Science, advocacy, human and environmental health.

Medicine and public health sciences are applied sciences. The research upon which these are based is mission-oriented and as such they are underlain by advocacy. Ecological sciences, by way of parallel, involve managing ecological systems so they can remain healthy to support productive natural processes and the human population. In any eco-system, however, renewal has associated with it naturally occurring background levels of diseases and death. These are normal in all biological systems. 'Sustainable development' has been focused on commodity-based, managed systems where the goal is to ensure that the needs of growing human populations are met, producing healthy people. This objective is deemed by the Ecological Society of America to be too narrow. Priority should rather be given to the sustainability of natural ecosystems, otherwise the biosphere that sustains all life forms is neglected. Epidemiologists concerned with the health of populations need to recognize that human health and the health of natural systems have entwined destinies. Some convictions about limits, about the role of disease, degeneration, and death in healthy, that is, stable and sustainable human ecologies, ought to be embedded into any ethics for epidemiologists.