This delay may provide a means to differentiate a release of fresh human feces from pollution from leaking sewage mains or septic tanks. Bacteriophage of Bacteroides sp. may also be useful. No nonculturable pathogens were found that are reliable indicators of fecal pollution. The use of gene probes coupled with polymerase chain reaction amplification of bacterial DNA can distinguish specific strains of bacteria and may have the potential to distinguish bacteria from human and non-human sources. The method is relatively rapid and comparable with standard plate counting.
More work is required to overcome interference and to establish a database of genetic fingerprints.
The fecal sterol coprostanol is found in the feces of humans through the bacterial metabolism of cholesterol in the intestinal tract. It is also excreted by a variety of other mammals, and has been found in Antarctic sediments, where it originates from marine mammals. Coprostanol is degraded relatively rapidly after excretion, usually disappearing in twenty to twenty-five days. It has been used to monitor sewage sludge and to detect fecal pollution in live-aboard marinas. In the absence of large marine mammal populations or livestock herds, high concentrations in sediments probably indicates recent human fecal pollution.