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Norovirus & Marine Water Contamination

Norovirus contamination in BC's marine environment has led to instances of foodborne illness. A working group has reported on causes, and provided examples of other risks to the safety of marine waters.
Working group reports

Norovirus illness in raw oyster consumers was investigated by a working group chaired by BCCDC Environmental Health in 2017. Many agencies participated in this working group, including industry, academia and representatives from regional, provincial, federal and international regulatory and health agencies.

The working group concluded there were several transmission routes of norovirus into the marine environment. All originated from human sewage sources. The working group also concluded that environmental conditions in 2016 and 2017 allowed norovirus in sewage sources to survive and reach shellfish farms.


Supporting documents

Marine sewage discharge requirements for vessels

Posted with permission of Transport Canada. Locations of pump-out stations may be found on our Shellfish Harvesting Map.

Public health notices 

Examples of hazards

Marine waters can be negatively impacted by human activities. Marine water contamination risks include chemical hazards, radiation, and physical and microbiological hazards. 

Chemical hazards

Fuel spills: Oil and fuel leaks from marine vessels contaminate the marine environment and are a concern when food sources and marine animals are affected. 

Sunscreen: Swimmer pollution from sunscreen and suntan lotion is known to damage coral reefs. Chemicals such as zinc oxide, found in sunscreen, cause bleaching. 


Iodine-131, Cesium-134, Cesium-137: A massive earthquake and tsunami in Japan in March 2011 caused the nuclear power plant in Fukushima to fail. Several radioactive isotopes were released into the marine environment from nuclear fuel leaks. 

Acoustic waves & sound: Marine mammals including southern resident killer whales are negatively impacted by the sounds of commercial and recreational vessels. 

Physical hazards

Debris: A massive earthquake and tsunami in March 2011 washed out structures in Japan. Debris from the event was found on North American coastlines several years later.

Plastics, microplastics & garbage: There are an estimated five trillion pieces of plastic floating in the sea, a major source of pollution. Plastics and microplastics are found in marine species and have been found in our foods. 

Microbiological hazards

Norovirus: Norovirus is the most common foodborne illness in Canada. Over one million people (1 in 8) become ill with foodborne norovirus every year. When human sewage enters the marine environment it can contaminate our food supply. This has caused several outbreaks of norovirus in recent years.

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