Monday, June 1, 2015

Fact Check: Agricultural pesticide use peaked 30 years ago

There’s been lots of discussion, assertion, and misinformation in the Hawai`i GMO battles in recent years about what’s been happening with U.S. agricultural pesticide use. 

That's amid critical assertions of "more and more" pesticide use, and hyperbolic claims that tons and tons of pesticides are being dumped on the land. The real story is more nuanced.

The U.S. Department of Agriculture last year did a thorough review of the subject, in a report called “Pesticide Use in U.S. Agriculture: 21 Selected Crops, 1960-2008.”
“The examination of pesticide use trends is critical for informed pesticide policy debate and science-based decisions,” the report says.

Some key points from the study:

  • Pesticide use in American agriculture peaked more than 30 years ago, and on average has been dropping since.
  • Agriculture is using a lot more weed killer than it used to, and far less insecticide.
  • It is using chemicals that are far safer and yet more effective than before.
  • Corn farming gets hit with being a big pesticide user, but that is partly because there are a lot of acres in corn. The crop uses pesticides more sparingly than cotton, fruit and vegetable farming.

Pesticide use in U.S. agriculture grew rapidly through the 1960s and 1970s, peaking in 1981 at 632 million pounds of active ingredient. (See our note on the whole active ingredient thing at the bottom of this article.)

And pestide use has been going down since then, to 516 million pounds in 2008, the most recent year with complete numbers.That’s a 19 percent drop in pesticide use. The drop in total acreage in U.S. agriculture during the last 30 years was about 9 percent. 

If you're thinking that agricultural use of pesticides is dominant, think again. It represents less than half of all U.S. pesticide sales, which according to the EPA exceed 1.1 billion pounds annually. If you include wood preservatives, specialty biocides, and chlorine/hypochlorites, the amount climbs to more than 5 billion pounds.

While the overall amount of active ingredient in agricultural pesticides has been slowly decreasing, the relative use in different classes of pesticides has changed dramatically. There has been a wild drop in the amount of insecticide, but a big increase in the amount of herbicide. 

“As a result of increased adoption of Bt corn by U.S. farmers for insect control, insecticide use declined steadily from 0.24 pound per planted acre in 1996 to 0.15 pound by 2000 and 0.05 pound in 2008. Insecticides accounted for only 2 percent of total pesticide pounds applied to corn in 2008,” the report says (USDA report page 65.)

That change is a key reason overall use has dropped. Insecticides used to be the largest category of pesticides in agriculture.

“Insecticides accounted for 58 percent of pounds applied in 1960, but only 6 percent in 2008. On the other hand, herbicides accounted for 18 percent of the pounds applied in 1960 but 76 percent by 2008,” the report says.

Fungicides stayed relatively even at 7 percent, and “Other pesticides—which include soil fumigants, desiccants, harvest aids, and plant growth regulators—generally accounted for 5-11 percent of total pesticide use from 1960 to 1992, increased to 17 percent of use in 2002, and then declined to 13 percent in 2008.”

It is also clear that the individual pesticides have changed, since “the EPA determined that some pesticides, such as DDT, aldrin, dieldrin, chlordane, and heptachlor, posed unreasonable risks and their registrations were subsequently canceled.”

Which crop uses the most total pesticides? Corn used 39 percent in 2008. Soy used 22 percent. Potatoes 10 percent. Cotton 7 percent. And wheat less than 5 percent.

Those are totals and not per-acre numbers. The ranking  roughly correlates with acreage. The EPA reports that, as of 2011, the largest crop by acreage was corn (84 million acres), followed by soy (73.8), hay (55.7) , wheat (45.7), cotton (9.5), sorghum (3.9)  and rice (2.6.)

The National Potato Council reports that potatoes cover less than those crops—about 1 million acres. Pesticides are also used on dozens of other crops. Apples, oranges, peanuts, sugar cane, tomatoes, grapes and many others. 

“Corn producers apply more pounds of pesticide than any other crop farmers, but use pesticides much less intensively than cotton, fruit, and vegetable producers. For example, potato producers use about 50 pounds per planted acre, versus 2.4 pounds per corn acre,” the report says (Page 62.) 

The uses are also different. Corn uses herbicides more, and potatoes use more fungicides than herbicides or insecticides.

Is research improving the levels of safety? The report argues that it is. The most hazardous compounds have been banned. New formulations have allowed the reduction in usage from pounds per acre to ounces or fractions of an ounce. Many newer insecticides are used at far lower rates than previous chemistries, the report says.

And the EPA has ramped up its requirements for toxicity and human health risk studies.

But what about the dramatic rise in herbicides while insecticides, fungicides and other agriculture chemical remain comparatively low? The report says it is largely a price-driven phenomenon.

“As several new effective products were introduced, the cost of pesticides fell relative to other pest control practices over the period and encouraged substitution of pesticides (particularly herbicides) for labor, fuel, and machinery use in pest control,” the USDA report says.

That means farming got cheaper as a result. In the mid-1960s, energy costs, wages and pesticide costs were about equal in terms of their cost to farmers. Today, pesticide costs are by far the lowest of those three for American farmers. (see USDA report Page 17.)

(Let’s make a side point here that in this report, the USDA actually calculates pesticide quantities in terms of amount of active ingredient. 

(In the same way that a cup of pure sugar is different from a cup of water with one teaspoon of sugar mixed in, a container of weed killer with 40% active ingredient is different from 2% active ingredient. 

(When someone talks about “tons of pesticides” without distinguishing active ingredient, it’s not particularly useful information. Could be tons of water, with a few ounces of active ingredient.  
Could be something else.)

© Jan TenBruggencate 2015


Unknown said...

This is a well written story that needs to be widely disseminated here in Hawaii to the general public and to policy makers.

This USDA report is a relatively unknown gem that has the data showing how much safer and better for the environment pesticides have become over the past 40 years.

The box figure 4.1 on page 28 of the report shows the decline in toxicity, application rate and persistence of pesticides over 4 decades, and they note the contribution of glyphosate and GM crops in achieving this - a great graph for those who prefer a quick visual summary.

For some, the universe would have to invert itself before acknowledging evidence that increased use of glyphosate and GM crops is linked with overall safer and less persistent pesticides, but here it is.

Dave Smith said...

I know there has to be some lag between data and analysis, but six years?

Anonymous said...

The main reason why there has been improvement on this front is the fight against environmentally destructive farming, and industrial practices. These groups have consisted of normal mostly unpaid citizens, over qualified/underpaid non profit lawyers, and volunteers who have fought to clean up their groundwater, air, soil and children's future. Lets not act like the big boys are complicit in trying to clean up their act, we have had to fight them any way possible and against staggering odds, lopsided gov. representation, lobby firms, hired big shot legal firms, they went kicking and screaming (still are) etc.... Its a slow fight to keep the future from inheriting our toxic legacy, ground water has already been poisoned from the pineapple, water or pineapple for some rich people... hmmmm. tough questions, but I respect all people on both sides, but not the companies... Their history is clear to anyone that can read.