The objective of this study was to demonstrate the use of chemical biomarkers (fecal sterols and bile acids) to identify selected sources of fecal pollution in the environment. Fecal sterols and bile acids were determined for pig, horse, cow, and chicken feces. Ten to twenty-six fresh fecal samples were collected for each animal, and the concentrations of fecal sterols (coprostanol, epicoprostanol, cholesterol, cholestanol, stigmastanol, and stigmasterol) and bile acids (lithocholic acid, deoxycholic acid, cholic acid, chenodeoxycholic acid, ursodeoxycholic acid, hyodeoxycholic acid) were determined using a gas chromatography and mass spectrometer (GC-MS) technique. Correlation study was performed among sterol and bile acid variables for selected animals, and a ratio (cholesterol + epicoprostanol)/(deoxycholic acid + chenodeoxycholic acid + hyodeoxycholic acid) has been proposed as an indicator for assessing fecal input. The levels of (cholesterol + epicoprostanol)/(deoxycholic acid + chenodeoxycholic acid + hyodeoxycholic acid) in horse, cow, chicken and pig were observed 3.258±1.191, 1.921±1.006, 1.013± 0.726, and 0.205±0.119 respectively and the ratio of horse: cow: chicken: pig was 16: 9: 5: 1. This ratio suggests the potential of sterol and bile acid biomarkers in identifying sources and occurrence of fecal matter. While additional work using polluted water (as opposed to fresh fecal samples) as well as multiple pollution sources are needed to investigate the transport of these biomarkers into water bodies.

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Nonpoint source pollution is the leading remaining cause of water quality problems. The extent of NPS pollution is often more difficult or expensive to monitor at the point(s) of origin, as compared to monitoring of point sources. This study evaluated the hypothesis that animal manure (chicken, cow, horse, and pig) applied to pasture contribute fecal sterols and bile acids to runoff. The study also assessed the potential benefit of fecal sterols and bile acids as biomarkers in distinguishing fecal pollution and its sources. Fecal sterol and bile acid concentrations were determined in flow-weighted composite runoff samples collected from 2.4×6.1 m plots (n=3) amended with manure. Runoff was generated from simulated rainfall (152 mm.h −1 ). Runoff samples from manure-amended plots showed high concentrations of fecal sterol (ranged from 13±1 to 1,287±183) and bile acid (ranged from 24±1 to 2,251±248) biomarkers. The profiles of fecal sterols and bile acids in runoff samples were similar to those of fresh manure for all selected animals. For runoff and fresh manure, chenodeoxycholic acid, deoxycholic acid, epicoprostanol, and hyodeoxycholic acid were consistent biomarkers for chicken, cow, horse, and pig, respectively, suggesting that sterols and bile acids can be used to identify sources and occurrence of fecal matter in water and sediments.

This review paper discusses some of the earlier and current methods used to identify the human and non-human sources of fecal pollution in water. It is mainly focused on chemical approaches, i.e., fecal sterol and bile acid biomarkers, to identify the sources of fecal pollution. Findings of our study are in agreement with earlier investigations, that it is unlikely for any single determinant to be useful in all situations but a multiple biomarker approach or statistical analysis of microbial and chemical determinants offer the possibility of identifying and apportioning human and animal fecal inputs to natural waters.Keywords: bifidobacteria; bacteriophages of bacteriodes; fecal sterols and bile acid; FC/FS ratio; F-specific RNA coliphages; human enteric viruses.Reference to this paper should be made as follows: Tyagi, P., Edwards, D.R., and Coyne, M.S. (2009) 'Distinguishing between human and animal sources of fecal pollution in waters: a review', Int.

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