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Arkansas Fruit, Vegetable and Nut Update

What is the “Dirty Dozen” list and should you be worried about it?

by Amanda McWhirt - March 30, 2019

What is the "Dirty Dozen" list?    Let talk about it and how it is calculated!


  • Dr. Amanda McWhirt, Horticulture Fruit and Vegetable Extension Specialist
  • Dr. Jackie Lee, Horticulture Integrated Pest Management Extension Specialist
  • Ples Spradley, Pesticide Safety Extension Specialist

Recently the annual publication of the 12 “dirtiest” produce items was released. The publication claims to list produce items with high numbers of pesticide residues.  This list makes headlines each year and worries consumers and farmers alike. Consumers worry that their favorite fruit or vegetable will wind up on the list and farmers worry that their key crops might get vilified as being “dirty”.

So what is the deal with the dirty dozen list?

Let talk about it and how it is calculated!

First, what is a pesticide?

Pesticides are any number of fungicides (kills fungal diseases), insecticides (kills insects), and herbicides (kills weeds), that are used to combat pests in order to produce crops.

Pesticides tend to have a bad name due to the image that, well, they are designed to kill things! Pesticides should be used with caution, and the label (directions for use) should be read thoroughly before use and then followed exactly. Some pesticides are ‘restricted use’ meaning you have to undergo special training and get a license to use them. This is usually reserved for pesticides that require greater caution when applying.

Historically, pesticides have gotten safer over time and we now use lower application rates.

This is because we have moved from ‘broad spectrum’ to ‘very specific’ modes of action. A mode of action is just the means by which the pesticides kills the target disease, insect or weed. In the past we used pesticides that would kill a broad range of organisms, now we use more targeted pesticides that are more specific to a narrow range of types of organisms1. Newer pesticides are also applied at lower rates than many of their predecessors. No longer do we talk about application rates of gallons or lbs. per acre, now ounces or grams per acre are more common.  An application rate of 1 ounce per acre, amounts to about 1 shot glass of liquid over the area of a football field.

All pesticides require approval before being released, sold and used by farmers.

The U.S. Environmental Protection Agency (U.S. EPA) regulates pesticides, and has a rigorous process that requires the product demonstrate no risk to human health if used correctly. All pesticides must go through a registration process requiring a review of data on the safety of the product, except those that are 25(b) exempt, which include many pesticides used in organic agriculture. This data is used to construct pesticide labels which anyone who uses them must legally follow. The label is the law. Some products will not make it through the stringent review process, if they are found unsafe.

Safety data collected includes2:

  1. Evaluating if the product can cause harm to humans and under what circumstances (i.e. is it toxic to humans).
  2. Evaluating the dose, or amount, that can cause harm.
  3. Evaluating the exposure (timing and frequency) that may cause harm (i.e. how often a produce item is eaten for example would determine exposure).
  4. Evaluating the overall risk, combined information about the dose, exposure and conditions under which harm may occur.

The EPA then sets tolerance levels of residues for the pesticide on food 3,4. The tolerance level is the amount of residue that is allowed and that has been determined to not cause harm to human health based on how much exposure a person is likely to have. This process is true for synthetic pesticides. For some organically approved pesticides which are naturally derived, no tolerance level is set5.

Are there pesticides in organic produce?

It is important to realize that pesticides both naturally and synthetically derived are used in organic agriculture. Just because agricultural products are organically certified does not mean that they are “pesticide free”. Organic certification instead refers to a set of principles that govern how the food is grown. In the US these rules are governed by the National Organic Program (NOP)6.

The next step is ensuring that the food we eat has pesticide residue levels below the tolerances set by the EPA. The United States Department of Agriculture (USDA) is in charge of regularly and randomly testing food at multiple locations across the country to check for pesticides residues and make sure that produce is in compliance with the tolerance levels set7. Organic produce also goes through a similar process and is tested for pesticide residues to monitor for compliance with the NOP rules8,9.

Pesticides: amount and type and why they matter

The thing to remember is that what they are looking for is the amount and type of pesticide that is on the product. This amount of residue of a given pesticide is key to determining if the produce is safe.

Why do we care about the amount of pesticides?

Because the amount of the pesticide, or dose, is in large part what determines if a given pesticide will have any impact on its target or on human health.

Dose is easy to understand if you think about aspirin as an example. A small amount of aspirin might be good for you, but a large dose can be deadly. With pesticides tolerances, the amount of pesticide necessary to cause harm to human health is established and then residue tolerance levels are generally set 10 to 1,000 times lower than the amount that produced no adverse effects during testing.

USDA’s testing of pesticide residues show that annually 99% of sampled products have residues below EPA tolerances on average10. In their most recent report from 2017, 58% of produce sampled had no detectable residue and a remaining 39.7% had residues but at amounts below established tolerances 11.

What about “The Dirty dozen”?

The “The Dirty Dozen” is published each year by the Environmental Working Group (EWG). They use the data collected by the USDA’s pesticide residue monitoring program 12 and report the average number of types of pesticides found on a given product. They deem produce that has residue from more types of pesticides “dirty” and produce with residues from fewer types of pesticides “clean”.

This list doesn’t tell us anything about how much of any of the pesticides are found on the produce or how much risk any of the residues carry!

So according to the EWG system if 10 pesticides are found at 1,000 times lower the tolerance limit set by EPA, that fruit gets ranked as “dirty” while, another produce item that has only one pesticide residue at a slightly higher 100 times lower the tolerance limit gets ranked as clean.

Overall the amount of residue on our food is very small, and presents very low risk based on the amount present and the amount of fruits and vegetables we eat on a daily basis.  

Calculate pesticide residue

Want to know how much of a given fruit you would have to eat in order to be at risk? Check out the 
» Pesticide residue calculator.

Example of pesticide calculation:

A grown women would need to eat 454 servings of strawberries in one day before she might be at risk due to any pesticides residues on the fruit.

(This is based on the highest pesticide residues recorded for strawberries and not on the pesticides residues found on average.) 

“The Dirty Dozen” list isn’t an accurate representation of the risk to our health from eating fruits and vegetables.

The risk of not eating fruits and vegetables is much more of a concern to our health than the likelihood of consuming trace amounts of pesticide residue. This is concerning since most of us already don’t e at enough fruits and vegetables! 13

This misleading information creates anxiety for all consumers!

We all want to buy produce that is healthy and safe for ourselves and our families.

The reality is, is that our food supply is monitored and that both conventional and organic farmers do their best to ensure that our food supply is safe. Growers are trained and know how to comply with the rules on pesticide labels to ensure that pesticides are used safely in a way that does not put them or the consumer at risk.

What is the best way to ensure you have access to high quality and safe produce?

Get to know your local farmers!

Check out the list of local farms in Arkansas.

Ask your local farmer questions and learn about their practices. Good farmers are happy to have a conversation about how they grow the food that feeds our communities and their families. But it is on us to be informed consumers and make sure we are asking informed questions!

If you want organic produce ask your local farmer for it! But also know that growing food ain’t easy, and organic production requires more labor and more expensive inputs which means it costs more to grow fruits and vegetables using organic practices.

Conventional growers and organic growers alike do their jobs because they love growing things and feeding people. Hopefully this post will help prepare you to ask informed questions and start conversations about how food is grown!

Looking forward to a season of bounty and nourishment in 2019 across Arkansas.








7 Pesticide Data Program (PDP)

8 Organic Periodic Residue Testing

9 Organic Residue Testing,

10 The Pesticide Data Program, Factsheet





Pesticide Residue Calculator: