Japanese officials and experts said Thursday they had little concern about the nation's passion for tuna after revelations in New York of dangerous mercury levels.
The New York Times said Wednesday that laboratory tests conducted for the newspaper showed that eight of 44 sushi pieces bought in the city had mercury levels above the legal limit.
Amid a global craze for Japanese food, the newspaper warned that "a regular diet of even two or three pieces a week at some restaurants could be a health hazard for the average adult," based on US environmental guidelines.
But Japan, which eats a quarter of the world's tuna, said it does not plan to review advice to the public.
Japan's health ministry only advises that women believed to be pregnant limit bluefin tuna consumption to 80 grams (2.8 ounces), or about five pieces of tuna sushi, per week.
"We encourage pregnant women to limit the amount of tuna they eat, but it should not be a problem for the average adult to eat tuna so long as it's a sensible amount," a health ministry official said on customary condition of anonymity. "We will go with the standard for now."
The New York Times reported some tuna samples had mercury in excess of one part per million, the level for the US Food and Drug Administration to take action on the market.
According to the Japanese Fisheries Agency, which conducted research on mercury levels of fish in 2004, an average 0.68 ppm of mercury was detected after testing 60 samples of naturally grown and 30 farm-raised bluefin tuna.
"Mercury concentrations differ in various part of tuna meat," noted Junichi Kowaka, director of the Japan Offspring Fund, a non-governmental consumer group.
For example, the red meat of tuna tends to contain less mercury than the more fatty "toro" part, which is more expensive and popular among sushi lovers.
Kowaka, who described himself as usually critical of the Japanese government's food safety standards, was calm.
"It would be different if we saw damage to consumers, but there haven't been any reports on disorders due to tuna consumption," he said.
"Considering that Japanese people's diet heavily relies on fish, I have to say the safety standard is still appropriate," he said. "At least I'd eat tuna if I have sushi for dinner tonight."