If you are one of the million plus people who have received a copy of the pocket-sized guide, now in its fifth edition, you know it can act as a kind of decoder ring to help unscramble some of the competing messages about where to put your perhaps dwindling organic dollars.

“People have expressed a lot of gratitude for the guide,” wrote Jovana Ruzicic, a spokesperson for EWG, in a recent email. “They seem to feel relieved at the findings. Knowing that they can make a priority list helps overcome the stress of keeping a family or themselves healthy.”

If you’re shopping with more than your own immediate pesticide exposure in mind, however, lists like the Dirty Dozen are only one piece of the puzzle. Why? Because while the guide tells eaters how much is on the food when it’s ready to eat (this part is crucial) it doesn’t say anything about the amount used in the production of that food.

Then there’s this telling rule of thumb: by and large, the fruits and vegetables that are the most loaded with pesticides have thin skins (peaches top the list, alongside peppers, strawberries, apples, and cherries), while a number of the “cleanest” foods have a thick skin or husk, like avocado or corn — in other words, they’re the most protected.

When asked whether shoppers who use the list might have an impact on agriculture’s bigger picture, EWG’s Ruzicic was straight to the point: “We do not have any data that would support (or not support) the thesis that buying from the clean list would reduce pesticide use.”

Selyne DeYarus of the Organic Center, a research-based nonprofit with a guide of their own called Organic Essentials, acknowledges that what’s missing from the list might be equally important as what’s included.

“There are a lot of implications for the use of these chemicals that may not be direct.” she says. “You’re not as likely to be contaminated by eating an orange as you are a peach, for example, but there may be quite a lot of residue on the peel.” DeYarus also points to what she calls a “trickle down effect.”

“Those toxins still kill mammals and birds when they get in the groundwater and surface water.” And when it comes to toxicity, the health of the environment does have an eventual, if not easily traceable, impact on human health. Then there’s also the health of the people growing the food to consider.

Brian Hill, science director at Pesticide Action Network North America, says that any time a consumer chooses an organic product as an alternative to what’s on the Dirty Dozen conventional list, they are making a choice that positively impacts farm workers and their communities. But he has some reservations about the other end of the list.