“What Agribusiness Doesn’t Want You to Know”

One of the arguments used by native plant advocates to defend the use of pesticides to eradicate non-native plants and trees is that this use is trivial in comparison to the volume of pesticides used by agriculture.  It’s not an argument that makes sense to us.  In fact, the opposite seems a stronger argument.  In other words, if it is necessary to use pesticides to produce our food, all the more reason to avoid the use of pesticides for other purposes, because the harm done by pesticides is cumulative.  Humans and other animals accumulate pesticides and other toxic substances in our bodies throughout our lifetimes so the fewer sources of toxic contamination, the better.

However, as we learn more about how pesticides are used by agriculture and how harmful pesticides are to us and other animals, the more we question the underlying premise.  That is, we wonder if it really is necessary to use pesticides to produce our food.  We have researched this question and we are reporting to our readers a brief history of pesticide use by agriculture, the consequences of this use, and finally, the growing evidence that present levels of pesticide use by agriculture isn’t necessary or justified.

The history of pesticide use by agriculture

The use of synthetic pesticides by agriculture began after World War II as a result of the development of new chemicals and the industry that produced them during the war.  Prior to WW II, farmers generally purchased raw chemicals to formulate primitive pesticides because ready-to-use pesticides were not available.  Here are some of the statistical trends that describe the use of pesticides by agriculture: (1)

  • Three-fourths of all pesticide use in the U.S. is by agriculture.
  • Pesticide use has been consistent at 2.6 to 2.7 pounds per acre of cropland per year for the past 25 years.
  • The volume of synthetic herbicide use has increased steadily since 1945, but the volume of insecticide use has declined after the 1980s as new low-dose products have been developed.
  • Fruits/nuts lead all other crops in terms of pesticide applications, with about 45 pounds of active ingredient per acre grown.  Vegetables receive about half that rate, but the rate nearly doubled from 13.4 to 23.7 pounds per acre from 1988-89 to 1996-97.

The expenditures for pesticides by agriculture are another way to understand the increased use of pesticides and their importance to both the agricultural industry and the chemical industry:  Farm expenditures on pesticides have increased from $296 million in 1929-31 to about $8.5 billion in 1995-97 in constant dollars. These are the factors that account for increased expenditures over seven decades:  (1)

  • The amount of active ingredient in pesticides usage increased during that period three fold (from 230 to 782 million pounds).
  • The replacement of low cost pesticides such as sulfur and petroleum by more expensive formulated pesticides.
  • From 1974-76 to 1995-97, the average expenditure per pound of active ingredient nearly doubled.
  • The average expenditure per capita for agricultural pesticides was reported as $32.10 in 2003.  That is, for every American, $32.10 was spent on pesticides for agriculture per year.

How does America’s pesticide usage compare to the rest of the world? (2)

  • World-wide expenditures on pesticides were $39.443 billion in 2007.  The United States bought one-third of all of the pesticides sold in the world in 2007.
  • The U.S. used 25% of all herbicides and 22% of all pesticides used in the world in 2007.

Changes in farming practices in the United States

Cornfield.  Creative Commons
Cornfield. Creative Commons

Farming in the United States has changed since World War II.  There are fewer farms and they are much larger than they were in the past.  Most farming is no longer done by the owner of the land.  This separation of farming and ownership has destroyed farming communities.  We no longer find farmers congregating in local cafes swapping tips at 5 am.  It has become an impersonal industry. (3)


Farming practices have changed to accommodate the industrial model.  Farms now grow only one or two crops which substantially reduces the traditional practice of crop rotation.  Animals are no longer found on farms because farming and raising livestock are now done separately.  Farms now specialize.

Increased pesticide use is both cause and effect of these changes in farming practices.  The drop in crop prices which made small farms unprofitable also motivated pesticide use to reduce labor costs.  Pesticides were also a substitute for the crop rotations which reduced insect populations by disrupting the relationship between predator and host.  Pesticides also compensated for the weed-suppressing effects of alfalfa grown to feed livestock now gone from the farm.  The loss of animal manure on the farm required the substitution of chemical fertilizers. The manure which had been useful in the past is now a waste product that pollutes water from run-off from industrial-size feed lots.  Separating farming from land ownership meant those using synthetic chemicals were no longer poisoning their own land and suffering the long-term consequences of their choices.

