In the United States the EPA mandates certain treatment processes designed to significantly decrease levels of certain so-called indicator organisms, in biosolids. These include, "...operational standards for fecal coliforms, Salmonella sp. bacteria, enteric viruses, and viable helminth ova."
However, the US-based Water Environment Research Foundation has shown that some pathogens do survive sewage sludge treatment.
EPA regulations allow only biosolids with no detectable pathogens to be widely applied; those with remaining pathogens are restricted in use.