This results in numerical loading limits drastically more restrictive than Part 503 and would effectively eliminate long-term biosolids application. This philosophy also translates into an attempt to find and protect the most sensitive individual or population subset within a community or ecosystem. A basic tenet of Part 503 is the explicit recognition that biosolids are a valuable resource. Clearly, we have decided that 1-2 deaths per 10,000 patients treated is a cost we are willing to bear in order to reap the benefits of penicillin use. Similarly, we have concluded that the negative effects of managing biosolids in compliance with Part 503 are not sufficient cause to forego the substantial societal benefits of land-based biosolids recycling.
Some issues remain unresolved.
It sounds very self-serving for academics to trumpet the need for more research, but I hope it stems from a noble motive. Specifically, we must never fall into the trap of thinking we are too knowledgeable to learn more, to modify our personal positions, or to acknowledge that we have overlooked a particular issue. If there is good cause to believe we have overlooked an important exposure pathway or risk scenario, we want to know about it so we can learn how to manage the risk for the protection of health and the environment. In the area of nutrients, quantitative guidelines based on biosolids and soil characteristics are not available for including phosphorus in nutrient management plans. Unresolved microbiological issues include potential regrowth of pathogens in stored biosolids, improved methods for detecting and enumerating Salmonella , and the relative public health risks of emerging pathogens such as E.coli 0157, Cryptosporidium , and viruses not detected by the current plaque assay method.