Traditional farming methods are equally effective and do less damage to the environment

The agriculture and chemical industries have been successful in convincing the public that the use of pesticides and associated farming methods were necessary to produce the food we need at the prices we are willing to pay.  This fiction has thus far sustained an industry that is clearly damaging the environment and exposing the public to environmental pollution.  There is growing evidence that traditional farming methods are equally effective and do less damage to the environment.

The results of a large-scale, long-term study comparing traditional farming methods with industrial farming methods were recently published.  The study was conducted by the US Department of Agriculture, University of Minnesota, and University of Iowa on the research farm of the University of Iowa.  They divided the research acres into three sectors and used three different farming methods to test and compare the efficacy of these methods:  (4)

  • Conventional method:  growing only corn and soybeans in a two-year rotation cycle, using synthetic fertilizers and pesticides.
  • Three-year rotation cycle, adding a crop of grains and clover.
  • Four-year rotation cycle, adding a crop of alfalfa plus livestock which was fed the alfalfa.

They conducted this test over a nine-year period from 2003-2011.  Here are the results of their study:

  • The longer rotations of more crops produced higher yields than conventional methods:  4% more corn and 9% more soybeans.  The longer rotations were also more profitable than conventional methods.
  • The longer rotations required less synthetic fertilizer than the conventional method.  The amount of fertilizer required by the longer rotations also decreased over time as the soil improved during the study.
  • The longer rotations reduced herbicide use by a whopping 88% with little increase in weediness.”  (4)
  • Longer rotations substitute labor for other inputs, but without reducing profitability.

Why aren’t traditional farming methods adopted?

As stunning as this information is, it is actually not new:  “In 1989, the National Research Council investigated alternative agricultural operations such as these and reported that U.S. farming could be shifted to more natural forms without losses to yields or profits, without significantly higher food prices, and with significant gains in health and environmental protection.”  (3) 

The Union of Concerned Scientists explains why the public is unaware of the superiority of traditional farming methods in their article about the new study done at the University of Iowa.  They tell us that the Economic Research Service of the US Department of Agriculture reports that 53% of all food and agriculture research is conducted by the private sector.  Clearly the agriculture and chemical industries would not fund a study that might conclude that conventional farming methods are harmful and/or uneconomical.  So, the availability of funding for such studies is limited.  (4)

In the event that such a study is conducted, what are the chances that it will be published?  The study done at the University of Iowa was rejected for publication by the journals Science and the Proceedings of the National Academy of Sciences.  It was finally accepted by PLOS One which is solely an on-line publication.  (5)

Finally, in the event that a farmer learns that traditional farming methods are less harmful to the environment and equally productive, what are the chances that he will adopt those methods?  The chances are small because the farmer probably does not own the land and is therefore unconcerned about polluting it and there is no cost to the farmer associated with polluting the environment. (5)

Pesticides are a public health risk whether they are used in agriculture or in our public parks.  In both cases, the good news is that it isn’t necessary to use pesticides.  If the public wants to reduce the public health risks of pesticide use, they will have to speak up.  Those who use pesticides are not going to stop using them unless they are forced to do so. 


(1)    Center for Integrated Pest Management, North Carolina State University, “Pesticide usage in the United States:  Trends during the 20th Century,” February 2003.  Available here.

(2)    Environmental Protection Agency, “Pesticide Industry Sales and Usage. 2006 and 2007 Market Estimates.” Available here.

(3)    Sandra Steingraber, Living Downstream, Addison-Wesley, 1997

(4)    Karen Stillerman, Union of Concerned Scientists, “Crop Rotation Generates Profits without Pollution (or, What Agribusiness Doesn’t Want You to Know,” October 11, 2012.  Available here.

