USING FECAL STEROLS FROM HUMANS AND ANIMALS TO DISTINGUISH FECAL POLLUTION IN RECEIVING WATERS

The sterol content of faeces from humans and 14 species of animals com mon to rural or urban environments were examined. The major human faec al sterol was the 5 beta-stanol, coprostanol which constituted approxi mate to 60% of the total sterols found in human faeces. The sterol pro files of herbivores were dominated by C-29 sterols and 5 beta-stanols were generally in equal or greater abundance than 5 alpha-stanols. The principal faecal biomarker of herbivores was 24-ethylcoprostanol. The sterol content of bird faeces was extremely variable and largely depe ndent on the animals diet. Both 5 beta and 5 alpha stanols were in ver y low abundance in birds and dogs faeces from this study presumably du e to the absence or low activity of the necessary anaerobic biota requ ired to reduce Delta(5)- or Delta(5,22)-sterols to stanols. Cats and p igs were the only animals that had similar faecal sterol profiles to h umans. However, the concentration of the principal human biomarker cop rostanol was some 10 times more abundant on a dry weight basis in the faeces of humans than in those of cats and pigs. The source specificit y of faecal sterol biomarkers is a combination of sterol intake, metab olic production of sterols and the biota resident within the animal's digestive tract. The ''sterol fingerprints'' of the faeces of humans a nd animals are sufficiently distinctive to be of diagnostic value in d etermining whether faecal pollution in water samples are of human or a nimal origin. Copyright (C) 1996 Elsevier Science Ltd