Conventionally grown fruits and vegetables commonly have pesticide residues — even after you wash and peel them.
However, residues are nearly always below the limits set by the US Environmental Protection Agency (EPA) (1).
The annual Clean Fifteen™ list — published by the Environmental Working Group (EWG) — ranks the fruits and vegetables lowest in pesticide residues, primarily based on USDA testing.
To develop the list, the EWG reviews 48 common, non-organic fruits and vegetables, including US-grown and imported items (4).
Each item’s ranking reflects a combined score from six different methods of calculating pesticide contamination (5).
Here is the 2018 Clean Fifteen list — beginning with the least pesticide-contaminated.
This healthy, fatty fruit scored the number one spot for the least pesticide-contaminated produce item (6).
Keep in mind that foods are prepared prior to the analyses, such as by washing or peeling them. As avocados’ thick skin is typically peeled, most of its pesticides are removed prior to consumption (1, 8).
Summary Avocados contain the least pesticides of any common produce item. Due in part to their thick peel, fewer than 1% of avocados tested had any pesticide residue.
However, this ranking doesn’t include residues of glyphosate, also known as Roundup, a controversial pesticide that some corn has been genetically modified to resist. The FDA has only recently started testing corn for glyphosate residues (10, 11).
If you are trying to avoid GM foods and glyphosate, buy organic corn products, which aren’t permitted to be genetically modified or sprayed with glyphosate.
Summary Sweet corn is generally low in pesticides and easily makes the EWG’s list. However, this analysis didn’t test for the pesticide glyphosate, which is used on genetically modified corn crops.
Notably, the EWG didn’t consider contamination of the environment from pesticides used to grow this tropical fruit.
Therefore, organic pineapple — whether fresh, frozen or canned — may be worth buying to encourage more sustainable farming methods.
Summary Pineapple’s thick skin helps minimize pesticide contamination of the fruit flesh. Still, the pesticides used to grow pineapple can contaminate water supplies and harm fish, so buying organic encourages eco-friendly farming.
Cabbage is also high in vitamins C and K, supplying 54% and 85% of the Reference Daily Intake (RDI) per 1 cup (89 grams) of chopped, raw leaves, respectively (19).
Summary Cabbage is a low-pesticide vegetable that contains compounds that naturally protect against insects and may reduce your risk of cancer.
Even so, there are other reasons you may want to consider buying organic onions. In a six-year study, organic onions were up to 20% higher in flavonols — compounds that may protect heart health — than conventionally grown ones (20, 21).
This may be because pesticide-free farming encourages plants to develop their own natural defense compounds — including flavonols — against insects and other pests (22).
Summary While less than 10% of tested onions showed pesticide residues, you may still want to opt for organic. Organic onions tend to be higher in heart-protective flavonols than those grown conventionally.
Snap peas, however, didn’t score as well. Snap peas grown in the US ranked as the 20th cleanest vegetable, while imported snap peas ranked as the 14th most pesticide-contaminated vegetable (4).
These poorer scores for snap peas are partly due to testing the whole pod — as snap peas are often eaten with the pod. On the other hand, sweet peas were tested after shelling. The pod can be directly exposed to pesticides and is thus likelier to be contaminated (8).
Summary The majority of frozen sweet peas don’t harbor detectable pesticide residues. However, snap peas — which are typically eaten whole — are higher in pesticide residues.
Summary About 80% of papayas are free from pesticide residues. However, most papayas are genetically modified, so if that’s a concern, choose organic.
About 90% of asparagus examined had no detectable pesticides (6).
Asparagus harbors an enzyme that may help break down malathion, a pesticide commonly used against beetles that attack the vegetable. This trait may reduce pesticide residues on asparagus (29).
This popular green vegetable is also a good source of fiber, folate and vitamins A, C and K (30).
Summary The vast majority of asparagus samples had no measurable pesticide residues. Asparagus contains an enzyme that may help break down certain pesticides.
Thiabendazole was the most common pesticide in contaminated mangoes. This agricultural chemical is considered slightly toxic at high doses, but the residue found on the fruit was very low and well below the EPA’s limit (28, 31).
One cup (165 grams) of mango boasts 76% of the RDI for vitamin C and 25% of the RDI for vitamin A (beta-carotene), which gives the flesh its bright orange color (32).
