Animal Waste, Water Quality and Human Health

330Animal Waste, Water Quality and Human Healthpresent in a number of beverages, including coffee, tea, soft drinks and manypharmaceutical products (Scott et al. 2002). It is excreted in the urine of thosewho have ingested it. Although it requires expensive equipment to detect,degrades fairly rapidly within the environment and is naturally occurring insome plant species, caffeine has been suggested as an indicator of humansewage in surface waters due to its sensitivity (Burkhardt 1999, Hagedorn2001). A recent study in Singapore demonstrated the usefulness of caffeine as achemical marker for detecting human-source contamination (Wu et al. 2008).Coprostanol is a faecal stanol, formed during the catabolism of cholesterol,present in the gut of humans and other animals. It is the primary stanol detectedin domestic wastewater (MacDonald et al. 1983). It has also been proposed as achemical indicator of sewage due to the presence of human specific variants(Chan et al. 1998, Edwards et al. 1998, Nash et al. 2005, Hagedorn & Weisberg2009, Sullivan et al. 2010), in spite of its detection costs, sensitivity issues andnon-anthropogenic sources.Optical brighteners are chemical whitening agents added to many dishwashingand laundry detergents. Detection of these compounds in surface waters, usingtheir ability to fluoresce under ultraviolet light, is simple, fast, and low-cost incomparison to caffeine and coprostanol. Although the detection of opticalbrighteners is complicated by fluorescence from humic acids and other organicmaterials that are naturally present in certain waters (Dixon et al. 2005,Harwood et al. 2005, Hagedorn & Weisberg 2009), this test has beensuccessfully employed in determining the presence of human wastes in severalenvironmental studies (Hagedorn 2001, Hagedorn et al. 2003, McDonald et al.2006).Tracking dry weather discharges from stormwater outfalls and other sourcesmay require the use of field surveys, source attribution techniques or thechemical tracers previously mentioned due to the likelihood of a multi-sourcecomposition. Chemical observations can be made to support the quantificationof the approximate components of a mixed discharge, using a variety ofphysico-chemical indicator parameters including: chlorine, conductivity,detergents, fluoride, pH, turbidity, copper, phenols, and others (Brown et al.2004, Pitt 2001). While all may be employed, it is often necessary to utilizeonly a small subset when investigating the potential for illicit discharges,realizing that not one is perfect (Brown et al. 2004). Each community mustdetermine which combination of chemical indicators works best, based on localconditions and potential discharge types. Although they are not chemicalparameters, testing for indicator bacteria such as E. coli and enterococci inconjunction with chemical testing is likely to enhance the overall capability totrack sources of sanitary sewage (Pitt 2001).