CHILLICOTHE, Ohio — Ross County farmer Ed Julian is the fourth generation in his family to farm the same 340 acres in this part of southwestern Ohio.

Julian laughs when he thinks of the “beating” his soil has taken over the years with various crops, including tobacco and alfalfa hay, among others. Not only does he ponder his fate at times, he wonders if his soil can withstand another generation or two of farmers.

Even more, he’s concerned about the chemicals that go on that soil. “There’s no doubt that the soil gets replenished and farmers like myself need to be good stewards of the land, but if you’re not going strictly organic, there’s some concern when we use any type of chemicals on the crops,” he said. “And I mean any amount of chemicals, as well.

“Nowadays it’s all about profit margins and output. I just think we need to be very careful when we’re using any insecticide, fertilizer or herbicide. The good earth can only handle so much.”

Scientists, environmentalists and farm advocates are pressing the question about whether rewards of the trend toward using 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 month with a series of warnings and calls for government action, including a lawsuit against the U.S. Environmental Protection Agency (EPA).

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: First, 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. Second, some favored technologies are starting to lose their edge as growers have found they must use more chemicals to combat the weeds and crop-damaging pests that biotech seeds were engineered to address.

“Production is growing,” said Pat Sinicropi, legislative director at the National Assoc. 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.”

The debate has focused on when the line of harming health and the environment 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.”

Those on the other side of the debate agree increasing crop production is necessary. “But, if we are going to feed 10 billion people in the next 40 years, we have to essentially double agricultural production,” Borel said.

“We all have to work together. We have to be eyes wide open around the challenges and the risks. 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.”

Just this past week a coalition of more than 2,000 U.S. farmers and food companies took legal action to force government regulators to analyze potential problems with proposed biotech crops and the weed-killing chemicals sprayed over them.

Dow AgroSciences, a unit of Dow Chemical, and Monsanto Co. are among several global chemical and seed companies scrambling to roll out combinations of genetically-altered crops and new herbicides, designed to work with the crops as a way to counter rapidly spreading herbicide-resistant weeds choking millions of acres of U.S. farmland.

Dow representatives say the new chemical combinations and crops that tolerate those chemicals are badly needed by corn, soybean and cotton farmers because weeds increasingly resist treatments.

But opponents argue key ingredients in new herbicides (2,4-D for Dow and dicamba for Monsanto) are in use now and have proved damaging to non-target fields because they’re difficult to keep on target. The coalition represents more than 2,000 farmers and groups, such as the Indiana Vegetable Growers Assoc., the Ohio Produce Growers and Marketers Assoc. and major food processors Seneca and Red Gold.

Today, more scientists are weighing in on this dilemma. Many 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 chemical-intensive crops.

One concern is the level of nitrogen fertilizer runoff into water sources. A study released March 13 by researchers at the University of California-Davis stated fertilizers and nitrates from agriculture are contaminating the drinking water for more than 200,000 residents in California’s farming communities. Researchers say 50 percent of rivers, streams and lakes and nearly 60 percent of bays are impaired because of excess levels of nitrogen and phosphorous.

Insecticides are under the microscope, as well. Twenty-two U.S. plant scientists co-authored a letter in March warning the EPA about a biotech corn that is losing its resistance to plant-damaging pests and could trigger escalating use of insecticides.

Farmers must be trained and approved every year to apply pesticides and take a range of precautions. Lifelong Iowa farmer Dennis Schwab knows the risks; as a corn grower in the nation’s top corn state, the 61-year-old 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,” Schwab said recently. “Yeah, we are concerned about it, but we recognize pesticides are a necessary part of raising crops.”