Summary Nearly 80% of mangoes were free from detectable pesticide residues, and the most common pesticide was well below the EPA’s limit.
About 75% of eggplants sampled were free of pesticide residues, and no more than three pesticides were detected on those with residues. The eggplants were first rinsed with water for 15–20 seconds, then drained (6, 8, 33).
Eggplants are susceptible to many of the same pests as tomatoes, which are both in the nightshade family. However, tomatoes are number 10 in the EWG’s Dirty Dozen™ list of most pesticide-contaminated produce, which may be partly due to their thinner skin (4).
Eggplant has a meaty texture that makes it a good main dish for vegetarians. Try cutting a medium-size eggplant into thick slices, brush lightly with olive oil, sprinkle with spices and grill to make meatless burgers.
Summary Close to 75% of eggplants analyzed were free of pesticide residues, despite the fact that these samples were tested with the peel.
The thick rind of honeydew melon protects against pesticides. About 50% of honeydew melons sampled had no detectable pesticide residues (6).
Of those with residues, no more than four pesticides and their breakdown products were identified (6).
Summary Around half of honeydew melons tested were free from pesticide residues, and those with residues had no more than four different types.
In the analysis, 65% of kiwis had no detectable pesticide residues. Among those with residues, up to six different pesticides were noted. In contrast, strawberries — which hold the number one spot in the Dirty Dozen — had residues from 10 different pesticides (4, 6).
Besides fiber, kiwi is a stellar source of vitamin C — supplying 177% of the RDI in just one medium fruit (76 grams) (35).
Summary About 2/3 of kiwis sampled had no measurable amounts of pesticide residues. Among those with detectable residues, up to six different pesticides were present.
Of 372 cantaloupes tested, over 60% had no detectable pesticide residues, and only 10% of those with residues had more than one type. The thick rind provides some protection against pesticides (6, 7).
However, harmful bacteria may contaminate the cantaloupe rind and transfer to the flesh when you cut the melon. The fruit’s netted rind and low acid levels make it conducive for bacteria (36).
To help remove bacteria — and potentially some of the pesticide residue — you should scrub cantaloupe and other melons with a clean produce brush and cool tap water before cutting. Always keep cut melons refrigerated to reduce the risk of food poisoning.
A 1-cup (177-gram) serving of cantaloupe packs more than 100% of the RDI for both vitamin A (as beta-carotene) and vitamin C (37).
Summary More than 60% of cantaloupes tested had no measurable pesticide residues. Always wash and scrub the rind of cantaloupes before cutting — not only to reduce pesticide residues but also to remove potentially harmful bacteria.
The pesticide imidacloprid was found to contaminate 30% of cauliflower samples. Though residue levels were well below the EPA limit, it’s worth noting that imidacloprid and similar pesticides are linked to declining honeybee and wild bee populations (7, 38, 39).
As a third of the global food supply depends on pollination by bees and other insects, choosing organic cauliflower can help support eco-friendly farming (40).
Summary About half of cauliflowers sampled were pesticide-free. Still, an associated pesticide can harm bees, which are vital for pollinating food crops. Therefore, organic cauliflower is the smartest choice for the environment.
Broccoli isn’t bothered by as many pests as some vegetables because it exudes the same insect-deterring plant compounds — glucosinolates — as cabbage. Most of the pesticides applied to broccoli kill fungus and weeds rather than insects (18, 43).
Like other cruciferous vegetables, broccoli is rich in plant compounds that help reduce inflammation and cancer risk. It’s also high in vitamin C and vitamin K, supplying 135% and 116% of the RDI in 1 cup (91 grams) of raw florets, respectively (42, 44).
Summary About 70% of broccoli samples were free of pesticide residues, in part because the vegetable contains its own natural insect repellents.
If your budget makes it challenging to buy organic produce but you’re concerned about pesticide exposure, the EWG’s Clean Fifteen are good conventionally grown choices with relatively low pesticide contamination.
Testing of produce sold in the US shows that the Clean Fifteen — including avocado, cabbage, onion, mango, kiwi and broccoli — often contain little or no detectable pesticide residues. Additionally, these residues are well within EPA limits.
Still, some pesticides are absorbed inside fruits and vegetables, so you can’t eliminate exposure completely.
Keep in mind that the EWG encourages people who can afford organic produce to buy it, as pesticides can have harmful environmental effects and may pose subtle health risks.