Just because your favourite superfood is super healthy doesn’t mean it comes without headaches. In fact, some of the biggest health boosters in your fridge may be laced with unwanted residues.

Blueberries: These antioxidant-dense berries are full of vitamins C and E as well as magnesium, selenium and fibre. Oh, and some of the highest pesticide residues—even after you wash them thoroughly. Up to 13 pesticides have been found on a single berry.

Cherries: The antioxidant anthocyanin in cherries is great for joints, and cherry juice is actually a surprising painkiller. These red wonders are also on the dirty-dozen list of produce high in pesticides, with 90% of cherry samples revealing chemical residues.

Green Tea: Green tea leaves are chock full of flavonoids and other cancer-fighting polyphenols that are definitely sip-worthy. The only problem is that pesticide residues have frequently been found on imported tea. Moreover, a 2005 study found that 32% of Chinese tea samples exceeded national standards for lead thanks to leaded gas air pollution. Until 2013, when leaded gas is phased out globally, look for green tea from Japan or Morocco (where gas is already unleaded) as well as certified-organic sources to be sure it’s free of pesticide residues. (The Canadian Food Inspection Agency says all Japanese imports, including green tea, are screened to ensure they don’t exceed radiation safety limits.)

Salmon: Gotta love salmon’s omega-3 fatty acid–rich flesh. It just bites that the farmed stuff has 16 times more PCBs, dioxins and chemical pesticides than the wild kind. Spend the extra money and buy wild Pacific salmon. And remember, mackerel and herring actually have more omega-3s (sardines are tied with salmon) and fewer contaminants. Canned salmon is always wild, by the way.

Kale: Richer in antioxidants than almost any other vegetable. On top of vitamins C, K, A and beta carotene, it’s got calcium, magnesium and much more. You can just taste the health. Too bad it’s also the tenth most tainted piece of produce (75% of 20,000 samples had detectable pesticide residues).

Chocolate: Yes, dark chocolate is definitely the sexiest superfood, with many touted health benefits, but you want to make sure you avoid the usual pesticide-sprayed, labour-rights fiasco that is conventional west African–grown chocolate and get your fix from certified-organic/fair-trade sources instead. European studies found pesticide residues on 10% of chocolate.

Strawberries: Yet another über-beneficial berry loaded with anti oxidants that’s great for your heart, eyes, skin—pretty much every part of your body. It’s also got the highest pesticide residues of any fruit besides peaches, and commonly carries about three types of pesticide on its skin. Get it organic instead!

Excerpted from Ecoholic Body by Adria Vasil Copyright © 2012 by Adria Vasil. Excerpted by permission of Vintage Canada, a division of Random House of Canada Limited. All rights reserved.