A report released this fall argues that pesticides have done more good than harm as they’ve bolstered food production across the United States and Canada — and that their application should be expanded to help feed the world’s growing population by 2050.

The report, released as Issue Paper 55 by the Council for Agricultural Science and Technology, a nonprofit backed by companies like Dow AgroSciences and groups like the Virginia Farm Bureau Federation, states that pesticides have contributed to greater crop yields while lessening the legwork required to combat pests and increasing farmers’ incomes.

Overall, pesticides have “improved the prospects for long-term sustainable food production,” the paper states.

But a growing body of research and advocates would call that thesis into question, or at least pose another question, “At what cost?”

A decade-long study by the U.S. Geological Survey also released this fall found that the presence of pesticides continues to be a concern for aquatic life in many of the nation’s rivers and streams. The report found that the presence of pesticides in the water ebbed and flowed with new regulations that affected their use on nearby lands.

It suggested that more research is needed to determine the full effects of pesticides on natural resources.

“While pest management is needed… (CAST’s paper) does not address the consequences of pesticides,” said Ruth Berlin, executive director of the Maryland Pesticide Network, an Annapolis-based coalition that researches the risks of pesticides for both humans and the environment.

The report’s authors “have the gall to say that the benefits outweigh the risks when we don’t even know what all the risks are yet because of a lack of oversight by the U.S. EPA,” Berlin added.

When it comes to local water quality, scientists have found higher incidences of intersex fish in parts of the Shenandoah and Susquehanna rivers that run through lands in intensive agricultural use. (See “Intersex fish linked to areas with high ag, wastewater runoff,” October 2012.)

Toxic contamination in the Bay and its tributaries will be a larger part of the discussion going forward as the latest Chesapeake Bay Watershed Agreement, signed in June, pledges to broaden its focus on these sources of water pollution.

Past efforts to restore water quality in the Bay have largely focused on imbalances in nutrients like phosphorous and nitrogen, but biologists say chemical contaminants — from fertilizers in farm fields to weed killers in suburban neighborhoods — may pose a more direct threat to human and aquatic life.

Meanwhile, the debate rages on about how to best feed a world population that is forecast to top 9 billion people by 2050. Proponents of large-scale agriculture say their solutions — including pesticides, herbicides and genetically engineered crops — are still the best on the table.

“In order to achieve those yields that are going to be required in 2050, we need to look at the availability of tools and how pesticides fit into that,” said Stephen Weller, a professor of horticulture at Purdue University and co-author of the report, during a panel discussion on the topic in November at the American Farm Bureau Federation headquarters in Washington, DC. “We believe that pesticides will play a role in increasing the ability to meet the demand for food.”

Weller said his research showed that pesticides helped increase yields by more than 30 percent. Currently, 20–50 percent of harvested crops in storage are lost on a worldwide basis, Weller said, a figure he said pesticides could help reduce.

“If you ask any farmer that uses pesticides why they use them, they help reduce the risk of loss,” Weller said.

He then added a caveat that the report’s contributors are not condoning the use of pesticides (a category that includes herbicides, fungicides and insecticides) to avoid risk “whether we need them or not.”

That, Weller said, is what led to pesticide resistance and “super weeds” in this country, and it’s a problem he doesn’t want to see exported to other countries. When working with farmers in Africa, Weller says he and other researchers encourage integrated pesticide management programs that use a suite of the right pesticides at the right times for the most effective results.

But Berlin and others say there are better ways to feed the world that the report dismisses, such as small-scale agriculture that creates healthier plants to combat disease and pests.

“Their main thing is that pesticides are necessary to feed the world, but neonicotinoids are killing the bees we need for one third of the food we eat,” she said.

Jack Housenger, director of the EPA’s Office of Pesticide Programs who sat on the panel with Weller, said he’s getting hundreds of e-mails from consumers asking him to ban the neonicotinoids category of pesticides, which research has linked to reduced honeybee populations.

His office is in charge of approving around 1,200 active ingredients in pesticides for sale on the market using a risk-benefit analysis. Pesticide registrants have to submit data on the impact their product would have on human and environmental health and prove its use is worth the risk.

For example, he said, the risks that West Nile virus or Lyme disease pose to human health if transmitted by insects are greater than the risk posed by the chemical DEET that’s in bug sprays.

“I think we’re shifting more and more toward safer chemistry,” Housenger said. “Unfortunately, what’s safer for humans may have a bigger impact on the environment side, but, in general, those shifts have been good ones.”