GMOs, food and pesticides 101: No chemical “flood” and yields are rising

Has the growing of GMOs led to a “flood” of pesticide use as critics contend?

You see such claims rampant on advocacy sites. “Herbicide and Insecticide Use on GMO Crops Is Skyrocketing, and Rubber-Stamped Approvals Now Usher in Next-Gen GMOs,” screams a headline on natural product huckster Joseph Mercola’s eponymous website. Such statements are a staple during GMO labeling ballot initiatives–and they are effective. Who would want to embrace an innovation if it ended up doing more harm than good.

That’s just not what the data show. Moreover, the single minded obsession–focusing on pesticides as having the most environmental impact in modern agriculture misses the big picture and distracts from tackling far more serious ecological challenges.

Opposition by environmental groups to recent USDA approvals of new herbicide tolerant biotech crops underlines a strange aspect to the debates about how to lower the environmental impact of agriculture. Earlier this year, Food and Water Watch predictably came out againstMonsanto’s new glyphosate and dicamba tolerant soybeans, claiming that it would lead to more resistant weeds and massive problems with pesticide drift.

This approval follows that of 2,4-D tolerant soybeans and corn, billed as the next generation of herbicide-tolerant crops to tackle glyphosate (Roundup)-resistant weeds. Dicamba-tolerant soy and cotton are simply the latest example of USDA’s allegiance to the biotechnology industry and dependence upon chemical solutions. This continues the disturbing trend of more herbicide-tolerant crop approvals taking place under President Obama’s watch.

In 2014, the Environmental Working Group warned the nation that hundreds of thousands of American school children would newly be at risk to a toxic weed killer.

There are 5,532 American schools within 200 feet of farm fields that may soon be blanketed with massive amounts of a toxic defoliant linked to Parkinson’s disease, non-Hodgkin’s lymphoma and reproductive and immune system problems.

That’s the finding of a new EWG analysis that shows that hundreds of thousands of children across the country will be at risk of increased exposure to the harmful chemical compound 2,4-D if the Environmental Protection Agency approves a new weed killer mixture called “Enlist DuoTM” created by Dow AgroSciences (a wholly owned subsidiary of Dow Chemical Co.).

That apparently doesn’t worry the EPA. But if these rural schools were full of plants rather than children, the agency would be concerned.

(Andrew Kniss, Associate Professor, Weed Biology & Ecology at the University of Wyoming, took a look at the claims about drift for dicamba and 2,4-D and the risks to schoolchildren — they don’t really hold up.)

The big thing that stands out in the debate between advocates of technologically progressive agriculture and the opponents of technological agriculture is the persistence of the idea that the use of pesticides is still a major problem, if not the central environmental impact of agriculture, that needs to be addressed. This is unfortunate. It’s just not accurate. It’s a cul-de-sac in the discussion about how to improve the environmental footprint of agriculture. It’s a distraction from the addressing the major environmental impacts.

Curing the chemical hangover of the post-war era

The disconnect mostly comes from the chemical hangover from the unfortunate excesses of industry during the 1950s, 60s and into the 1970s. DDT, PCB’s, a raft of dangerous food colorings and additivespulled from the market, Love Canal and similar incidents left people with the unshakeable feeling that everything causes cancer and technological progress might be more trouble than it’s worth.  People have a much better handle on that dismal chapter of history than they have on the reforms and innovation that came after. With creation of the Environmental Protection Agency and the passage of the Clean Air and Water Acts, regulation has become much tighter. Meanwhile, scientists began working in earnest to create pesticides that were more effective, while making less impacts where they weren’t supposed to. Environmental watchdog groups have worked hard to make sure that they do.

There are other reasons for the disconnect. There is a notable lack of incentives for both environmental groups and agri-chemical companies to trumpet the progress that’s been made in lowering the toxicity and reducing the collateral damage of pesticides. Another source of disconnect is the way organic farming has been marketed or perceived, falsely, as pesticide free. Pesticides as an environmental impact are often played up by organic advocates and advertisers as a way of highlighting the alleged benefits of organic agriculture.

