Sewage sludge--looking upstream: the precautionary principle.

The health care industry makes a unique contribution to the potential public health and environmental impacts of sewage sludge production and disposal. As materials flow into and out of health care facilities, potentially hazardous substances, like mercury, solvents, and pharmaceutical compounds, are introduced into the waste stream and ultimately into sewage sludge. Although the hazards posed by these practices are often not fully understood or the risks quantified, concern about impacts on public health and the environment is fully justified. How to deal with the uncertainties surrounding the impacts of these practices becomes an ethical as well as a scientific question. A precautionary approach to materials manufacture, use, and disposal encourages us to look upstream and to re-design products and systems in ways that primarily prevent problems rather than dealing with them at the "end of the pipe." Early warning systems, shifting the burden of proof, alternatives assessment, and monitoring programs are suggested as interventions that might be used as part of a precautionary approach to addressing the generation and disposal of sewage in an industrial society.