Bioaccumulation is the process of contaminants building up in organisms over time. It includes bioconcentration, where contaminants are absorbed directly from the environment, and biomagnification, where contaminants increase through the food chain. Exposure to contaminants depends on their availability in the environment. Pesticides used in agriculture are a major concern, with over 4 million tonnes applied globally each year. This amount is expected to rise due to population growth and increased food demand.