The SFD Graphic shows the percentage of the population whose excreta are considered to be either safely managed or unsafely managed. Safely managed and unsafely managed in this context indicates the likelihood of a population being exposed to a hazard as a result of the flow of excreta through the sanitation service chain, rather than absolute risk. Estimating the absolute risk would require accurate information on the level of hazard (concentrations and volumes of known pathogens at any point in the service chain), etiology and dose-response curves for those known pathogens, and information on the timing, duration and age profile of population exposed to the hazard; assessing these would require significant additional data collection and analysis.