Wastewater often contains endocrine disrupting compounds (EDCs) such as ethinyl estradiol (EE2) which is excreted by women who use some oral contraceptive pills. When wastewater treatment is followed by advanced recycling processes, most of the hormone-like EDCs are removed, but it is possible that these very low levels might still adversely affect health. Giving recycled water to mice will allow examination of these health risks but it is first necessary to develop methods to measure extremely low levels of three forms of estrogen (estrone, estradiol and EE2), as well as progesterone and bisphenol A (BPA), an EDC that leaches out of plastic drinking bottles. This research modified clinical ‘ELISA’ tests commonly used to measure hormones in patient blood samples, and established protocols that allowed the sensitive quantification of five EDCs in recycled water.

This research was prompted by concerns that rooftop-harvested rainwater fed into household hot water services might expose the public to harmful pathogens such as salmonella. Householders can be exposed to untreated heated rainwater while washing and when this water is used to wash or prepare food. Water heated to 60°C and maintained at this temperature for several minutes’ kills most, but not all infectious pathogens. The problem is that many Australian hot water services operate at lower temperatures that do not kill enteric pathogens. In this study fewer than 5% of water samples collected from unheated rainwater tanks contained pathogens, but this relatively low frequency still poses a risk and is part of the reason that heated rainwater systems fail to meet existing guidelines for safety. Modifications that would improve safety include installing a device that prevents water cooler than 60°C leaving the storage tank and using cold potable water instead of cold rainwater for tempering or in mixer taps. UV disinfection devices attached to rainwater systems are an effective way to reduce health hazards to acceptable levels.

This project developed analytical methods sensitive enough to detect the very low levels of compounds that leach out of old coal tar enamel-lined pipes, then catalogued the chemicals and the levels they were found at in a problematic pipeline. One of the chemicals leaching out of the old lining is probably acted on by microbes to produce another substance with an earthy, musty flavour. None of these were toxic in tests and they are therefore unlikely to pose a risk to human health.

Cryptosporidium is a waterborne microscopic parasite with different forms at various stages of its lifecycle. One form, the spherical oocyst, is excreted by infected people and transported in rivers and surface waters. The problem is that it is not known if oocysts found in water are dead or are alive and infectious. This leads to an overestimation of the public health risk posed by oocysts found in source waters.

This research developed an in vitro cell culture test to differentiate between dead and infectious oocysts. The immortalised HCT-8 cell line was derived from cancerous human intestinal cells. When the cells are grown in a culture vessel, they display many characteristics of normal human gut cells. It was discovered that treating oocysts with acid to mimic stomach pH and using centrifugal force to ensure oocysts contact the HCT-8 cells, live (but not dead) oocysts react as though they are infecting a human host. The oocysts ‘hatch’ the next sporozoite form of the lifecycle, and these can be counted using a microscope. This ‘infectivity assay’ gives an improved, more accurate method for quantifying risks to human health presented by unidentified cryptosporidium oocysts in water.