Focus on Pesticides is a Distraction from Major Eco Impacts

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A quick note in my news feed highlighted a new data set from the World Banks that shows that while the US has one of the most productive agriculture sectors in the world, it also has some of the lowest rates of pesticide and fertilizer use. Good news. The author’s title, however, stuck me as unfortunate: World’s Model for Sustainability in Food Production. His write up was about pesticide and fertilizer use, and while high yields, with low pesticide and fertilizer rates are very commendable (and surprising to many), pesticide and fertilizer use is hardly the last word in sustainability in agriculture. And among the biggest impacts of agriculture: land use, water use, greenhouse gas emissions, water pollution; pesticides hardly rate. And yet…

One of the things that has really begun to stand out in the debate between advocates of technologically progressive agriculture and the critics 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.

Before getting into the details of our story, I’d like to take a quick look at the big picture by way of the raw trend in pesticide use in the US.

The USDA recently took a look last year at the use of pesticides since 1960. What they found is that use peaked in 1981 and has remained fairly steady with a small decline from 1981 to 2008.

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There are two important variables that aren’t caught in that graph. The first is that it doesn’t capture the improvements in the pesticides used. As we’ll see, the pesticides in use have become less toxic and more degradable over time. The second thing to keep in mind is that the population of the US in 1980 was 230 million, in 2008 it was 304 million. Yields have gone up dramatically. So, while use per acre has only modestly decreased since 1981, it has gone down dramatically both per capita and a per unit produced, while at the toxicity and biodegradability have improved. That’s not to say that use per acre isn’t important, but we should keep aware of other ways of assessing what’s going on to get a fuller sense of what has actually happened.

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 additives pulled 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 followed. 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 benefits of organic agriculture.

All of these threads have come together to create a widespread lack of understanding that 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, scientists have made degradibility a central priority, so today’s pesticides are far less persistent in the environment.

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.

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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.  There is nothing sustainable about pouring inputs into growing food that is destroyed by pests.

In conversations however, I continually find myself talking to people who would happily trade the need to use more land, more manure, more water, more fuel in exchange for decreasing pesticide use. In a world of trade offs, this is getting the calculations and priorities on environmental impacts exactly backwards.

What you should know about pesticide use in 2105

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.

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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.

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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.

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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.

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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.

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Chemophobia has been used as a major wedge among agriculture warriors, used as a political football in the culture war between organic and conventional agriculture. It’s understandable. While, deforestation in the Amazon or the deadzone in the Gulf of Mexico may be of greater consequence, they don’t rate compared to the spector of pesticide residues when we are at the supermarket trying to decide what to feed our kids.

Pesticide use, while not absent from organic farming, is perceived as the most visible difference that sets organic apart. Pesticides are permitted in organic, some of them quite nasty. It’s just synthetic pesticides that are prohibited. It’s a perceived sustainability advantage (but not really, in fact). When you dig below the surface at the environmental impact of various farming modes, however, organics fairs less well. On concerns like carbon, methane, nitrogen and phosphorus pollution, organic farming doesn’t have much to brag about. Thus, much is made about synthetic pesticides, despite their relatively minor environmental impacts.

A look at one type of trade off

A short blog post by Professor Andrew McGuire, an agronomist who focuses on helping farmers build healthy soils at Washington State University’s Center for Sustaining Agriculture & Natural Resources, highlights a clear case of where the judicious use of a pesticide, in this case an herbicide is the more ecologically sound decision compared to trying to avoid using the herbicide.

Last summer, I visited an organic farm in the area. The farmer showed me various parts of his operation, one of which was a field that he had planted to a species of perennial grass that produces an abundance of deep roots. We dug a hole and confirmed it; a dense fibrous root system had formed after two years of growth. The farmer’s goal in planting this grass was to build up the soil before vegetable production. When I talked to the farmer again this fall, he was trying to figure out how best to go from the grass to vegetables. There could be two options for doing this.
The first is to till the grass crop in order to kill it. This would most likely require disking the soil three times or plowing and then disking, to kill the grass and break up the sod that is turned up by the first tillage pass.

The other option would be to spray out the grass crop with an herbicide. One pass through the field and the grass would be killed completely if done right.

If the goal of growing the grass was to build up the soil, which is the best option? Tillage, we know from research, would break up the physical soil habitat built up over the two years, disturbing the microorganisms living there. It would also disturb or destroy larger soil fauna, such as earthworms. This physical destruction, combined with the flush of oxygen that comes with intensive tillage, would burn up much of the organic matter added by the grass. The tillage would also eliminate soil cover and leave the soil in a loose state that predisposes it to future compaction.

Spraying out the grass with an herbicide would leave the soil’s physical habitat intact. The root mass that we dug up last summer would be undisturbed and the surface would covered by the dead grass leaves, controlling wind erosion and reducing evaporation.

In terms of the goal of building soil, the second option is plainly better than the first. However, some may argue that herbicides are toxic, that they may be a detriment to soil organisms, or that they could pollute the environment. If we used the herbicide glyphosate (the active ingredient in Roundup) its toxicity is low compared to other herbicides (the EPA considers glyphosate to be non-carcinogenic and relatively low in toxicity). The toxicity concern is limited further because we are not spraying a crop that is going to be harvested and the chemical is not persistent in soils. Any detrimental effect to soil organisms would be minimal compared to the obvious effects of tillage. Glyphosate also has a small leaching potential.

For building soil, the choice is clear; spray out the crop.Last summer, I visited an organic farm in the area. The farmer showed me various parts of his operation, one of which was a field that he had planted to a species of perennial grass that produces an abundance of deep roots. We dug a hole and confirmed it; a dense fibrous root system had formed after two years of growth. The farmer’s goal in planting this grass was to build up the soil before vegetable production. When I talked to the farmer again this fall, he was trying to figure out how best to go from the grass to vegetables. There could be two options for doing this.

The first is to till the grass crop in order to kill it. This would most likely require disking the soil three times or plowing and then disking, to kill the grass and break up the sod that is turned up by the first tillage pass.

The other option would be to spray out the grass crop with an herbicide. One pass through the field and the grass would be killed completely if done right.

If the goal of growing the grass was to build up the soil, which is the best option? Tillage, we know from research, would break up the physical soil habitat built up over the two years, disturbing the microorganisms living there. It would also disturb or destroy larger soil fauna, such as earthworms. This physical destruction, combined with the flush of oxygen that comes with intensive tillage, would burn up much of the organic matter added by the grass. The tillage would also eliminate soil cover and leave the soil in a loose state that predisposes it to future compaction.

Spraying out the grass with an herbicide would leave the soil’s physical habitat intact. The root mass that we dug up last summer would be undisturbed and the surface would covered by the dead grass leaves, controlling wind erosion and reducing evaporation.

In terms of the goal of building soil, the second option is plainly better than the first. However, some may argue that herbicides are toxic, that they may be a detriment to soil organisms, or that they could pollute the environment. If we used the herbicide glyphosate (the active ingredient in Roundup) its toxicity is low compared to other herbicides (the EPA considers glyphosate to be non-carcinogenic and relatively low in toxicity). The toxicity concern is limited further because we are not spraying a crop that is going to be harvested and the chemical is not persistent in soils. Any detrimental effect to soil organisms would be minimal compared to the obvious effects of tillage. Glyphosate also has a small leaching potential.

For building soil, the choice is clear; spray out the crop.

Pesticides in a world of trade offs

There is still room for improvement in the use and toxicity profile of pesticides, especially in other countries. 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.

 

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