A key issue in the sociological study of health and illness is UNCERTAINTY.  From fears of vaccines, trying to understand cancer clusters, or any other number of protest health social movements, they all hinge on the fundamental dimension of uncertainty and how lay people understand and act on it.  This is especially the case for social movements countering accumulated scientific evidence.  Ranging from calculated risks and probabilities to personal experience, or from the scientific method and its evidence to experiential knowledge, uncertainty allows the individual cause for trust or cause for alarm.