Evaluating the potential health impacts of chemical, physical, and biological environmental factors represents a challenging task with profound medical, public health, and historical implications. The history of public health is replete with instances, ranging from tobacco to lead and asbestos, where the ability to obtain evidence on potential environmental hazards has been impaired and the publication of results delayed because of commercial interests. The burden of proof is heavy on those trying to change the status quo when that involves highly profitable industries. When evaluating potential hazards that are linked with industrial activities, it is often the case that only after proof of human or environmental harm becomes undeniable are steps finally taken to control or reduce future hazards. This approach has the net effect of delaying and postponing action, allowing dangerous practices to continue until health or environmental risks have become undebatable.