Introduction rnAssessment of environmental health effects arising from exposure to multiple substances is often very challenging.This is particularly true when humans are exposed to a mixture that contains both beneficial and harmful substances.A good example relates to the risk and benefits of fish consumption.Fish contain a variety of essential nutrients,such as omega-3 fatty acids and proteins,which are beneficial to human health.Fish may also contain trace amounts of environmental contaminants,such as polychlorinated biphenyls (PCBs),which can disrupt endocrine function.How would environmental health studies confront the challenges of assessing the adverse and beneficial effects from food consumption? A recent study (Haslam et al.,2015) published in the Joal of Environmental Sciences demonstrates an example of an approach based on environmental epidemiology to tackle this complex problem.