Deaths in Rotorua's geothermal hot pools: hydrogen sulphide poisoning

In late 2007 and early 2008 two gentlemen were found dead in, or near to, enclosed hot pools fed with Rotorua's geothermal waters. Amidst much publicity the Coroner has ruled that the deaths were related to hydrogen sulphide poisoning. Following post mortem examinations, blood and urine samples were frozen and sent to the Toxicology Unit of ESR. These were then stored frozen until analysis. Hydrogen sulphide (H(2)S) is a potentially deadly gas at elevated levels, but is rapidly eliminated from the body and is unstable post mortem. Thiosulphate is a marker for the exposure to H(2)S, and as it is stable post mortem the samples were analysed to determine the thiosulphate levels present. The urine thiosulphate levels detected were above those seen in the urine samples measured from the only previous study of people exposed to the Rotorua thermal area and the blood levels were similar to literature values from fatalities exposed in workplaces such as sewage treatment plants.