If you're concerned about food safety, you probably already look for organic produce at the supermarket. But if you can't always buy organic, you can still dramatically lower your family's exposure to chemical pesticides by choosing the least pesticide-contaminated fruits and vegetables with the Shopper's Guide to Pesticides in Produce.

The Shopper's Guide is a handy, wallet-size card that lists the "Dirty Dozen" most contaminated fruits and vegetables, as well as the 12 most "Consistently Clean" items. It's available for free download at www.foodnews.org. The newest edition of the Guide comes in both English and Spanish versions for the first time.

The Shopper's Guide was developed by Environmental Working Group (EWG), based on the results of nearly 43,000 tests for pesticides on produce by the Department of Agriculture and the Food and Drug Administration between 2000 and 2004. EWG's computer analysis found that consumers could cut their pesticide exposure by almost 90 percent by avoiding the most contaminated fruits and vegetables and eating the least contaminated instead.

Eating the 12 most contaminated fruits and vegetables will expose a person to about 15 pesticides a day, on average. Eating the 12 least contaminated will expose a person to fewer than two pesticides a day.

"Federal produce tests tell us that some fruits and vegetables are so likely to be contaminated with pesticides that you should always buy them organic," said Richard Wiles, EWG's senior vice president. "Others are so consistently clean that you can eat them with less concern. With the Shopper's Guide in your pocket, it's easy to tell which is which."

EWG's analysis of federal testing data found:

• Peaches and apples topped the Dirty Dozen list. Almost 97 percent of peaches tested positive for pesticides, and almost 87 percent had two or more pesticide residues. About 92 percent of apples tested positive, and 79 percent had two or more pesticides. The rest of the Dirty Dozen include sweet bell peppers, celery, nectarines, strawberries, cherries, pears, imported grapes, spinach, lettuce, and potatoes.
• Onions, avocados, and sweet corn headed the Consistently Clean list. For all three foods, more than 90 percent of the samples tested had no detectable pesticide residues. Others on the Consistently Clean list include pineapples, mango, asparagus, sweet peas, kiwi, bananas, cabbage, broccoli, and papaya.

There is growing scientific consensus that small doses of pesticides can adversely affect people, especially during vulnerable periods of fetal development and childhood when exposures can have long lasting effects. Because the toxic effects of pesticides are worrisome, not well understood, or in some cases completely unstudied, shoppers are wise to minimize exposure to pesticides whenever possible.

While washing and rinsing fresh produce can reduce levels of some pesticides, it does not eliminate them. Peeling also reduces exposures, but valuable nutrients often go down the drain with the peel. The best option is to eat a varied diet, wash all produce, and choose organic when possible to reduce exposure to potentially harmful chemicals.

Although the Shopper's Guide only measures pesticide residues on produce, buying organic also makes sense if you're concerned about bacterial contamination. Organic farmers meet all the sanitation standards required of conventional growers and, on, top of that, meet tight restrictions on the use of compost and other organic material that do not apply to conventional fruit and vegetable growers.