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Ask Dr. Gourmet

Does washing fruit and vegetables remove the pesticides?

I am concerned about pesticides on foods. How does one avoid the "dirty dozen" and protect infants and children, while still eating a balanced diet?

Do any safe cleansing agents get rid of pesticides on food? What solid research indicates that the "washes" work?

Dr. Gourmet Says...

Cut Celery

This is a challenging question and I will admit that over the last few years I have personally been moving more and more toward consuming organic products. There is clear evidence that consuming organic products leads to a decrease in pesticide consumption.

One great study was published in 2006 (Environ Health Perspect 2006;114:260-263) with researchers measuring pesticide exposure in 23 children by looking for pesticide metabolites in their urine.

They put the kids on a diet that substituted most of their conventional diets with organic food items and the metabolites of two pesticides, malathion and chlorpyrifos, decreased to undetectable levels almost immediately. They kept the kids on the diet for 15 days and the urine remained clear during that time, but the urinary pesticide metabolites returned after the introduction of conventional diets.

Certainly this sort of research is worrisome. We don't have the most perfect data on how much pesticide consumption is safe (if any at all). While this statement is controversial and folks on both sides of this issue will argue about the risks, I have come to believe more and more that this is worth taking the time to choose organic, especially organic produce. This is less of a challenge today but it is clearly more expensive and that presents a problem for many folks.

The "dirty dozen" that you refer to came from a study by the Environmental Working Group. This non-profit organization looked at data from the USDA about residual pesticides in produce. These are "the 12 fruits and vegetables that consistently have the highest levels of pesticides" and their recommendation is to avoid them. Here's the best to worst from their study:

1 (Best; lowest level of pesticides) - Onions
2 - Avocado
3 - Sweet Corn (Frozen)
4 - Pineapples
5 - Mango (Imported)
6 - Sweet Peas (Frozen)
7 - Asparagus
8 - Kiwi Fruit
9 - Cabbage
10 - Eggplant
11 - Cantaloupe (Domestic)
12 - Watermelon
13 - Grapefruit
14 - Sweet Potatoes
15 - Honeydew Melon
16 - Plums (Domestic)
17 - Cranberries
18 - Winter Squash
19 - Broccoli
20 - Bananas
21 - Tomatoes
22 - Cauliflower
23 - Cucumbers (Domestic)
24 - Cantaloupe (Imported)
25 - Grapes (Domestic)
26 - Oranges
27 - Red Raspberries
28 - Hot Peppers
29 - Green Beans (Imported)
30 - Cucumbers (Imported)
31 - Summer Squash
32 - Plums (Imported)
33 - Pears
34 - Green Beans (Domestic)
35 - Carrots
36 - Blueberries (Imported)
37 - Lettuce
38 - Grapes (Imported)
39 - Potatoes
40 - Cherries
41 - Kale / Collard Greens
42 - Spinach
43 - Sweet Bell Peppers
44 - Nectarines
45 - Blueberries (Domestic)
46 - Apples
47 - Strawberries
48 - Peaches
49 (Worst; highest level of pesticides) - Celery

Does washing work? It appears so. In an article published in 1996 researchers at the Southwest Research Institute reported on their experience in washing various produce items. For grapes, strawberries, green beans and leafy vegetables they swirled the items in a dilute solution of Palmolive dish detergent and water at room temperature for 5 to 10 seconds. They then rinsed with warm water. The solution was 1 teaspoon of the Palmolive in a gallon of water.

For other fruits and vegetables they used a soft brush to scrub the food with the detergent solution for about 5 to 10 seconds and then rinsed with warm water. They didn't include such items as lettuces and citrus fruits, because their analysis showed that most of the pesticides were in the outer leaves or the rinds, which were not eaten. Washing, they found, removed about 75% of the pesticides.

Does cleaning help? We don't have long term information about the effects of pesticides in produce, but you can certainly reduce exposure to your kids by choosing organic when you can and washing your conventional fruits and veggies.

Thanks for writing,

Timothy S. Harlan, MD, FACP, CCMS
Dr. Gourmet