IPM and Pesticides: the elephant in the room

With some of the articles I’ve seen in the agricultural media so far this week on organic, GMO and conventional farming, I thought it was time to address one of the major elephants in the room when it comes to public perception of integrated pest management: the fact that IPM allows the use of pesticides.

Because pesticides are only one tool in the IPM toolbox, few of the articles I read about IPM cover them directly. In IPM, the use of pesticides is, or at least should be, directly related to the action threshold. For most pests of agricultural products, the threshold is a published number that lets the farmer know how many pests that should be present before any treatment begins. For a refresher on the steps for IPM, see my blog post from October on the different farming practices.

I’m not going to defend or deplore pesticides; they have a specific purpose, and they are effective when used properly. However, most of the articles I’ve read in recent months have taken one extreme side or the other: either pesticides are harmful to human health, so consumers should buy produce that’s pesticide-free; or there is absolutely nothing wrong with pesticides at all. I’m not going to argue the truth or fallacy in either of those arguments or make an emotional argument about whether pesticides are good or bad. Instead, I’m going to answer some questions about some of the technical aspects of pesticides.

  1. I’ve heard the term, “the label is the law.” What does that mean?The label on any pesticide—whether it’s an insecticide, fungicide, herbicide or the antibacterial spray you use on your counters—describes how the pesticide should be used. Those instructions include the crops or settings it can be used on, the amount that can be used, how it must be diluted, what clothing should be worn and how far from a body of water you must be.If there is a definitive time that a pesticide is bad, it is when the label is not followed. For instance, if you have thrips on your roses, you cannot use the same insecticide that you may use on your beans if the label does not say that you can use the product for roses. If you’re using RoundUp on weeds, you can use the diluted version in the spray bottle or dilute the concentrated version with the amount of water that it specifies, but NOT use the concentrated version directly on the weed. In fact, farmers who use a pesticide that is not labeled for a crop can face punitive action if FDA testing shows residues of an illegal pesticide on the crop.
  2. When food is sold in the supermarket, are any of the pesticides still on the food, and how do I know the food is safe to eat?This question highlights the main reason why IPM stories shy away from discussing the use of pesticides. The answer to the first question is “yes,” if pesticides have been used on the product (and yes, that includes organic food products, which can be sprayed with natural pesticides). The answer to the second question is a bit more complicated.EPA does extensive testing of pesticide residues on food and establishes levels of “tolerances,” or the amount of a pesticide that may remain in and on foods. The assumption is that in most cases, some of the pesticide will remain on the food. The EPA’s goal is to set a level of that amount that will pose the least amount of risk to adults and children. The EPA website has information about how it sets tolerances. The instructions for use on the pesticide label are written with those tolerances in mind. That is why anyone using a pesticide must abide by the label’s instructions for method of use, crops that it can be used on, and the amount that can be used in one application. If those instructions are not followed, the person may be endangering the consumer.

    While most of us want to see the word “safe” when referring to any human activity, especially eating, realistically speaking, there is always some level of risk in anything we do. Although many articles speak definitively about pesticides being “safe,” I am instead going to discuss pesticide residue testing in terms of the level of risk.

    The EPA uses four steps to assess human health risk for establishing tolerances: hazard identification, dose-response assessment, exposure assessment and risk characterization.

    In general, the EPA requires pesticide companies to evaluate their pesticides for a wide range of adverse effects, including eye and skin irritation, cancer, birth defects and neurological problems. Scientists use laboratory animals to evaluate health effects on humans. EPA also consults outside scientists and public literature to confirm evaluation reports.

    Next, scientists test the maximum dose that can be used before human health effects occur. Because some people may be more sensitive than others, EPA automatically builds in extra safety margins, and the Food Quality Protection Act requires EPA to add an extra 10-fold safety factor for infants and children. Pesticides are tested for short-term exposure, intermediate and long-term exposure to check for acute and chronic toxicity.

    The EPA places a value on the risk, called “risk characterization.” This value equates the amount of risk with the level of toxicity of the product and the likelihood of a person’s exposure to it. For instance, a product that will be used to control roaches and ants in a school building will have a different level of risk than a product that will kill fire ants in an outdoor area that can be quarantined, even thought the toxicity of the products may be the same, and the directions on the label will reflect that. The label on products that have a higher level of toxicity will specify a time period for re-entry into the treated area, based on the tested level of degradation of the chemicals. School IPM coordinators typically use low toxicity products like baits inside a school, so that children will not come into contact with them.

    More specific information about health risk assessment can be found on the EPA’s website.

    In short, a pesticide, used properly, is neither always safe nor always dangerous but does involve risk, just as many other human activities do.

  3. How do I know that the farmer who sells the food is following the label on the pesticide?If you are buying your food at a grocery store, producers go through sample testing by either USDA or FDA. If USDA screeners find residues that are above the EPA recommended amount, or if they find residues of a pesticide on a food product not included in the label of that pesticide, the product is prohibited from being sold.Produce sold on a family farm or a roadside stand is typically not inspected by USDA. Take the opportunity to talk to the farmer about how he or she protects the produce from insects or diseases if you’re concerned.
  4. If a farmer who uses IPM is still using pesticides, why is IPM considered better than conventional? There are still pesticides being used.The blunt answer to that question is that it depends on what you’re comfortable with. If a farmer is truly using IPM and is using pesticides, there are enough pests on his or her farm to meet the action threshold, and if he or she didn’t use pesticides, the crop would be damaged. Many of us would like to think that we could get the same gorgeous, unblemished produce at the store with no pesticides, but in many parts of the South, insects are abundant and very hungry. Being able to eat a tomato with no holes means that the farmer must keep pests away from it, which, even after other practices like crop rotation and cover crops, sometimes means that pesticides must be used. So don’t assume that anything labeled “organic” will be pesticide-free, either, as organic farmers must also sell “pretty” produce. A farmer who is practicing IPM will be using pesticides only when they are needed and not simply on a scheduled routine.Remember that any pesticide that is used legally (by the instructions on the label) has been tested for its effect on human health. There have been studies that have pointed to health effects of certain types of pesticides, such as organophosphates. The EPA is starting to re-review many of the pesticide classes again and welcomes public comment on those reviews. If you’re interested in commenting, or simply learning more about what goes into those reviews (there’s a lot of technical information in those posted research summaries), go to http://www.epa.gov/oppsrrd1/reregistration/.

    Sometimes there are local farms located in an area undisturbed by pests. While those farmers may not brand themselves as “certified” organic (certification costs money), they are worth seeking out. However, if you typically buy your produce from a farmers’ market or roadside stand, take the opportunity to talk to the vendor about how pests are managed on the farm. That conversation will at least give you more information about how your food is grown, and you’ll be making an informed choice when you make your purchase.

So now that you’ve read the long answer, the short answer is that you get to decide what you’re comfortable buying. Like anyone, I too prefer buying something that I know has not been sprayed. However, if that’s not an option, I trust that the systems that the U.S. has in place are protecting me to the best of their ability, and it’s my choice to buy the product or not.

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