All of these threads have come together to make a widespread lack of understanding about how modern pesticides are much safer and less toxic than earlier generation chemicals. Many pesticides have been banned in recent decades and those that have been approved are much more targeted in the way that they work. Following the uproar over DDT (deserved or not), scientists have made degradibility a central priority, so today’s pesticides are far less persistent in the environment. We’ll get to all that, but let’s start by laying out the major impacts of agriculture.

Agriculture’s biggest impacts

The discrepancy between the actual environmental impact of pesticides versus how they are perceived was brought home last summer with the publication of “Leverage points for improving global food security and the environment” in the journal Science by a group of University of Minnesota scientists. What’s the sustainability picture?


The environmental impacts highlighted include water use and irrigation; nutrient leaching and eutrophication due to excess nitrogen and phosphorus; land use, especially tropical deforestation; and greenhouse gases, especially N2O but also carbon and methane. If you look at the research on the environmental impacts of food production by researchers like geophysicist Gidon Eshel of Bard College (Michael Pollan’s go-to source on these matters) you will find a similar set of concerns and the same absence of pesticides as an environmental concern.

When you really dig into the research on the hierarchy of ecological impacts, pesticides represent a drop in the sustainability bucket when compared to land use, water use, pollution and greenhouse gases. In fact, it may seem counter-intuitive but, pesticides can play a substantial role in mitigating the damage associated with many of those other factors. Pesticides allow for us to grow more food on less land, limit the wasting of fuel and water, and help curb erosion and run-off.

In conversations however, I continually find myself engaging people promoting practices that result in major compromises on land and water use, water pollution and greenhouse gases in exchange for the potential to decrease pesticide use. This is getting the calculations and priorities on environmental impacts exactly backwards.

What you should know about pesticide use in 2016

What’s changed about pesticide use since Silent Spring, Rachel Carson’s 1962 classic book that ignited people’s concerns about the environmental downsides of pesticides? It’s true that pesticides, when misused, still pose risks to farm workers, and a few pretty nasty pesticides are still in use. For instance, chlorpyrifos, an insecticide has been linked to developmental issues in the children of farm workers. Methyl bromide, a soil fumigant has been linked to ozone depletion and cancer risk for farm workers * These are important challenges, but their use is decreasing while the use of more targeted and less toxic chemicals steadily increases.

Chlorpyrifos is an organophosphate insecticide, perhaps the most problematic class of pesticides. Organophosphates are nerve agents, and the way they kill bugs also works on animals and humans. The good news is that the use of organophosphates has been steadily declining over the past three decades as this chart in Science shows.


In the last few years, agriculture expert and writer Steve Savage has done great work breaking down common misconceptions about pesticide use. In a post using the California grape industry as a typical example, he shows how the profile of pesticide use has dramatically improved over the years. Contrary to campaigns by environmental groups and anti-GMO activists that talk about a “flood” of “toxic pesticides” unleashed since the beginning of the biotech era, the data show usage shifting dramatically away from Category II (moderately toxic) and Class III (slightly toxic) towards Category IV (practically non-toxic) and the almost complete abandonment of Class I (highly toxic) pesticides.


This pattern is repeated across almost all grain, fruit and vegetable farming. In another post putting pesticide use into greater context, Savage shares two key charts.


The chart above underscores that today’s most prevalent pesticides are relatively benign from a human health perspective: more than 60% of the pesticides used in California are classified as Category IV (relatively non-toxic) and another 20% are Category III (slightly toxic).

Savage goes on to compare the amount of pesticides used in California in relation to the toxicity of substances that we popularly consider safe or even good for us.


Nearly all the pesticides used in California are less toxic than caffeine or aspirin, with only 3% by acreage more dangerous than your favorite morning pick-me-up or your favorite pain reliever. More than half are less toxic by weight than vitamin C.

What drives the perception disconnect?

