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Organic Foods Avoid Pesticides and the Dirty Dozen

Dear Dr. Dave and Dr Dee,

I rinse apples with water before eating, but my roommate actually uses soap and water to wash her apples. Isn't that strange? Also, she says that I should only buy organic and natural food products because they are healthier, is that true?


Food for Thought

Dear Food for thought,

Washing apples with soap and water is actually a better way to wash off pesticide residues and bacteria than simple water rinsing. For example, 50-93% of the pesticide residues remained on apples when rinsed solely with water. Simple water rinsing only removed 25% of bacteria on apples and pears, but washing with soap and water or spraying with a vinegar solution then rinsing removed at least 98%. But, pesticides are not just found on the surface of the apple (or other fruit and vegetables), the contaminate can be in the flesh of the plant too if it has absorbed pesticides through their roots or leaves. (Heaton, S., "Organic farming, food quality and human health: A review of the evidence," The Soil Association, Bristol, 2001; (“Cleaning Smooth-Skinned Produce, Cook's Illustrated,, September 1, 2007).

Organic is healthier, but the term "natural" labeled on food does not mean the same as organic (described below, WHAT IS THE DIFFERENCE BETWEEN ORGANIC AND NATURAL?).

For the best cleaning method for produce, see below (WASHING PRODUCE: BEST METHOD).


Organic food is healthier both in terms of safety and nutrition.

SAFETY: A review of studies found organic foods had less pesticide residues and antibiotic-resistant bacteria. Lower urinary pesticide levels were found in children on organic diets compared to regular diets. (Smith-Spangler, C., Brandeau, M.L, Hunter, G.E., Bavinger, J.C., Maren Pearson, BS; Eschbach, P.J., Sundaram, V., Liu, H., Schirmer, P., Stave, C., Olkin, I., Bravata, D.M., "Are Organic Foods Safer or Healthier Than Conventional Alternatives?: A Systematic Review," Annals of Internal Medicine, 4 September 2012;157(5):348-366).

NUTRITION: Organic foods have higher levels of nutrients, essential minerals, and vitamins (especially vitamin C) compared to non-organic food. Organic milk had higher levels of heart healthy omega-3 fatty acids and Vitamin E versus non-organic milk, plus organic milk comes from cows neither fed GMO (genetically modified organism) nor given growth hormones nor antibiotics. ("Nutritional Considerations," Organic Trade Association,, 2011; "The nutritional benefits of organic milk – a review of the evidence," Soil Association 2005).

A two year experiment evaluating organic and non-organic strawberries grown in similar soil using the same varieties of strawberries found organic strawberries had significantly higher levels of vitamin C and antioxidants (anti-aging), the soil was healthier, and the fruit had a longer shelf life. (Reganold, J.P., Andrews, P.K., Reeve, J.R., Carpenter-Boggs, L., Schadt, C.W., Alldredge, J.R., Ross, C.F., Davies, N.M., Zhou,J., "Fruit and Soil Quality of Organic and Conventional Strawberry Agroecosystems,", September 1, 2010).

Reganold, et. al. also examined studies comparing nutrition of organic and conventional foods over the past 10 years. The findings indicate that 8 of 10 review studies concluded the organic products to be more nutritious. (Reganold, et. al., "Fruit and Soil Quality of Organic and Conventional Strawberry Agroecosystems,", September 1, 2010).


In the U.S. over 1,055 active ingredients are registered as pesticides for use in the U.S. ("Pesticides: Topical & Chemical Fact Sheets," U.S. EPA, April 5, 2007).

In agriculture, nearly a billion (877 million) pounds of pesticides are used each year in the U.S., which can contaminate the soil, water, and air, and accumulate in the food chain. For example, although DDT had been banned for decades, traces were still found in some carrots. (Grube, A., Donaldson, D., Kiely T., Wu, L., "Pesticides Industry Sales and Usage 2006 and 2007 Market Estimates," U.S. EPA, 2011; Aktar, W., Sengupta, D., Chowdhury, A., "Impact of pesticides use in agriculture: their benefits and hazards," Interdisciplinary Toxicology, 2(1), March 2, 2009).

High exposure to pesticides has been linked to cancers of the stomach, breast, prostate, brain, and skin. (Heaton, S., "Organic farming, food quality and human health: A review of the evidence," Soil Association, soil, 2001).


According to the USDA (U.S. Department of Agriculture), "the overall pesticide residues found on foods tested are at levels well below the tolerances set by the EPA," but recommends washing fruits and vegetables before eating. ("USDA Releases 2010 Annual Summary for Pesticide Data Program, May 25, 2012). Unfortunately, crops are sprayed with many different types of pesticides. The combinations of pesticides on (and in) foods could have toxicological interactions, but this has not been examined. (Heaton, S., "Organic farming, food quality and human health: A review of the evidence," The Soil Association, Bristol, 2001).

