Wednesday, 18 May 2016

SPHPM researchers develop a novel method of tracing inadvertent water ingestion

Two new studies published by Senior Research Fellow Martha Sinclair and colleagues in the Infectious Disease Epidemiology Unit at SPHPM have devised a methodology for testing inadvertent non-potable water ingestion, using cyanuric acid (CYA) in urine as a chemical ‘tracer’. The studies were a collaboration with the School of Civil, Environmental and Chemical Engineering at RMIT.

Non-potable water is water that is not of drinking quality, such a grey water, rain water or recycled water but may still be used for other purposes.

Dr Sinclair’s latest studies have developed a method that could be applied to a range of non-potable water use activities; in order to generate exposure data for risk assessment processes to ensure ingestion exposure of non-potable water is well understood and adequately managed to protect public health.

CYA is commonly used in chlorinated pools to prevent the chlorine from decomposing in ultra violet light, and the human body can safely ingest small amounts. CYA can be detected in urine for 24 hours post ingestion, and therefore is a novel method of tracing inadvertent water ingestion.

Dr Sinclair and her team of researchers did just that, first validating whether this test was capable of measuring excretion of CYA, and then in another study recruited participants to simulate washing a car using water containing CYA. This test was to see whether CYA tracer could be found in their urine, and at what levels, as a result of spray exposure.

Dr Sinclair’s studies have important public health implications —currently regulatory agencies and industry rely on “expert guesses” says Dr Sinclair, in order to assess potential health risks from
non-potable water supplies.

“Our results demonstrate the capability of this method and that it could be employed in the future to produce empirical data for a range of water using activities, and it may also be useful to assess proposed new applications for non-potable waters,” Dr Sinclair said.

Almost 70 per cent of participants had quantifiable amounts of CYA in their urine, and the lowest quantified value was higher than could be attributed to absorption through the exposed skin of the face, which means that inadvertent ingestion or inhalation likely occurred in all participants.

“The data obtained from this study suggest that protective equipment may be required for workers in order to reduce risks of pathogen exposure, as modelling from our data suggests occupational exposure as opposed to domestic exposure is likely to be considerably higher,” Dr Sinclair said.

She added that this supports the view that personal protective equipment to reduce spray exposure to the face is advisable for workers engaged in activities such as vehicle washing and plant wash down on a daily basis. However, the current Australian guidelines for water recycling do not specifically address exposure from high pressure sprays.

Dr Sinclair has been involved in public health research on water related diseases since 1995, with a keen research interest in developing water quality guidelines. Her colleagues on the project included: Professor Felicity Roddick, Dr Stephen Grist, Dr Thang Nguyen, Dr Joanne O'Toole and Professor Karin Leder.

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