Safe & Healthy: Does washing produce remove pesticides?

Educational messages say that consumers should wash fresh fruits and vegetables to help prevent illness, but is this really effective? Fresh produce can become contaminated in many ways and from both biological and chemical substances. During the growing phase, fruits and veggies may be contaminated by animals or microorganisms naturally in the soil, by substances applied to protect against pests, and as a result of poor hygiene among workers. After produce is harvested, contamination can increase, or may be decreased – depending on the contaminant. Garden Produce

The term ‘washing’ when applied to fresh fruits and vegetables is actually a misnomer. Fresh produce should be rinsed with clear running water, but not actually washed, prior to preparing or eating. Other tips for safe handling of fresh fruits and vegetables:

  • Choose produce that isn’t bruised or damaged, and make sure that pre-cut items—such as bags of lettuce or watermelon slices—are either refrigerated or on ice both in the store and at home.
  • Wait to rinse fresh produce until just before you use it. Gently remove garden soil, if necessary, and store in a storage bag so that unwashed produce does not contaminate ready-to-eat items.
  • Wash your hands for 20 seconds with warm water and soap before and after preparing fresh produce.
  • Cut away any damaged or bruised areas before preparing or eating.
  • Gently rinse produce by holding under running water and rubbing gently. There’s no need to use soap or a produce wash.
  • Wash produce before you peel it, so dirt and bacteria aren’t transferred from the knife onto the fruit or vegetable.
  • Use a clean vegetable brush to scrub firm produce, such as melons and cucumbers.
  • Dry produce with a clean cloth or paper towel to further reduce bacteria that may be present.
  • Throw away the outermost leaves of a head of lettuce or cabbage.

Most fresh produce, and all fresh produce after it is cut or peeled, should be stored in the refrigerator at 40°F or below.

Does rinsing fresh produce remove pesticides? Rinsing will help to remove soil and harmful bacteria that may be trapped on the surface of fresh produce and, therefore, is an important step in helping to prevent foodborne illness. But what about pesticides? The answer: sometimes yes, but not always. Researchers from the University of Connecticut published a study which looked at the ability of a rinse in tap water to remove pesticide residues from a variety of crops. Pesticides (twelve types as appropriate to the crop) were applied under normal field conditions to food-crops ranging from apples and beets to lettuce and strawberries, crops were allowed to mature, and then were harvested. Samples were either analyzed unrinsed, or after rinsing for 15-30 seconds with gentle rotation by hand under running water.

Many pesticides are applied directly to plant material where they work to protect against disease or insect invasion. Other pesticides are systemic, systemic pesticides are generally expected to move within the plant tissue. Generally, systemic pesticides are taken up by the root system and distributed throughout the plant tissue. The researchers found that levels of 9 of the 12 pesticides studied on the food crops were reduced by rinsing. Where rinsing was not effective, it appears that the pesticide moved within the plant tissue and was no longer on the surface. So rinsing of fresh produce may help to lower pesticide content for non-systemic pesticides, for those that are systemic, rinsing will be expected to have little effect. Unfortunately there is no way for consumers to know which pesticides are systemic and which are not; and even some pesticides classified as non-systemic may be transported within the plant tissue.

There are several simple steps that can add to the effectiveness of rinsing:

  • Remove the outer leaves of leafy crops such as cabbage or head-lettuce.
  • Remove the peel of crops which are reported to have higher levels of pesticides or where the texture of the surface may trap pesticides such as with peaches.
  • If applying pesticides in a home garden, be sure to apply the correct pesticide and wait for the appropriate interval before harvesting. Many pesticides break down after a period of time, so simply waiting the appropriate interval can mean that pesticides, or resides, are no longer there.
  • Choose organic as your budget allows to reduce exposure to synthetic pesticides, remembering, though, that organic growers can, and do, use approved pesticides on their crops.
  • Choose variety. Variety is the spice of life, and the best way to avoid exposure to chemical contaminants is to eat a variety of fruits and vegetables, reducing your exposure to any one food item that may have elevated pesticide levels.
  • Remember that plants produce pesticides too! Plants produce their own pesticides which help the plants to fight off invasion from pests and disease. So it’s impossible to eat fruits and vegetables, even organically grown ones, without any pesticides at all.

Stay food safe and healthy! Barb

Reference: Krol, W.J., et al. 2000. Reduction of pesticide residues on produce by rinsing. Journal of Agricultural and Food Chemistry. 48:4666-4670.