From time to time, there is media coverage on mercury found in fish. So what is mercury and what is the advice concerning eating fish?

Mercury is a heavy metal that occurs naturally in the environment. It can be released into the air and water as a result of volcanic eruptions and mining activities. Mercury collected in streams, lakes, and oceans can be turned into methylmercury which is readily taken up by living organisms in the water and accumulated up the food chain. Thus large predatory fish, such as swordfish, marlin and some types of tuna, may contain higher level of the chemical.

Since excessive intake of methylmercury can affect the developing nervous system, pregnant women, women planning pregnancy and young children should avoid consumption of large predatory fish. Members of the public are advised to maintain a balanced and varied diet with moderate consumption of a variety of fish as fish is an excellent source of many essential nutrients, such as omega-3-fatty acids and high quality proteins.

Publications and relevant information

Food Safety Focus

• Excessive Mercury in Swordfish Products (Food Safety Focus 99th Issue, October 2014)
• Mercury in Black Cod and Swordfish (Food Safety Focus 51st Issue, October 2010)
• Methylmercury in Shark Fins (Food Safety Focus 36th Issue, July 2009)
• Mercury in Fish and Food Safety (Food Safety Focus 22nd Issue, May 2008)
• Mercury and Food Safety (Food Safety Focus 18th Issue, January 2008)
• Mercury in Seafood (Food Safety Focus 3rd Issue, October 2006)

Pamphlet

• Prevention of Foodborne Diseases in Women -- Planning to Become Pregnant, Pregnant and Lactating

Risk Assessment Study

• The First Hong Kong Total Diet Study : Metallic Contaminants (January 2013)
• Mercury in Fish and Food Safety (April 2008)
• Dietary exposure to Mercury of Secondary School Students (Follow-up Report) (May 2004)
• Dietary Exposure to Heavy Metals of Secondary Students (October 2002)

Risk in Brief

• Risk of Mercury in Fish (February 2011)