With many essential oils, you probably don’t have much to worry about in terms of pesticide contamination—even if the plants were sprayed.
Turns out most essential oils are produced through a process called steam distillation, which does a pretty great job of separating the essential oil from plant material and everything else, including pesticide residue. During the process, plants such as lavender or peppermint are placed inside a metal still where steam breaks them down, causing their tiny volatile compounds to rise up into another part of the still via water vapor. There, the steam condenses into liquid and the essential oils eventually separate from the water molecules. Then the oils are siphoned off and eventually bottled and sold.
“These oils have such a tiny molecular structure—that’s why distillation works so well and takes only essential oils out of the plant material, leaving nearly everything else behind,” says Kathi Keville, director of the American Herb Association and author of Aromatherapy: A Complete Guide to the Healing Art.
But this isn’t the case with most citrus essential oils (e.g. tangerine, lemon, bergamot, sweet orange, grapefruit, and lime). Not only is citrus commonly sprayed with pesticides, these fruits are transformed into essential oils via a cold-pressing process. With cold-pressing, the rind is essentially just squeezed to remove the volatile oils.
“Contamination is definitely a concern because there is no process of adequately removing the pesticides from the rind, and there’s no separation of the oil,” says Mariza Snyder, D.C., functional wellness practitioner and author of The Essential Oils Hormone Solution. In fact, a 2015 research analysis looking at the pesticide residues of nearly 30 different essential oils found that cold-pressed citrus oils were much more likely to contain pesticide residue (in some cases exceeding levels deemed safe) than steam-distilled oils.
So should you always buy organic citrus oils? “Oils are lipophilic, which means they’re going to get into the tissues really fast,” says Snyder. “We’re living in a time when we really don’t need more toxicity, so citrus oils definitely need to be tested for purity, or at least made with organic plants to be using them on a day-to-day basis.”