Wondering if you should spend the extra money for organic? Food products babies and kids eat that are worth purchasing organic are listed below, along with why and how much more you’ll likely pay.

What: Apples, bell peppers, celery, cherries, imported grapes, nectarines, peaches, pears, potatoes, red raspberries, spinach, and strawberries.

Why: The U.S. Department of Agriculture’s own lab testing reveals that even after washing, some fruits and vegetables consistently carry much higher levels of pesticide residue than others. Based on an analysis of more than 100,000 U.S. government pesticide test results, researchers at the Environmental Working Group (EWG), a research and advocacy organization based in Washington, D.C., have developed the “dirty dozen” fruits and vegetables, above, that they say you should always buy organic if possible because their conventionally grown counterparts tend to be laden with pesticides. Among fruits, nectarines had the highest percentage testing positive for pesticide residue. Peaches and red raspberries had the most pesticides (nine) on a single sample. Among vegetables, celery and spinach most often carried pesticides, with spinach having the highest number (10) on a single sample. (For more information on pesticide levels for other types of produce, go to www.foodnews.org.)

What you’ll pay: About 50 percent more on average for organic produce, but prices vary based on the item and the time of year. A Consumer Reports price survey conducted in the New York City area in October 2005 found a premium of 24 percent on organic strawberries and 33 percent on grapes and spinach. Organic Idaho potatoes cost 101 percent more than conventional. When you buy organic produce in season at a farmer’s market or directly from local providers, however, you might avoid paying a premium at all.

What: Meat, poultry, eggs, and dairy.

Why: You greatly reduce the risk of exposure to the agent believed to cause mad cow disease and minimize exposure to other potential toxins in nonorganic feed. You also avoid the results of production methods that use daily supplemental hormones and antibiotics, which have been linked to increased antibacterial resistance in humans.

What you’ll pay: Often double the price of nonorganic, though you might save money by buying direct from local farms. For instance, in December 2005 the Organic Trade Association reported that in Iowa, organic ground beef was available for $4.25 a pound and beef tenderloin for $16 a pound.

What: Baby food.

Why: Children’s developing bodies are especially vulnerable to toxins and they may be at risk of higher exposure. Baby food is often made up of condensed fruits or vegetables, potentially concentrating pesticide residues. Michelle Faist, a spokeswoman for Del Monte, says that even though its baby foods are not organic, pesticides and heavy metals are kept below government-recommended levels.

What you’ll pay: Varies widely by store. See our thrifty tips for buying organic baby food.