A Harvard study found that a child's brain chemistry could be affected by small allowable amounts of a common pesticide. OP (Organophosphate) insecticides are widely used pesticides in the U.S. Children with above-average pesticide exposures were twice as likely to have ADHD. (Bouchard, M.F., Bellinger, D.C., Wright, R.O., Weisskopf, M.G., "Attention-Deficit/Hyperactivity Disorder and Urinary Metabolites of Organophosphate Pesticides," Pediatrics, February 23, 2010).

Three different long-term prenatal studies found OP pesticides associated with lower cognitive development in childhood. University of California Berkeley researchers found that 7-year old children of women who had been exposed to higher amounts of an organophosphate pesticide during pregnancy had "poorer intellectual development" (Bouchard, M.F., Chevrier, J., Harley, K.G., Kogut, K., Vedar, M., Calderon, N., Trujillo, C., Johnson, C., Bradman, A., Barr, D.B., Eskenazi, B., "Prenatal Exposure to Organophosphate Pesticides and IQ in 7-Year-Old Children," Environmental Health Perspectives, 2011 August, 119(8): 1189-1195).

Another longitudinal study of prenatal exposure to OP pesticides (specifically CPF - chlorpyrifos) and neurodevelopment of their children at age 7 found that for each standard deviation increase in CPF exposure, IQ declined by 1.4% and memory declined by 2.8% (Rauh, V., Arunajadai, S., Horton, M., Perera, F., Hoepner, L., Barr, D.B., Whyatt, R., "Seven-Year Neurodevelopmental Scores and Prenatal Exposure to Chlorpyrifos, a Common Agricultural Pesticide," Environmental Health Perspectives, 2011 August, 119(8): 1196-1201).

Engel, et. al. found prenatal exposure to OP "negatively associated with cognitive development, particularly perceptual reasoning, with evidence of effects beginning at 12 months and continuing through early childhood" (Engel, S.M., Wetmur, J., Chen, J., Zhu, C., Barr, D.B., Canfield, R.L., Wolff, M.S., “Prenatal Exposure to Organophosphates, Paraoxonase 1, and Cognitive Development in Childhood,” Environmental Health Perspectives, 2011 August, 119(8): 1182-1188).


Eating a healthy diet with half your plate each meal consisting of fruits and vegetables may reduce the risk of cancer and other chronic diseases (stroke, type 2 diabetes, heart disease). ("Nutrition for Everyone: Fruits and Vegetables," Centers for Disease Control and Prevention,, October 29, 2012).

Organic farming prohibits nearly all pesticides, so residues are rarely found. Some non-organic produce are more susceptible to pesticide residue than others, and therefore would be best to buy organic. (Heaton, S., "Organic farming, food quality and human health: A review of the evidence," The Soil Association, Bristol, 2001).

In brief below are the Environmental Working Group list of the "dirty dozen" and amount of pesticide residues found on each (Shapley, D., "The New Dirty Dozen: 12 Foods to Eat Organic,", 2012):


1. Apples: more than 40 different pesticides

2. Celery: more than 60

3. Strawberries: nearly 60

4. Peaches: more than 60

5. Spinach: nearly 50

6. Nectarines (Imported): 33 pesticides

7. Grapes: more than 30

8. Sweet Bell Peppers: nearly 50

9. Potatoes: more than 35

10. Blueberries: more than 50

11. Lettuce: more than 50

12. Kale and Collard Greens (tie): more than 45

OTHER NON-ORGANIC FOODS WITH PESTICIDE RESIDUES: In addition to the Dirty Dozen, Shapley also warns about these foods below (Shapley, D., "The New Dirty Dozen: 12 Foods to Eat Organic,", 2012; "What‘s on my food,", 2012):

1. FATTY MEATS: Beef muscle generally has no pesticides, however fat is another story. Ten pesticides have been detected in beef fat, including chemicals that accumulate in human fats just as they do in beef cattle. Pork fat and chicken thighs tally the most pesticide residue with 8 pesticide residues found in each, while lean meat has zero.

2. MILK (12 Different Pesticides): Pesticides and other man-made chemicals have been found in human breast milk, so it should come as no surprise that they have been found in dairy products, too. Milk is of special concern because it is a staple of a child's diets.

3. COFFEE: Many coffee beans that we buy are grown in countries with lax regulations for use of pesticides. Look for the USDA Organic label to ensure you're not buying beans that have been grown or processed with the use of potentially harmful chemicals.

4. WINE: Grapes are part of the Dirty Dozen and heavily doused with pesticides to ward off fungus and bugs. Look for wine labeled "made with organic grapes," rather than "organic wine" because winemakers add sulfites as a preservative to allow for long-distance shipping.

