SEMO center finds groundwater with pesticide levels far above the EPA's maximum limit

In 2004 and 2005, monitors reporting to the U.S. Environmental Protection Agency found potentially harmful levels of the weedkiller atrazine in the South Fabius River and Youngs Creek watersheds in northeastern Missouri. Some studies have shown that atrazine can produce hermaphroditic frogs and male frogs with ovaries and eggs, although the level of exposure has varied in those studies. One study of men who worked in a factory that produced atrazine found prostate cancer levels in those exposed to the chemical were 8.4 times higher than in the general population.

Atrazine, a white, odorless chemical used to control grasses and broad-leafed weeds, is the second most widely used herbicide in the U.S. and is especially popular among Midwest corn growers. It interrupts the photosynthesis process in plants.

"Atrazine works really well," said Dr. John Kraemer, director of the Center for Environmental Analysis at Southeast Missouri State University.

The center has been testing wells in Dunklin and Stoddard counties for atrazine and other chemicals for the past three years. The EPA's maximum atrazine concentration for water is 3 parts per billion. At some times of the year in those heavily farmed counties, the chemical has been found at levels of parts per million instead of parts per billion, Kraemer said. The difference is huge, basically a factor of 1,000.

Kraemer said 80 percent of the wells the center tests in those counties exceed the EPA limits for atrazine and other toxic chemicals.

The European Union, which employs a more precautionary model for regulating chemicals than the U.S., has banned atrazine. In the U.S., the EPA renewed its approval of the herbicide in 2006 while sanctioning further tests of watersheds, tests conducted by the chemical's Swiss manufacturer, Syngenta. The EPA reviewed 19 laboratory and field studies and concluded that atrazine does not adversely affect gonadal development in amphibians and that additional testing on its effects is not necessary. The EPA is reviewing its conclusion that atrazine poses no cancer risk to humans. But drinking water containing atrazine for long periods may damage the heart and liver. The Center for Environmental Analysis often finds high levels of atrazine in combination with other chemicals, such as the insecticide malathion. When this occurs, findings at such high levels are a concern. "It is for me," Kraemer said. "... The combination can be adverse."

Kraemer said toxic chemicals usually are tested individually. That is all the law requires. Chemicals rarely are tested in combination with another. But he is finding other chemicals like the powerful pesticides phorate and azinophos methyl at levels as high as atrazine's.

Kraemer thinks multiple effects need to be tested. Terry Timmons, the DNR's groundwater monitoring section chief in Jefferson City, Mo., said that type of testing is expensive. "The chemical registrants are only worried about getting registered for their product," he said.

But Kraemer's findings of multiple chemicals in high concentrations in private Bootheel wells is a concern, Timmons said. "From an environmental standpoint you start to worry about the mixture he might be seeing."

Drilling a deeper well could be the solution to the presence of chemicals but presents an aesthetic problem because deeper water contains a large amount of iron. "You would not get good quality water without an iron removal process," Timmons said.

The Department of Natural Resources studied the presence of farm chemicals in groundwater in the shaded areas of the map.

Forty-two percent of Missouri's population depends on groundwater for drinking water. Municipal water systems monitor their own drinking water. The DNR tests public water supplies serving at least 25 people or 15 service connections. The state does not test private wells, although the Department of Health and Senior Services will conduct tests if there are reasons to suspect the quality of the drinking water.

From 2001 to 2006, the DNR did monitor private wells to test shallow groundwater for four agricultural chemicals for a report to the Missouri Department of Agriculture and the EPA. The monitoring network sampled 190 private wells throughout the state, the greatest concentration in the Bootheel. The Bootheel is considered especially vulnerable to chemicals because of the large amount of row crops, the permeable ground material and the shallow water table, usually within 20 feet of the surface.

The DNR tests for the herbicides alachlor, atrazine, metolachlor and simazine were all within EPA limits for the years 2001 to 2006. The department tested 11 wells in Butler County and 31 in Stoddard County.

Of the wells monitored, 118 were built to state construction standards. The wells in the alluvium of the Bootheel were exempt from state construction rules, which call for a protective casing and screens. The ease of finding water in the Bootheel's shallow water table is why so many wells don't meet state standards. "In the Bootheel you can take a well point and sledgehammer and make a well in your backyard," Timmons said.

Most of the wells the Center for Environmental Analysis tests are shallow water wells with no protective covering. "It's like a big straw in the ground," Kraemer said. Some have been dug by hand. Most are only 10 to 15 feet deep.

Timmons said of those wells, "You might as well be taking a glass and drinking out of a road ditch."

Timmons said 100 feet is a typical depth for an unconsolidated well, a well drilled through the sand, gravel and clay deposits typical in the Bootheel. But some of the private wells the DNR tested in Butler and Stoddard Counties were much shallower, as little as 16 feet deep.

Timmons thinks variations in the construction quality of wells and the tendency of most of the DNR wells to reach deeper into the aquifer could account for part of the difference between his agency's and the Center for Environmental Analysis' findings.

Additionally, the pesticides tested for are formulated to stay in the soil and not leach, he said.

But, Timmons added, "I always thought it seemed odd in the Bootheel that we never detected problems with nitrates and pesticides in an area of the world as intensively farmed as anywhere."

Kraemer suggests that differences in when, where and how deep the DNR monitored groundwater could account for the variations with the CEA's findings. There is no testing protocol for private wells.

The Center for Environmental Analysis contracts with private landowners who request testing. "A lot of folks are curious to see what's in there," Kraemer said. The results are reported only to the landowner.

Private wells are not regulated by any government agency. "They are not part of a drinking water system. There are no rules about what comes out of those wells," Kraemer said.

Atrazine is not the only chemical that could pose a threat in watersheds. The organic pesticides chosen as a less toxic alternative when DDT was banned can break down and infiltrate sediments in streams. The lack of sun can extend the half-life of those organophosphates.

Kraemer said atrazine can be found readily because it is so widely used. More than 65 percent of the corn crop in the U.S. is treated with atrazine. The percentage in Missouri is even higher. "It will be used more if we get ethanol plants," he said.

Dr. Tyrone Hayes, a researcher at the University of California at Berkeley, has led the way in pointing out the effect atrazine can have on amphibians. In the two Missouri watersheds, atrazine was found in concentrations of 10 ppb. Wildlife biologist say atrazine can affect the behavior of fish in a lab at concentrations of 0.5 ppb.

Hayes originally was hired by Syngenta's consulting firm to study the chemical's effects but withdrew from the study, saying the company was trying to bury his findings. Some subsequent researchers say Hayes' findings can be duplicated but not at the low levels he tested.

sblackwell@semissourian.com

Devin Vitt measured a sample of creek water for the level of dissolved oxygen. (Fred Lynch)

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