Savage also lays out the interesting story about what has contributed to the reduction in pesticide use and what forces are in place conspiring to keep these achievements something of a public secret. It’s worth quoting at length.

  • The Environmental Movement: becoming visible after the publication of Rachel Carson’s “Silent Spring” in 1962, a broad coalition of NGOs, politicians and academics drove the awareness and impetus for the creation of regulatory bodies such as the EPA (est. 1970) which began to regulate pesticides. In a variety of ways these groups have continued to be an important voice that puts pressure on regulators to deal with additional issues as they arise through advances in the sciences of human and environmental toxicology. However, you won’t hear these groups talking about how much things have improved. They tend to focus on the next issue rather than on past progress, even if they could take some real credit along with the rest of the “team.”
  • The Major AgroChemical Companies: These players have been investing hundreds of billions of dollars over decades to discover, evaluate, and commercialize new pesticide options. Their search has been for products that work better, which are more selective, and which can meet ever more sophisticated health and environmental standards. Without this investment, between pest resistance development, new pests and regulatory constraints, farmers would never have been able to accomplish the sort of productivity gains that have been seen. These players are actually constrained by the EPA from talking about new products as being safer than the older ones. They also usually have a mixed portfolio of newer and older products. Besides, in an anti-business climate their messaging is typically ignored.
  • Government Regulators: If you step back and look at what agencies like the US EPA have accomplished over the decades, it is rather impressive. On the whole, the EPA has done its job in a way that is science-based and free from excessive political influence. As is probably the fate of any such regulator, the various “sides” on issues are all going to be unhappy with something about your decisions or bureaucratic procedures. Honestly, the EPA does not seem to have the skill or orientation for public promotion of what they have achieved (although this summary is pretty good). In any case the political Right tends to want to get rid of the agency, and the Progressive Left seems to think that they have all been “bought-off.” I have some direct experience with EPA staffers and a window on their process through friends who serve on advisory panels. This system isn’t perfect, but it deserves a great deal more respect than it gets.

Pesticide use commands inordinate attention from the general public because they are seen as “unknown” and “scary”. The fears play into the well known inability of humans to to distinguish harm from risk. Even the mere mention of the word “chemical” can touch off an extreme psychological and irrational reaction. Yet most fears are simple run of the mill chemophobia. Synthetic chemicals are automatically considered more harmful than natural chemicals, although synthetics are often specifically developed to be better targeted and less toxic. The general public tends to think just the opposite–the “natural fallacy”.

It’s the same reason we fear shark attacks more than slipping in the shower or driving when tipsy despite the fact that our bathrooms and drinking and driving are thousands of times more treacherous than swimming in the ocean. As consumers we are almost completely insulated from any serious health risks when it comes to pesticides. The residue levels in food, based on decades of empirical data, is mostly infinitesimal, and dropping.

Screen Shot 2015-02-01 at 4.28.55 PMChemophobia has been used as a major wedge among agriculture warriors, used as a political football in the culture war between organic and conventional agriculture. Pesticide use, while not absent from organic farming, is perceived as the most visible difference that sets organic apart. It’s a perceived sustainability advantage (but not really, in fact). When you dig below the surface at the organic impact of various farming types, however, organics fairs less well. On concerns like carbon, methane, nitrogen and phosphorus pollution, organic farming is less sustainable. Thus, much is made about synthetic pesticides, despite their relatively minor environmental impacts.

How biotech crops have impacted pesticide use

Insect resistant crops, corn and cotton that produces produce proteins toxic to pests, have been pivotal in reducing insecticide. While that impact is well documented, it’s less well known. Here’s the most recent USDA report on the issue:

Farmers generally use less insecticide when they plant Bt corn and Bt cotton. Corn insecticide use by both GE seed adopters and nonadopters has decreased—only 9 percent of all U.S. corn farmers used insecticides in 2010. Insecticide use on corn farms declined from 0.21 pound per planted acre in 1995 to 0.02 pound in 2010. This is consistent with the steady decline in European corn borer populations over the last decade that has been shown to be a direct result of Bt adoption.