5. CHOCOLATE: Similar to coffee beans, cocoa beans are grown in developing countries without strict laws governing use of pesticides.


All produce, whether non-organic or organic should be washed in order to remove dirt, bacteria, and pesticide residues. The U.S. Food and Drug Administration (FDA) does not recommend washing produce with soap and water because soap residue could be ingested if not rinsed thoroughly or soap could be absorbed into the porous skin. Yet, if absorption into the skin is a concern, then wouldn't pesticide sprays also be absorbed into the skin?

The FDA recommends simply washing produce under running water before eating, cutting, or cooking. In addition, hands should be cleaned with soap and water before and after preparation. Outer leaves of lettuce or cabbage should be discarded before washing. A clean produce brush can be used on firm skin produce while rinsing (i.e. carrots, squash, melons, cucumbers, potatoes, apples). Even if you do not plan to each the outer skin or rind, washing removes bacteria and pesticides that could transfer to the inner flesh. Produce with lots of crevices such as broccoli should be soaked in water for a couple of minutes and then rinsed. Dry produce with a clean paper towel. ("Food: Raw Produce: Selecting and Serving It Safely," U.S. Food and Drug Administration,, 4/5/2012; Schroeder, M., Kendall, P., "A Closer Look at Produce Washes," Colorado State University Extension SafeFood Rapid Response Network,, Winter/Spring 2005).

However, Cook's Illustrated Magazine tested four methods of washing apples and pears and found that simple water rinsing only removed 25% of germs. They recommend spraying with a vinegar solution (1 part vinegar to 3 parts water) and then rinsing with water, which killed 98% of bacteria, almost as effective as soap and water. Scrubbing with a brush removed about 85%. ("Cleaning Smooth-Skinned Produce," Cook's Illustrated,, September 1, 2007).


The terms organic and natural are not synonymous. Organic products must adhere to strict farming and processing regulations, with no GMO (genetically modified organisms) and most pesticides prohibited. The term "natural" refers to products that are minimally processed, but can still contain GMO and pesticide residues. For example, meat labeled natural cannot contain artificial additives (colors, flavors, preservatives, or sweeteners), but the animal could have been fed GM feed, given growth hormones, or antibiotics. However, if labeled organic meat, then the meat is both natural (no artificial additives) plus the animal has not been raised on GM feed nor given hormones nor antibiotics. (Benson, J., "Know the difference: 'Natural' foods are not organic, often contain GMOs and other toxins,", March 14, 2012).


Organic certification began in 2002. The U.S. Department of Agriculture (USDA) defines organic crops, livestock, and multi-ingredient foods as follows ("National Organic Program Organic Standards," United States Department of Agriculture Agricultural Marketing Service, 9-10-12):

1) Organic Crops. The USDA organic seal verifies that irradiation, sewage sludge, synthetic fertilizers, prohibited pesticides [herbicides, insecticides, fungicides], and genetically modified organisms were not used. [Roundup would be prohibited].

2) Organic Livestock. The USDA organic seal verifies that producers met animal health and welfare standards, did not use antibiotics or growth hormones, used 100% organic feed, and provided animals with access to the outdoors.

3) Organic Multi-ingredient Foods. The USDA organic seal verifies that the product has 95% or more certified organic content. If the label claims that it was made with specified organic ingredients, you can be sure that those specific ingredients are certified organic.

According to the U.S. Department of Agriculture (USDA), foods labeled organic are required to be grown, harvested, and processed according to national standards that include restrictions on use of pesticides, hormones, antibiotics and genetically modified organisms ("Understanding Organic Labeling," United States Department of Agriculture Agricultural Marketing Service, 7-27-09).

When buying organic, look for the following regulated terms on food labels:

a) "100% Organic": contains 100% certified organic ingredients.

b) "Organic": 95% or more organic ingredients.

c) "Made with Organic Ingredients": at least 70% organic ingredients.

CLEAN 15: The Environmental Working Group lists these 15 non-organic produce as having the least pesticide residues, of which most have an outer covering that is peeled before eaten. (Daily Green Staff, "The Clean 15: Foods You Don’t Have to Buy Organic,", 2012; "What‘s on my food,", 2012):


1. Onions: 1 pesticide residue

2. Sweet Corn: 1 found on fresh; 0 on frozen

3. Pineapple: 6 pesticide residues found

4. Avocado: # not listed

5. Asparagus: 9 pesticide residues

6. Sweet peas: 12 found

7. Mango: # not listed

8. Eggplant: 18 found

9. Cantaloupe (domestic): 27 found

10. Kiwi: #not listed

11. Cabbage: # not listed

12. Watermelon: 28 found

13. Sweet Potatoes: 8 found

14. Grapefruit: 11 found

15. Mushrooms: 14 found

For more information: