2011-2012 Microcystins and Nodularin in Bottled Water
The Food Safety Action Plan (FSAP) aims to modernize and enhance Canada's food safety system. As a part of the FSAP enhanced surveillance initiative, targeted surveys are used to test various foods for specific chemical and microbiological hazards.
The main objective of this targeted survey was to generate baseline surveillance data on the microcystin and nodularin levels in bottled water available on the Canadian retail market.
Cyanobacteria, also known as blue-green algae, are commonly found in surface water algae blooms or blue-green scums. Cyanobacteria can produce hepatotoxins, of which microcystins and nodularin are the most common cyanobacterial toxins found in water. The presence of microcystins and/or nodularin in water may result in an unpleasant taste and odour, and may cause illness in people consuming these toxins. It is also possible that extended exposure to low levels of these cyanobacterial hepatotoxins may have long-term or chronic effects in humans. Microcystins in particular have been identified as a significant threat to freshwater supplies by the World Health Organization (WHO). Microcystins/nodularin may be present in bottled waters available at retail if they are present in the water source used to manufacture the final bottled product and if the water is inadequately treated.
The Federal-Provincial-Territorial Committee on Drinking Water (CDW) has established the Guidelines for Canadian Drinking Water Quality, which are published by Health Canada. The guideline for the maximum acceptable concentration of total microcystins in drinking water is 1.5 micrograms per litre (μg/L). There are currently no guidelines for nodularin in drinking water in Canada.
The 2011-2012 Microcystins and Nodularin in Bottled Water survey targeted domestic and imported bottled water (unflavoured, carbonated and non-carbonated) packaged in plastic and glass bottles. A total of 301 samples were collected from retail stores in 11 Canadian cities between May 2011 and March 2012. Each sample was analyzed for the most commonly-occurring hepatotoxins, specifically, four forms of microcystin and nodularin.
All 301 samples tested did not contain a detectable level of microcystins or nodularin. Thus, 100% of the samples tested were below the Canadian guideline for the maximum acceptable concentration of total microcystins in drinking water. Given that none of the samples in this survey were positive for microcystins, follow-up actions were not deemed necessary.
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