The 5 Most Contaminated Foods and What to Do About Them

Not all food carries equal chemical risk. Some foods accumulate pesticide residues, PFAS or heavy metals at significantly higher levels than others, due to the crops' biology, how they are grown, and how they are packaged. Knowing which five categories to prioritise for organic sourcing or packaging swaps makes the biggest practical difference in dietary chemical exposure for the lowest additional cost.

How contamination rankings are made

The Environmental Working Group's Dirty Dozen is an annual list compiled from USDA pesticide residue testing data on conventionally grown produce. The USDA tests thousands of produce samples each year after washing, reflecting residues consumers actually encounter. EWG ranks foods by the number of different pesticides detected, the frequency of detection and the concentration. Separately, researchers at the Silent Spring Institute have ranked foods by PFAS contamination based on FDA Total Diet Study data and independent testing. These two contamination categories are distinct and affect different foods.

The five foods and why

Strawberries have topped the EWG Dirty Dozen for several consecutive years. Up to 22 different pesticide residues have been detected on a single strawberry sample. Their thin skin, high surface area and ground-level growth make them particularly susceptible to pesticide accumulation. Spinach is second: pesticide residues by weight are consistently among the highest of any vegetable. Microwave popcorn is the primary PFAS concern from packaged foods, with multiple independent studies documenting PFAS migration from bag lining to popcorn during heating. Canned food, particularly tomatoes and other acidic or fatty items, has consistently shown BPA and BPS leaching from can linings into food. Farmed Atlantic salmon carries the highest concentrations of PCBs, PBDEs and other lipophilic persistent organic pollutants of any commonly eaten fish, due to contamination in fish meal feed.

Organic versus conventional for each category

For strawberries and spinach, switching to organic eliminates or dramatically reduces pesticide residue exposure. USDA data consistently shows certified organic strawberries have negligible detectable residues compared to conventional. For microwave popcorn, organic certification does not address the PFAS packaging; the fix is switching to stovetop or air-popped popcorn entirely. For canned food, switching to glass jars or Tetra Pak eliminates bisphenol exposure from can linings. For salmon, switching from farmed Atlantic to wild-caught Pacific salmon (sockeye, coho, Chinook) or to sardines dramatically reduces persistent organic pollutant exposure.

The Clean Fifteen

The EWG also publishes an annual Clean Fifteen: the 15 foods least likely to carry pesticide residues when conventionally grown. These include avocados, sweet corn, pineapples, onions, papayas, frozen sweet peas, asparagus, honeydew, kiwi, cabbage, mushrooms, mangoes, sweet potatoes, watermelon and carrots. Buying organic for Clean Fifteen items is low priority from a pesticide perspective, though other environmental considerations may still apply.

A practical approach