Even farmers who didn’t adopt Bt corn benefited from the reduction in pests
Borrowing again from the infographic from Science, we can see how the use of soil applied insecticides plummeted as Bt corn planting became more widespread .


Here’s use in corn broken out by insecticide.


The decrease is due to the effectiveness of Bt crops as well as a virtuous cycle, notesGrist food and agriculture writer Nathanael Johnson:

When I started asking about environmental effects, several experts who take a critical view of GMOs pointed me to an entomologist at the University of Arizona named Bruce Tabashnik. Yet Tabashnik was surprisingly upbeat: So far, he said, insect-resistant plants have been a clear win for the environment. “Because of them, we’re running the pesticide treadmill in reverse,” he said.

The pesticide treadmill describes a problem that consistently occurs in agriculture. It goes like this: Eventually, insects evolve resistance to an insecticide, so the farmer starts using more sprays or something more toxic. But this can kill all the critters in the fields — not just the pests, but also the predators that eat the pests. Then the problem gets much worse. As time passes the farmer becomes more and more dependent on chemicals as the only means of pest control, using larger amounts, or more severe poisons, and getting less benefit.

But transgenic insect-resistant crops have turned this process around, Tabashnik says. These plants produce proteins from a widespread bacterium known as Bt (Bacillus thuringiensis) that only harm a narrow set of insects. Bt itself is widely used as an insecticide, mostly by organic farmers. Because the Bt-producing crops kill some key pests, farmers spray less insecticide to control those pests. This allows beneficial insects to survive. With more insect predators there’s less need for insecticides, and when farmers do spray, the insecticides work better.

The link between Bt crops and the decrease in insecticide use is unequivocal. The numbers on herbicide use are less dramatic and the picture less stark–until you dig deeper. Glyphosate use has increased and total pounds of herbicides are up a little or down a little depending on what data is cited. But the real story is the the most toxic herbicides  have fallen by the wayside.

Let’s take a look at the second and third most popular herbicides from the pre-biotech era. Prior to 1996, alachlor was the second most popular herbicide after atrazine. Alachlor is banned in Europe and strictly regulated in Australia. It presents some health risk to humans.


The third most heavily used herbicide prior to 1996 was cynazine, basically atrazine plus cynanide. it was an herbicide that caused birth defects in animals. It has disappeared from the market without a ban from the EPA.


So, the odd thing is that even though preservation of soil is a major goal of the Environmental Working Group and clean water is a major goal of Food and Water Watch, both groups put a lot of time and energy into opposing pesticides and biotech crops when biotech crops have helped to improve the profile and impact of pesticide use, while improving soil conservation. The role that glyphosate and other herbicide tolerant crops have played in the adoption of conservation tillage should be something both groups could get behind. Conservation tillage reduces erosion, water use, and fertilizer run-off. Those are all big ticket environmental impacts, made possible in many cases by an herbicide that with a lower toxicity than table salt, and applied fairly sparingly. Just between corn and soybeans, we are talking about 100-150 million acres of conservation tillage.


Pesticides in a world of trade offs

There is still room for improvement. Pesticides do get misused, especially in developing countries without strong regulations and little public spending on ag education and training. They can harm wildlife and pollinators. Farm workers need stronger protection.

But the single minded focus by many on pesticides ignores that we live in a world of trade offs and producing the most food on the least amount of land, with the least amount of water, the least amount of erosion, the least amount of fertilizer runoff, and the least amount of greenhouse gases is a larger, more important set of goals. Those goals can often best be advanced through smart use of some fairly non-toxic tools.

* Use of methyl bromide in the U.S. is currently only allowed in strawberry production under an “critical use” exemption to the Montreal Protocol on ozone depletion. That exemption ends in 2017.

-Written by Marc Brazeau in Genetic Literacy Project.  See article link here.  Marc Brazeau is an independent food and agricultural writer.  He blogs at Food and Farm Discussion Lab. Follow Marc on Twitter @realfoodorg.

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