officially signed on to the lawsuit in spring 2009, says city clerk Nannette Pogue. The city's involvement, however, didn't surface until March of this year when the case was filed and the city was listed as one of the plaintiffs.

City attorney Brad Ralph says council members discussed the lawsuit with attorneys and city manager Ken Strobel in executive session. No formal action was taken on the matter, but council members instructed Strobel to deal with the lawsuit proceedings.

Strobel requested Summy answer all questions on the lawsuit.

Dodge City Mayor E. Kent Smoll, however, said he was concerned what it would cost the city if it had to clean up a well. 

"Atrazine is a good chemical that the farmers use," he says. "And this is not designed to hurt the farmer, not at all. But if we end up with any atrazine within our wells, it becomes very expensive to clean them."

According to the state, Dodge City wells are well below the 3 parts per billion threshold. Many of the city's wells didn't test positive for atrazine at all in 2008. Two wells tested for atrazine, one measuring 0.11 parts per billion and another at 0.1 parts per billion.

The highest atrazine level was in March 2005, with a well hitting 0.8 parts per billion.

Atrazine is more commonly found in surface water, White says, especially in eastern Kansas, because runoff from fields filters directly into streams, reservoirs and ponds — not necessarily groundwater. Groundwater contamination in western Kansas, however, is small, he says.

"The highest (Dodge City) ever saw was 0.8 on a 1,000-fold safety standard," he says. "You are more at risk driving down the highway at 3 mph."

Minneola farmer Shelor, who is preparing to plant grain sorghum on his southwest Kansas fields this month, says the use of atrazine is a lot different from when he started farming 35 years ago.

He and other farmers apply a lot less of the product than they once did, and he relies on no-till practices to curb runoff of soil and water.

"We don't have the water runoff," Shelor said of his no-till and other best management practices farmers have implemented over the years. "Farming practices have changed, which means the safer use of atrazine."