Apples have come up the number one in the list of most contaminated fruits and vegetables in the seventh study by the US based Environment Working Group ( EWG - a public health advocacy group). Their research shows that potentially 92 percent of apples in the market could be contaminated with as many as two pesticides.

The research was on 53 fruit and vegetables and identified which had the most and least pesticides when the produce was washed and peeled. Apples moved up three places from last year, replacing celery as the number one. Strawberries are now number three.

"We think what's happening to apples is more pesticides and fungicides are being applied after the harvest so the fruit can have a longer shelf life," says EWG analyst Sonya Lunder. "Pesticides might be in small amounts, but we don't know what the subtle, long-term effects of many of these pesticides are yet."

 A "Dirty" List has been developed based on the research;

1. Apples
2. Celery
3. Strawberries
4. Peaches
5. Spinach
6. Nectarines (imported)
7. Grapes (imported)
8. Sweet bell peppers
9. Potatoes
10. Blueberries
11. Lettuce
12. Kale/collard greens

The authors of the research recommend that people eat only organic members of this list to reduce the likelihood of pesticide consumption. It is important to remember that is is still essential to wash organic produce before use.

The produce that had the least amount of pesticides have been included in the "Clean" List for 2011;

1. Onions
2. Corn
3. Pineapples
4. Avocado
5. Asparagus
6. Sweet peas
7. Mangoes
8. Eggplant
9. Cantaloupe (domestic)
10. Kiwi
11. Cabbage
12. Watermelon
13. Sweet potatoes
14. Grapefruit
15. Mushrooms

 The authors determined the ranking of the produce by rating the following for each fruit or vegetable and determining the overall score;

 •percentage of samples with two or more pesticides.

 •Average number of pesticides found on a single sample.

•Average amount (level in parts per million) of all pesticides found.

 •Maximum number of pesticides found on a single sample.

 •Total number of pesticides found on the commodity.

 With an increasing consumption of fruit and vegetables, it is worth thinking about this study when making purchases.