The Environmental Working Group, a watchdog organization in Washington, D.C., has just released their annual report to help consumers make more informed choices in the produce aisle. Their lists -- known as the "Dirty Dozen" and "Clean 15" -- analyze data on pesticide levels of 48 commonly sold fruits and vegetables.

The list is guaranteed to disappoint anyone who loves an apple a day, but will be good news if you can't live without guacamole.

The USDA has set limits on allowable pesticide residue it deems safe and requires all produce sold in stores to meet those standards. But this doesn't prevent lower levels of chemicals from making an appearance in your fruits and vegetables.

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"The USDA washes and peels the produce items that it tests and they still find pesticide residues on 65 percent of the samples," Alex Formuzis, vice president of EWG, told CBS News.

The organization says allowable levels of pesticide haven't changed significantly in over a decade.

EWG reports all nectarine and 99 percent of apple samples tested positive for at least one pesticide residue. Just one single grape contained as many as 15 pesticides, while single samples of celery, cherry tomatoes, imported snap peas and strawberries were found to have 13 different pesticides each.

This year's list also examined pesticide levels on leafy greens, such as kale and collard greens, as well as hot peppers. Some of these produce items were found to have residues of organophosphate and carbamate insecticides, which research has shown are especially toxic.

In a number of medical studies, pesticide exposure has been linked to Alzheimer's and Parkinson's disease, autism and endometriosis.

However, EWG and other health experts emphasize that these findings don't mean you should skip the strawberries. The benefit of any diet rich in fruits and vegetables far outweighs the risks of low levels of pesticide exposure.

The group suggests sticking to organic produce for items at the top of the list. Or if organic produce costs too much, consider loading up your shopping cart instead with the fruits and veggies at the bottom of the list, which includes sweet corn, pineapples, mangoes and eggplant. The majority of "clean" produce has thick skin which means chemicals are less likely to be absorbed entirely.

Thankfully, the report also included also some positive findings: Only 1 percent of avocados had detectable pesticides. On the group's list of "Clean Fifteen" fruits and veggies, only 5.5 percent contained two or more pesticides, and no sample tested positive for more than four.

Here is the Environmental Working Group's list of the "Dirty Dozen" fruits and vegetables:

Apples Strawberries Grapes Celery Peaches Spinach Sweet bell peppers Nectarines Cucumbers Cherry tomatoes Snap peas Potatoes

See the entire list on the EWG Web site -- including fruits and veggies with lowest pesticide levels.