(Reuters) - Scientists, environmentalists and farm advocates are pressing the question about whether rewards of the trend toward using more and more crop chemicals are worth the risks, as the agricultural industry strives to ramp up production to feed the world's growing population.
The debate has heated up in the last several weeks, with a series of warnings and calls for government action including a lawsuit against the U.S. Environmental Protection Agency.
Critics say they fear the push to increase global crop production is translating into mounting health and environmental dangers. As usage expands in some areas, agricultural chemical residues have turned up in water supplies and air samples of U.S. farming communities.
The concerns are rooted in two converging trends:
Growing global demand for food, fuel and livestock feed is pushing many farmers to apply more herbicides, insecticides and fertilizers to crops, hoping to boost production.
At the same time, some favored technologies are starting to lose their edge. Some growers have found they must use more chemicals to combat the very weeds and crop-damaging pests that biotech seeds were engineered to address.
"Production is growing," said Pat Sinicropi, legislative director at the National Association of Clean Water Agencies, an organization of municipal water interests. "The pressure on agriculture is mounting to squeeze as much yield out of their land as possible, which is driving more and more chemical use."
Few would dispute that misuse of agricultural chemicals can harm health and the environment. The debate has focused on when that line is crossed, with industry saying U.S. regulatory oversight is already strong enough to ensure safety.
"With any technology there is risk," said Jim Borel, executive vice president of DuPont, which has projected strong growth in sales of insecticide, herbicide and pesticide products. "People tend to focus on either the problems or worse yet the fears that people create about potential problems.
"But," Borel said in an interview, "if we are going to feed 10 billion people in the next 40 years we have to essentially double agricultural production. We all have to work together. We have to be eyes wide open around the challenges and the risks."
Those on the other side of the debate agree that increasing crop production is necessary.
"To feed a growing world population, we have to intensify crop production, but we can't do so at the expense of the natural resource base," Teresa Buerkle, a spokeswoman for the North America office of the Food and Agriculture Organization of the United Nations.
Where industry says regulation is adequate, critics say it is often lacking. They want the government to do more in-depth examination of the impacts of the chemicals in use and change the incentives that encourage farmers to grow more corn and other chemically intensive crops.
One concern is the level of nitrogen fertilizer run-off into water sources. A study released March 13 by researchers at the University of California, Davis, said fertilizers and nitrates from agriculture are contaminating the drinking water for more than 200,000 residents in California's farming communities.
That study came as a separate coalition of water authority officials, pollution control administrators and sustainable agricultural groups calling themselves Health Waters Coalition asked Congress to address excessive use and runoff of agricultural fertilizers in the new Farm Bill.
The group cited data from the U.S. Environmental Protection Agency indicating that more than 50 percent of rivers, streams, and lakes and nearly 60 percent of bays and estuaries are impaired because of excess levels of nitrogen and phosphorus.
"Nitrogen pollution is considered by scientists among the handful of most serious impacts on the environment that humans cause. It has been increasing," said Doug Gurian-Sherman, a plant pathologist at the Union of Concerned Scientists, a scientific policy group.
"More and more scientists are speaking up."
Insecticides are also a concern. Twenty-two U.S. plant scientists co-authored a letter March 5 warning the EPA about a biotech corn that is losing its resistance to plant-damaging pests and could trigger "escalating use of insecticides."
The Natural Resources Defense Council (NRDC), an environmental advocacy group, has taken its concerns to court, filing suit against the EPA on February 23.
The NRDC accuses EPA of not adequately addressing the health threats of 2,4-D, an ingredient in the Agent Orange defoliant used in Vietnam that prompted lawsuits from veterans and others who later contracted cancer. The chemical now is being increasingly used to help fight back "super weeds" that resist glyphosate, also known as Roundup.
2,4-D is an herbicide that's been registered for use in U.S. crops since 1948 but may now come into far more widespread usage as Dow AgroSciences, a unit of Dow Chemical, seeks government approval for biotech crops engineered to thrive despite dousings of 2,4-D.
Complaints of ties to cancer have dogged the chemical for decades but U.S. regulators have said that research data is insufficient to make a direct link.
A scientific study published in January in the journal BioScience noted that nationwide herbicide use could see a "profound increase" if the new biotech crops being developed see the same rate of adoption that Roundup Ready crops.
Roundup use became so pervasive after the introduction of Roundup Ready soybeans 16 year ago that last summer, researchers with the Geological Survey said significant levels Roundup were detected in air and water samples in Iowa and Mississippi. More than 88,0000 tons of glyphosate were used in the United States in 2007, up from 11,000 tons in 1992, according to the U.S. Geological Survey.
Critics of 2,4-D fear a similar rise in the use of that herbicide.
"EPA is dragging their feet on this issue," said Gina Solomon, senior scientist with the NRDC. "They need to grapple with the science and the current situation where U.S. agriculture is on the cusp of the vast increase of the use of this chemical."
Farmers are well aware of the poisonous possibilities of the chemicals they use, and must get trained and approved every year to apply pesticides, and take a range of precautions.
Life-long farmer Dennis Schwab knows the risks. As a corn grower in the top U.S. corn state of Iowa, 61-year-old Schwab has become an expert in the array of toxic chemicals used to fight bugs, weeds and disease.
"Our exposures are higher than the general population ... yeah we are concerned about it. But we recognize pesticides are a necessary part of raising crops today," he said..
Editing by David Gregorio