Ag chemicals and drinking water: A modern conundrum
By ERIKA HAYASAKI
News-Gazette Staff Writer

   In East Central Illinois, an area that is 70 percent agricultural, it is not uncommon for chemicals to show up in drinking water.
   And those chemicals may cause health problems.
   Atrazine, the most widely used crop pesticide in the state, has been linked to cancer in rats, and studies have shown it reduces the weight of their offspring. Such concerns have persuaded health experts to recommend humans not consume high levels of the chemical.
   Nitrates, chemicals found in fertilizer, have been proven to cause "blue baby syndrome," a disorder in which hemoglobin cannot carry oxygen in infants.
   A.G. Taylor, an agricultural adviser for the state Environmental Protection Agency, said about 27 water supplies have had atrazine levels above compliance since the summer of 1992, when monitoring began.
   Taylor estimated that 10 to 12 water supplies have been above nitrate compliance levels in the last few years. Although there are regulations on how much nitrate farmers are allowed to use on crops, Taylor said it is important for farmers to pay close attention to its use.
   "Farmers, in regard to the use of nitrogen, need to take a close look and review their application to make sure they're not using more than they need to use," he said. "They may consider other practices that will lead to more efficient uptake and utilization of the crop."
   Ed Mehnert, a hydrologist for the Illinois State Geological Survey, said chemicals such as nitrates and atrazine do show up in water supplies in East Central Illinois. They are most frequently found in surface water supplies and man-made wells, he said.
   "We have found atrazine above (required levels) in very few wells, but we do find it," Mehnert said. "We tend to find it in water supplies that are less than 50 feet from the surface. We tend to find higher concentrations in dug-wells, primarily dug to serve households in areas where there is no outstanding aquifer. There are many of those in this area."
   The EPA is re-evaluating the safety standard for atrazine levels in drinking water and the amount used as agricultural pesticides, said Tom Hornshaw, manager of the toxicity unit for the state Environmental Protection Agency.
   "The (Environmental Protection Agency) is examining exposure on farms, through food and how much winds up in drinking water," Hornshaw said. "It may even result in a raising or lowering of the drinking water standard level of atrazine, or to regulations on how much can be left on crops."
   Taylor said some water filtration systems have been upgraded due to atrazine regulations. But the most effective way to reduce the amount of atrazine that gets into drinking water is to reduce its existence in run-off, reduce its usage rates, use different chemical pesticides or install filters along streams, he said.
   The current EPA safety standard for atrazine is 0.002 milligrams per liter of water. For nitrates it is 10 milligrams per liter. Once levels pass these limits, safety precautions go into effect.
   Water companies may issue public warnings if nitrate chemical levels are too high, and give away bottled water. Danville's Consumers Illinois Water Co. has done so several times in the last few years.
   Nitrate problems in drinking water occur in flat land areas with surface water reservoirs such as in Georgetown, Decatur, Danville or Bloomington.
   Plants use up nitrates, so the longer the growing season is delayed, the more nitrates are left in the soil to be washed into lakes and streams by the rain.
   Organisms in soil convert organic nitrogen to nitrates. Nitrates are picked up in the water as it passes through soil and moves through subsurface drains, which empty into ditches and rivers.
   There are 106 surface water reservoirs in Illinois, according to Taylor.
   Nitrogen problems are uncommon in ground-water reservoirs such as the Mahomet Aquifer, which supplies water to Champaign-Urbana, Rantoul, Clinton, Mahomet, Monticello and Paxton. Nitrates will not carry through the soil into deep water reservoirs.
   "In shallow aquifers you tend to find higher levels of nitrates; it tends to be problem in dug wells too," said Mehnert.
   There are 1,127 groundwater reservoirs in the state.
   Atrazine problems are also uncommon in ground-water supplies because atrazine is attached to soil particles and it won't move into the deep water reservoirs. It gets into surface water reservoirs through run-off of eroded soil particles.
   Some farmers put more nitrogen fertilizer on their crops than they need, but there has been a lot of education about its use, said Kent Mitchell, a University of Illinois professor of agricultural engineering.
   He doesn't think reducing the amount of nitrogen used on crops will reduce its levels in water supplies.
   "I don't believe eliminating or reducing the amount of nitrogen applied to crops will have a short-term effect in the amount of nitrates in surface water for our area," he said. "These are very rich soils and there is so much organic nitrate in the soil that when it warms up it moves through the soil into water."
   But it is important for farmers to comply with chemical regulations, Taylor said.
   The safest way to prevent health effects is to reduce the amount of contaminants getting into the water beforehand, rather than waiting to remove them after they have already moved into water, Taylor said.
   
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