Eminent British epidemiologist, Geoffrey Rose, argued that environmental exposures and patterns of behaviour that have not been part of the historical human condition are "unnatural" and pose a possible threat to population health. In that vein, it follows that population-wide exposure to caffeine could be cause for concern. The ubiquitous presence of caffeine in the human diet is of fairly recent origin, and evidence remains mixed as to whether caffeine is protective, harmful or neither. Rose taught that when scientific consensus regarding benefits and harms is lacking, the retention of an exposure factor in a population entails greater risk of harm than its removal. Although that maxim and the precautionary principle it encapsulates imply that there should be little or no population exposure to caffeine, the exact opposite exists insofar as caffeine is consumed daily by most people worldwide. Caffeine physical dependence could lead consumers to discount cautionary advice about possible harm. On the other hand, concerns about caffeine may grow in the face of increased exposure due to an ever-expanding variety of caffeine products in the marketplace, especially products designed to appeal to children and adolescents.