Blueberries are a healthy treat. Full of antioxidants and anti-inflammatory properties, the blue fruit is practically a superfood. According to a group of researchers, however, the tart berry has one major flaw — pesticides.

Since 2004, the nonprofit health organization Environmental Working Group (EWG) has been ranking the pesticide contamination of the 46 most popular fruits and vegetables in its “Shopper’s Guide to Pesticides in Produce.” Utilizing data provided by the Department of Agriculture and the Food and the Drug Administration, EWG bases its rankings on information from over 46,000 various samples of produce.

“It is important to note that the samples are tested for pesticides by the USDA and the FDA after they have been prepared to be eaten,” the EWG reported. “This means the produce has been thoroughly washed and, when applicable, peeled. After these preparations, pesticide residues are still detected on many of the fruits and veggies.”

According to the 2023 “Shopper’s Guide to Pesticides in Produce” report, 12 different fruits and vegetables made it onto EWG’s list of most pesticide contaminated foods. Known as the “Dirty Dozen,” these foods tested positive for a whopping 210 pesticides. Blueberries are the latest fruit to make it onto the list.

“Some of the USDA’s tests show traces of pesticides long since banned by the Environmental Protection Agency,” the report said, according to CNN. “Much stricter federal regulation and oversight of these chemicals is needed.”

Strawberries topped the “Dirty Dozen” list, followed by spinach, kale, peaches, pears, nectarines, apples, grapes, bell peppers, cherries, blueberries and green beans.

“Pesticides are toxic by design,” Jane Houlihan, former senior vice president of research for EWG, told CNN. “They are intended to harm living organisms, and this inherent toxicity has implications for children’s health, including potential risk for hormone dysfunction, cancer, and harm to the developing brain and nervous system.”