(5)    Mark Bittman, “A Simple Fix for Farming,” New York Times, October 19, 2012.  Available here.

Why are we poisoning ourselves?

Americans banned DDT in 1972 and PCBs a few years later. We pat ourselves on the back for banning these and other toxic chemicals, but should we? Recent research suggests that though they were banned forty years ago, they are still making us sick.

Although these chemicals were banned, the chemical industry continues to churn out new products about which we know little. Will we find out decades later that these new chemicals are just as likely to poison us as their predecessors? The history of their predecessors suggests that is a likely outcome.

Living with the consequences of our folly

The National Research Council recently published a report (1) that informed us that at least 126,000 sites throughout the country have contaminated groundwater that requires remediation. About 10% of those sites are considered “complex” which is a euphemism for the fact that the technology required to clean them up does not presently exist, meaning that restoration is unlikely to be achieved in the next 50 to 100 years. The report estimates the cost of cleaning up these sites will be from $110 billion to $127 billion. However, the report also acknowledges that both the estimate of the number of sites and the cost of the clean up are probably underestimates.

What are the consequences of living with toxic chemicals? Researchers at Brown University tested the blood of over 3,000 women between the ages of 16-49 for levels of mercury, lead, and PCBs. These three chemicals are known to harm brain development of fetuses and babies. The sample was designed to represent the national population of 134.4 million women of childbearing age. Here’s what they found:

  • “Nearly 23 percent of American women of childbearing age met or exceeded the median blood levels for all three chemical pollutants.” (2)
  • “All but 17.3 percent of the women aged 16 to 49 were at or above the median blood level for one or more of these chemicals, which are passed to fetuses through the placenta and to babies through breast milk.” (2)
  • “As women grew older, their risk of exceeding the median blood level in two or more of these pollutants grew exponentially to the point where women aged 30 to 39 had 12 times greater risk and women aged 40-49 [born before these chemicals were banned] had a risk 30 times greater than those women aged 16 to 19.” (2)
  • “Fish and alcohol consumption also raised the risk of having higher blood levels. Women who ate fish more than once a week during the prior 30 days had 4.5 times the risk of exceeding the median in two or more of these pollutants.” (2)
The body burden of multiple pollutants
The body burden of multiple pollutants

While these findings are horrifying, they pale in comparison to the stunning finding that “One risk factor significantly reduced a woman’s risk of having elevated blood levels of the pollutants, but it was not good news: breastfeeding. Women who had breastfed at least one child for at least a month sometime in their lives had about half the risk of exceeding the media blood level for two or more pollutants. In other words, …women pass the pollutants that have accumulated in their bodies to their infants.” (2)

This particular study emphasizes the consequences of these pollutants for the children of the women who were tested. What about the women themselves? Surely these pollutants are also affecting their health and well-being. We turn to an outstanding book—Living Downstream– by an ecologist and cancer survivor (so far) for an answer to this question.(3)

First we must acknowledge how little we know about the connection between chemical pollution and its consequences to our health. The damage being done to our bodies by pollutants is not immediate nor is our exposure usually quantifiable which makes cause and effect very difficult to prove. Circumstantial evidence of the connection is therefore easily dismissed as anecdotal: women born in the United States between 1948 and 1958 had almost three times the rates of breast cancer in 1997 than their great-grandmothers did when they were the same age. Coincidentally, pesticide use in the United States had doubled between 1952 and 1997. (3, page 13)

Ironically, although DDT and PCBs were banned forty years ago, the connection between breast cancer and these pesticides was not discovered until after they were banned. The first study was conducted 4 years after DDT was banned on only 14 women with breast cancer. Significantly higher levels of DDT and PCBs were found in their tumors than in the surrounding healthy tissues. It took another 17 years to replicate that study on a statistically significant number of women: 14,200 women in New York City who had mammograms. The 58 women in that sample who were diagnosed with breast cancer had higher levels of DDT and PCB in their blood than women without breast cancer. (3)

It took nearly 50 years to prove that women with breast cancer have higher levels of DDT and PCB in their bodies than women without breast cancer. How long will it take us to learn what damage we are doing to ourselves with the pesticides that we are using now?

