With the growing demand for organic foods in the U.S., there has been a backlash from agribusiness groups, companies and individuals who see organic as a threat to their interests. These critics accuse the organic industry of using deceptive marketing practices to get consumers to pay more money for organic food. Another line of attack has been that organic farmers use lots of pesticides, some of which are more toxic than those used by conventional farmers.

The reality is that some organic farmers do use pesticides but such products are primarily derived from natural substances, go through a strict regulatory approval process to ensure they are not harmful to the environment and human health and are only allowed to be used when other pest control methods aren't successful.

The fact is that the organic farming and food movement is based on producing healthier foods without the use of toxic pesticides.

25 Organic-Approved Synthetic Pesticides vs. 900 Conventional

However, organic farmers, like their conventional counterparts, face challenges with weeds, insects and diseases. To help address those challenges, the National Organic Program allows the use of certain natural-based and synthetic substances as pesticides. The National Organic Program's National List of Allowed and Prohibited Substances details about 25 synthetic products that are allowed to be used in organic crop production. These include alcohols, copper sulfate and hydrogen peroxide. By contrast, there are some 900 synthetic pesticides approved for use in conventional farming.

There are also many natural-based substances used as pesticides that are allowed in organic farming. These include neem oil, diatomaceous earth and pepper.

"When you look at the substances themselves and not at the use rates, organic represents the least toxic set of substances," said Nate Lewis, farm policy director at the Organic Trade Association. "The difference is pretty striking."

Most pesticides allowed for use in organic farming are derived from plants or bacteria. "They have their roots in nature," said Charles Benbrook of Benbrook Consulting Services, an organic consulting firm.

The majority of organic-approved pesticides are used in fruit and vegetable production, said Lewis. Very few are used in organic grain production.

"Least Toxic Pesticides Available"

According to Lewis, pesticides approved for organic crop production must go through the most rigorous review of all pesticides. All pesticides must first be reviewed by the U.S. Environmental Protection Agency (EPA) to determine their toxicity. EPA sets tolerances, "which are the maximum amount of a pesticide allowed to remain in or on a food." If it is a synthetic pesticide to be used for organic farming, the National Organic Standards Board then reviews it and will recommend whether or not to allow it to be added to the National List. Then, the Organic Materials Review Institute (OMRI) or the Washington State Department of Agriculture will review the product to ensure it complies with the national organic standards.

According to Lewis, just one synthetic pesticide approved for organic farming has been assigned an EPA tolerance—spinosad, an insecticide derived from a soil microorganism. Other synthetic pesticides on the National List, as well as the natural-based substances, are considered safe enough that they don't even need an EPA tolerance.

"The EPA considers organic-approved pesticides to be the least toxic and most safe pesticides, so safe they don't even need to establish a tolerance for what's healthy or what's safe on crops," Lewis said.

One of the most widely spread myths about organic-approved pesticides is that organic farmers use Rotenone, a broad-spectrum insecticide known for its toxicity. While it has been used in the past, the current reality is that the EPA has banned Rotenone for use in the U.S, though Lewis says it is still used in some countries that grow organic bananas. "The NOSB [National Organic Standards Board] has passed a recommendation to prohibit it outright. We are awaiting NOP [National Organic Program] action on that."

Copper Controversy

Critics also cite the use of copper-based pesticides, which are used as fungicides in organic and conventional fruit production.

Copper does have issues. Kelsey McKee, OMRI's review program and quality director, cites documents from the U.S. Department of Agriculture and EPA that describe concerns with the use of copper.

"In general, these concerns include adverse effects on soil microorganisms as well as adverse effects on human, aquatic and terrestrial life during farm level application or from residuals in food," she said.

In an October 2015 review of copper, the National Organic Standards Board acknowledged that it is "both harmful in the environment when misused and absolutely necessary to grow many crops to protect against disease."

The National Organic Standards Board called for additional study on copper for the next review of the material to see if it should continue to be on the National List.

In a comment to a Scientific America article on organic pesticides, Rob Wallbridge, an organic farmer in Quebec, said that copper is not absorbed by plants and washes off "which is good for risk of consumer exposure." He also said that organic certification standards "require monitoring and restrict producers from using copper sulfate if copper is accumulating in the soil at excessive levels."

Copper is also exempt from an EPA tolerance and is an essential nutrient, according to Brian Baker, consultant at Belcairn Concerns and former research director at OMRI.

Baker emphasizes that conventional farmers also use copper. "If they think it is so bad, why don't they stop using it?"

Pam Marrone, CEO and founder of Marrone Bio Innovations, agreed. "Organic growers get flak about copper, but conventional farmers use a lot more copper than organic farmers."

She also said the copper formulations used by conventional farmers contain higher risk inert ingredients than formulations used in organic production. "The inert ingredients in organic approved copper have to be on the approved list for organic and are food-grade and low risk," she said.

Marrone, whose company develops biopesticides for organic production, said there are organic and OMRI-approved alternatives to copper on the market. These include Zonix and Polyversum and her company's Regalia. The OMRI Products List also includes non-synthetic alternatives such as biological fungicides and botanical extracts such as cinnamon oil and clove oil.

Foliar Spray Bt Not the Same as GMO Bt

Then there is the debate over organic-approved Bt insecticide versus genetically engineered Bt crops. Critics say the organic industry is hypocritical by allowing the use of a foliar Bt spray to kill insects while opposing GMO crops containing genes from the Bt or bacillus thuringiensis bacterium.

Benbrook called such criticism spin. "It's a completely different situation. Bt toxins in GM sweetcorn are inside the kernel and remain there when the corn is cooked and eaten. People who eat that sweetcorn will get a high dose of Bt toxins."

By contrast, the Bt foliar spray breaks down quickly and doesn't remain on the plant. "There is zero human exposure to foliar Bt spray," Benbrook said. "Implying that the GMO Bt is the same as the foliar spray is a lie."

Pesticides May Be Used Only as a Last Resort

Perhaps the most important point in the discussion about the use of pesticides in organic agriculture is the fact that the organic rules require that approved synthetic pesticides be used only as a last resort.

"The standards say you must apply practices like having cover crops and crop rotations and things that create health in the whole ecosystem and your farm," said Dag Falck, organic program manager, Nature's Path. "After you've demonstrated and documented to your certifier that you've done these steps, if they are not adequate to control the problem, then only are you allowed to use things from the National List."

According to Falck, many organic farmers don't even consider using synthetic substances from the National List. "They say, 'that's not how I do things,'" he said.

For many consumers pesticide residues on food are a big concern and organic foods have been shown to contain far less pesticide residues than conventional foods. Benbrook, who has done extensive work on pesticide residues in organic foods, said: "When you compare organic versus conventional food, it is absolutely inarguable that organic food reduces dietary exposure to pesticides by 98 percent."