Hong Kong watchdog: mercury, worms in sashimi

The Hong Kong Consumer Council has announced in a press release that 49 out of 50 samples of sashimi (raw fish) it tested were contaminated with sometimes excessive amounts of mercury.

The watchdog said on Monday that it tested 19 tuna and 31 salmon sashimi samples from restaurants, supermarkets and takeaway outlets in Hong Kong and found that all but one contained methylmercury, an organic compound of the heavy metal, according to the press release.

In 10 of the 19 tuna samples, the amount of mercury was nearly double Hong Kong’s safe limit.

Mercury is harmful to the body’s nervous system, particularly the developing brain, so pregnant women, women planning to become pregnant and young children should avoid eating fish that may contain high methylmercury levels, particularly big or predatory fish species.

Meanwhile, the roundworm parasite was found in one tuna sample from Genki Sushi in Tai Koo and in one salmon sample from Uo-Show in Tsuen Wan. The tuna sample from Genki Sushi also had worm eggs.

Eating raw or undercooked marine fish may expose diners to the risk of Anisakis, a type of roundworm infection causing symptoms such as abdominal pain, nausea and vomiting within one to 12 hours.

According to the Codex Alimentarius Commission’s Code of Practice for Fish and Fishery Products, fish served raw must first be treated with a specific freezing process (at -20°C for 7 days or -35°C for 20 hours) to kill parasites, which has the same effect as cooking food thoroughly.

According to Gilly Wong Fung-han, the council’s chief executive, adding wasabi, vinegar or lemon juice or torching sashimi would not kill roundworms.

Genki Sushi and Uo-Show disagreed with the test results, saying their ingredients have always passed the Food and Environmental Hygiene Department’s food safety tests.