We aren’t testing for chemical pollution

Bacterial pollution at Pine Lake, San Francisco.  February 2012
Bacterial pollution at Pine Lake, San Francisco. February 2012. Courtesy Save Sutro

In San Francisco, the Department of Public Health tests the water bodies in the city for bacteria. In February 2012 they closed Pine Lake to the public because of bacterial levels. This incident prompted us to ask about San Francisco’s testing of water bodies. We learned that testing for bacteria is the ONLY test conducted in San Francisco. The watershed of Twin Peaks and Glen Canyon into Islais Creek was sprayed with pesticides over 30 times in 2011 by the Natural Areas Program, yet the water in the creek was not tested for pesticide levels. Islais Creek flows into the bay.

The need for more testing of water bodies was recently recognized by the European Science Foundation. (4) They conducted a poll of 10,000 citizens from 10 European countries which found that pollution is the top concern of the public among all concerns regarding the marine environment.

The public has good reason for their concern. There are presently about 30,000 chemicals available on the European market with production volume exceeding one ton per year. The volume of these chemicals entering rivers, streams, estuaries, and seas is increasing and potentially damaging marine organisms, ecosystems, and processes. Yet the testing of waters for these chemicals lags far behind the increasing number of chemicals being introduced to the environment.

We are on a pesticide treadmill

The tests required to put new chemicals on the market are minimal. The testing of pollution levels in the environment is also minimal. Yet, we continually introduce new pesticides about which we know little. Why? We speculate about the motivation for introducing new pesticides into the environment:

  • As the patents on pesticides expire, the manufacturers must introduce new pesticides in order to maintain their profit margins.
  • The longer a pesticide is in use, the more likely its target is to build up a resistance to it. Hundreds of weeds are resistant to available herbicides. Hundreds of insects are resistant to available insecticides.
  • The less the public knows about a pesticide, the less likely they are to be afraid of it and the less likely they are to object to its use..

Why is this issue relevant to Million Trees?

Our regular readers might wonder what this has to do with the mission of Million Trees to inform the public of the destruction of non-native trees for the purpose of creating native plant gardens. The connection is that the use of pesticides by these projects is skyrocketing as the war on non-native plants escalates.

Volume of pesticide use by San Francisco's "Natural Areas Program."  Courtesy San Francisco Forest Alliance
Volume of pesticide use by San Francisco’s “Natural Areas Program.” Courtesy San Francisco Forest Alliance

Those who work for these projects and those who support them defend their use of pesticides in our public parks by telling us they are following the rules, and the rules guarantee no harm will be done by the pesticides. What they don’t seem to understand is that many of the pesticides—and other chemicals—that we now know are harmful to us and the animals that we live with, were legal when they were used. They were legal because we did not know yet that they were harmful.

It took decades for us to understand that the pesticides we were using were harmful. We see no reason to believe that the pesticides we are using now will not also prove to be harmful. By the time we learned how harmful they are, a great deal of damage had already been done. And although many were banned decades ago, they persist in the environment and in our bodies. Therefore, we object to the frivolous use of pesticides in our public parks. Using pesticides for the purpose of killing vegetation solely because it is non-native is irresponsible, given the potential damage they can do to humans and wildlife.


(1) National Academy of Sciences, “Clean-up of some U.S. contaminated groundwater sites unlikely for decades,” November 8, 2012

(2) Marcella Remer Thompson, Kim Boekelheide, “Multiple environmental chemical exposures to lead, mercury, and polychlorinated biphenyls among child-bearing-aged women: Body burden and risk factors,” Elsevier, November 16, 2012

(3) Sandra Steingraber, Living Downstream, Addison-Wesley, 1997

(4) European Science Foundation, “Chemical pollution in Europe’s Seas: The monitoring must catch up with the science,” March 21, 2012