Our Stolen Futurea book by Theo Colborn, Dianne Dumanoski, and John Peterson Myers


Baton Rouge Advocate
17 November 2002

Uncertain chemical

Weedkiller made in Louisiana is important to farmers, but atrazine may be harming the aquatic environment

Advocate staff writer

LIVONIA -- Like most farmers, Mark Engemann has to worry about weather, insects, weeds, crop prices and labor costs in coaxing a field of sugar cane or corn from the ground to make money.

Now he also worries about whether a herbicide that he sees as one of his best tools -- atrazine -- may be taken from his hands and added to his headaches.

New science is questioning the safety of the herbicide, which has been used for 44 years and is so pervasive in the environment that it can be found in raindrops. The U.S. Environmental Protection Agency has extended a regularly scheduled scientific review period to consider research that could derail use in the United States of one of the most commonly used weedkillers in the world.

"If we lose atrazine, we lose a good herbicide that is one of the most cost-effective herbicides we can use in sugar cane," said Engemann of El Dorado Plantation/Engemann Farms in southern Pointe Coupee Parish.

The EPA is studying research that indicates there's a price for continued use of atrazine.

Tests done in 1998 and since have shown that atrazine is often found in Louisiana at concentrations the EPA says are sufficient to harm the aquatic environment.

The research indicates atrazine and other pesticides may be suppressing immunity in amphibians, allowing parasites and environmental factors to cause deformities -- such as extra legs -- in frogs.

And atrazine concentrations often exceed levels that cause some developing male frogs to grow both male and female sex organs.

John McLachlin, director of the Tulane-Xavier Bioenvironmental Research Center, said the research suggests "the possibility that environmentally relevant doses of atrazine can play hell with the sexual development of frogs."

"It would be a big deal if I came to Tulane Medical School and was a genetic male and had an ovary," he said.

Farmer Mark Engemann holds up a bag of the atrazine he uses in his fields in Livonia.
All of the atrazine made in the United States is made in St. Gabriel by Syngenta. About 300 of the plant's workers are involved in the production and packaging of the herbicide. Nationwide, more than 70 million pounds of it are used in 75 different crop-protection products.

Workers at Syngenta's St. Gabriel plant have filed 10 lawsuits claiming a link between atrazine and their prostate cancers. The Natural Resources Defense Council, an environmental activist group, claims Syngenta is hiding studies that show an increased risk of cancer at the plant.

Health surveys have discovered 17 prostate cancer cases in Syngenta employees or its contract workers since 1985.

Syngenta, which has an annual payroll of about $43.5 million in St. Gabriel, denies allegations of a link between atrazine and cancer. It points to an EPA review that said the elevated number of prostate cancer cases probably is a result of higher-than-normal participation in a prostate screening program for plant employees.

The World Health Organization's International Agency for Research on Cancer and an EPA advisory panel have both said atrazine is not a likely cancer-causing agent, although at one time IARC did classify it as a potential carcinogen.

EPA also said it is concerned about atrazine levels found in drinking water in 28 United States community water systems, including Iberville Parish Water Works No. 3, which serves about 10,000 people.

Monitoring in the early and mid-1990s showed elevated levels of atrazine in that Iberville water supply, but Brian Berthelot, manager of the Iberville Parish utilities department, said monthly tests show the water meets federal standards.

Berthelot said atrazine levels did spike earlier this year in water taken from the Gulf Intracoastal Waterway, the water works' only water source. That prompted the use of powdered, activated carbon to filter atrazine out of the drinking water.

In 1998, state agencies monitored for atrazine in streams in the upper Terrebonne Bay Basin, many of which feed into the Intracoastal Waterway. One in five samples showed atrazine concentrations at or above the level EPA says can harm the aquatic environment.

As a result, Engemann and other farmers began applying their atrazine more carefully. That seemed to help.

However, LSU Agricultural Center weed specialist Jim Griffin said part of the drop might have been a result of several years of drought. Once normal rainfall patterns resumed, atrazine started showing up in higher concentrations in the Iberville Water Works No. 3 intake.

When the Louisiana Department of Environmental Quality and the Louisiana Department of Agriculture and Forestry monitored streams in the upper Terrebonne Bay Basin in 1998, 19 percent of the samples had atrazine levels exceeding 10 parts per billion. Sixteen of 220 samples, or 7 percent, exceeded the 20 parts-per-billion level. Four samples topped 100 parts per billion and the highest concentrations -- from Bayou Maringouin and Bayou Tommy -- topped 200 parts per billion.

EPA water quality standards currently allow up to 12 parts per billion of atrazine in water.

Dennis Demcheck, a water quality specialist for the U.S. Geological Survey, said some cornbelt states show water concentrations of atrazine much higher than those found in Louisiana, but that the pesticide still is pervasive in the Bayou State.

"We have a chronic atrazine problem," he said. "Almost any time of the year, if we look, we can find it … except midwinter."

In March, EPA released a draft scientific review of atrazine as part of the reregistration required of all herbicides every five years. The review says:

"Aquatic ecosystems are at risk from atrazine use, especially those in high-use areas. This is based upon atrazine's toxicity to aquatic plants, associated indirect effects on invertebrate fish populations … and sensitive organisms lower on the food chain. ... Effects are likely to be greatest where concentrations of atrazine in water recurrently or consistently exceed 10-20 parts per billion."

University of California-Berkeley researcher Tyrone Hayes published two papers in scientific journals this year saying atrazine caused developmental problems in frogs at .1 parts per billion, a level one-thirtieth the existing drinking-water standard.

Atrazine-exposed male frogs, both in the laboratory and in the field, had both male and female reproductive tissue, Hayes said. Atrazine levels are generally highest in the spring when tadpoles are becoming frogs.

