Local tuna, salmon sashimi found with excessive mercury levels

April 16, 2019 14:37
The Consumer Council said the amount of mercury in 10 of the 19 tuna samples from local outlets was found to have exceeded the statutory limit. Photo: HKEJ/Bloomberg

The Consumer Council has issued a warning on fresh tuna and salmon sold in Hong Kong markets, saying tests showed that nearly all of the samples were contaminated with mercury, some with levels in excess of the legal limit, the Hong Kong Economic Journal reports.

Trying to find out if sashimi products sold locally are safe to consume, the council collected 50 samples, including 31 salmon and 19 tuna meat slices, from supermarkets, takeaway outlets and restaurants between December 2018 and February this year.

Revealing the test results on Monday, the consumer watchdog said 49 of the 50 samples contained the heavy metal methylmercury, which is an organic compound of mercury.

Under the Food Adulteration (Metallic Contamination) Regulations, the legal maximum level for mercury, including methylmercury, in food is 0.5 part per million (ppm).

According to the council, the amount of mercury in 10 of the 19 tuna samples was found to have exceeded the statutory limit, with a sample from a Tsuen Wan branch of a sushi chain found having 1.48 ppm and a sample from a mini-supermarket in Wan Chai found having 1.23 ppm.

For salmon samples, all except one were found to have methylmercury, although none exceeded the limit.

Mercury can harm a person's nervous system, the council said, adding that pregnant women and young children, in particular, should avoid eating too much fish which could be tainted.

Professor Tam Wing-hung from the Hong Kong College of Obstetricians and Gynecologists said it could take more than a year for the human body to completely rid itself of methylmercury, and advised women planning to get pregnant to quit eating food high in methylmercury at least one year before becoming pregnant to avoid harming the fetus.

In addition to mercury, the council also found roundworms and worm eggs in one tuna sample from a chain sushi restaurant in Tai Koo and roundworms in one salmon sashimi sample from a shop in Tsuen Wan, although it could not confirm if they were still alive as they were not moving.

The two restaurants where the samples were collected disagreed with the results, claiming that food safety is the first thing to consider and that all of their products had passed tests hygiene and safety conducted by the Food and Environmental Hygiene Department.

The department said it has followed up on the results on-site at the two places and no irregularities were detected.

Meanwhile, Professor Nora Tam Fung-yee, who chairs the Consumer Council’s research and testing committee,called on the public to abandon the misconception that some condiments including mustard, saltwater, lemon juice and garlic, which are only in contact with the sashimi for a short period of time, can help kill bacteria contained in sashimi products, adding that such belief was not substantiated by scientific evidence.

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