In order to assess human health risks associated with chemical or microbiological hazards in recreational or drinking water, we need to have information on the frequency and magnitude of human contact with these water types, as well as information on the water types themselves. Human physiological and behavioural aspects that help to define exposure to hazards are referred to as exposure factors. While understanding exposures is essential when assessing risks, it must be remembered that managing risks needs to protect the whole population not just the 'average' consumer.
This paper reports on selected water-related exposure factors for New Zealanders, derived through a Ministry of Health-funded project to develop exposure factors for assessing the risk from hazardous substances and products. In particular, information will be provided on how much drinking-water New Zealanders ingest and what specific beverage classes contribute most to drinking-water ingestion, based on detailed dietary recall information from national nutrition surveys. In the home, residual microbiological risks may be influenced by thermal treatment of water (boiling) and the changing patterns of hot and cold water ingestion with age will be discussed. While children predominantly ingest non-thermally treated water, about 50% of water ingested by adults has been boiled.
Information will also be presented on recreational water activities New Zealanders engage in and the estimated amounts of water ingested through some of these activities. These activities include primary contact recreation activities (swimming, surfing) and secondary contact activities (boating, fishing).