"It is causing a disturbance in the natural ecology, even in doses that we find in rainfall," Hayes said. His research, funded by the National Science Foundation, was published in May in the Proceedings of the National Academy of the Sciences, a distinguished peer-reviewed journal.

Hayes said atrazine might be making frogs produce the enzyme aromatase, which converts the male hormone testosterone into the female hormone estrogen. The result: genetically male frogs which have both testes and ovaries.

McLachlin, director of the Tulane-Xavier Bioenvironmental Research Center and a pioneer in research on chemicals that mimic or change hormones, praises Hayes' research. He also said he wonders about the larger effect on the population of 10 percent or 20 percent of male frogs having a female gonad and being infertile.

Biology professor and researcher Ann Cheek of Southeastern Louisiana University has been trying to answer that question.

She feminized some fish by exposing them to a substance that mimics a hormone, then raised their offspring. The offspring "developed normally and were able to make eggs and sperm, but genetically something must be wrong because their embryos didn't hatch. I don't know what went wrong."

"It appears that when you have transgendered effects, it may take several generations before you see this decrease in production," Cheek said.

Syngenta, through an independent research group, funded research to review Hayes' first lab results to see if they could duplicate it. They could not, and the panel published a harsh critique of his study, said Tim Pastoor, a toxicologist and Syngenta's head of global risk assessment.

The Syngenta-sponsored scientists then went to South Africa to test both atrazine-exposed and unexposed frogs of the same genus used by Hayes in its natural habitat. They found no problems, Pastoor said.

Hayes took his research to the field and studied leopard frogs in parts of the United States. He recently published his findings in the journal Nature, saying he found similar sexual development problems in the field that he found in his lab.

Pastoor said Syngenta's panel is doing similar studies in the field now and results will be published soon.

Biology professor and researcher Joe Kiesecker of Penn State University studied frogs in the field and looked for differences in those exposed to herbicides like atrazine and those exposed to pesticides. He concluded that the chemicals lowered the immune systems of the frogs, allowing parasites to cause deformities such as growth of extra rear legs. [more on this study...]

Kiesecker said he thinks there may be more than one cause of frog deformities, which were often documented before industrial chemicals were common in the environment.

Pastoor said "Kiesecker is a careful researcher … who has published a fair amount of information on exposure to UVB (ultraviolet B light rays)" and other factors that could be hampering amphibian health.

Syngenta wants more information on the animals Kiesecker tested and on how other factors, such as ultraviolet light, affect immune problems, Pastoor said.

Pastoor said his company has given EPA numerous studies that show atrazine is safe.

· Atrazine is used to control weeds in sugar cane and corn fields across the state.
· It is made by Syngenta in St. Gabriel. Workers there are paid $43.5 million annually in salary and benefits.

· New research shows atrazine may be causing male tadpoles to develop into frogs with male and female reproductive tissues.

· In a 1998 survey, the state found atrazine concentrations of 10-20 parts per billion or higher in at least one in five samples taken on the west bank of the Mississippi River.

· A new scientific review of the herbicide atrazine should be complete by January. It will determine if atrazine can continue to be used and made here.

"In the mid-'90s, Syngenta sponsored a panel through an independent group, and it has done a wide range of studies on alligators, turtles, fish and other aquatic life.

"The overall health and reproductive capabilities of aquatic life and environments have not been impaired," Pastoor said.

He said atrazine is "the most-studied herbicide on the planet and because of that we are real confident atrazine is going to be reregistered."

St. Gabriel plant manager Bob Slaven said he also feels confident.

"Syngenta is a company that is dedicated to product stewardship … and extremely sound environmental and safety programs," Slaven said.

An interim reregistration decision was scheduled for August, but has been delayed until January. A science advisory panel will then be appointed by midyear to review the decision and make a final recommendation in October, Pastoor said.

Larry Lejuene and Butch Stegall of the Louisiana Department of Agriculture worked on the 1998 special state study of atrazine. They said Syngenta's research convinced them the herbicide does not pose a threat to the state's environment.

Meanwhile, Engemann and other farmers wait. Most are cautious about how and when they use atrazine.

Engemann has been farming near Livonia and using atrazine since the 1980s. For most of those years, he grew corn and soybeans, and used atrazine on the corn.

In 1999, he switched from corn to sugar cane and uses atrazine to prepare the fields. He also uses it after the cane has begun to sprout. Some years he has used atrazine to treat the fields after harvest to reduce weeds over the winter.

"It has always been a good, effective, fairly reasonably priced product," Engemann said.

Still, he and other farmers voluntarily cut on their use of atrazine when LSU told them of the high readings.

"We didn't want to lose the chemical," he said.

Griffin, with LSU, said most farmers in the area use one-fourth of what the product label says they can use. They spray more selectively and use tractors instead of airplanes to apply it, which makes the application more accurate and reduces runoff.

Engemann said he might be able to afford more-expensive alternatives to atrazine, but "for farmers who are struggling, atrazine has been the most cost-effective," he said.

Griffin said he doesn't want farmers to have to give up any available herbicides and that he thinks atrazine is safe if used properly.

But, like many farmers, Engemann said he is worried about mounting restrictions.

"I hope we don't get to the point we can't grow our own food here."





OSF Home
 About this website
Book Basics
  Synopsis & excerpts
  The bottom line
  Key points
  The big challenge
  Chemicals implicated
  The controversy
New Science
  Broad trends
  Basic mechanisms
  Brain & behavior
  Disease resistance
  Human impacts
  Low dose effects
  Mixtures and synergy
  Ubiquity of exposure
  Natural vs. synthetic
  New exposures
  Wildlife impacts
Recent Important    Results
Myths vs. Reality
Useful Links
Important Events
Important Books
Other Sources
Other Languages
About the Authors
Talk to us: email