Conventionally farmed Brussels sprouts are sprayed with several pesticides, including chlorpyrifos, dimethoate, and imidacloprid. Chlorpyrifos is the third most commonly used pesticide on Brussels sprouts in California. However, it is worth noting that the Environmental Working Group ranks Brussels sprouts among those vegetables with the least amount of pesticide residue. In addition, bugs do not like Brussels sprouts, so they are not sprayed as heavily as some other crops. If you are concerned about pesticide residues, it is recommended that you buy organic produce, including organic Brussels sprouts