Japan's whale meat exceeds mercury density safety limits

Mercury levels in whales caught in Japan's coastal waters increase the further south the creatures are caught, with one specimen from Okinawa's Nago registering a mercury density more than 57 times the nation's provisional safety limit, according to a group of experts.

Group member Tetsuya Endo, a lecturer at the Health Sciences University of Hokkaido, said that mercury dissolved in seawater may have accumulated in fish and other whale prey along the Black Current, which flows north toward Japan's Pacific coast from east of the Philippines.

The mercury may stem from industrial pollution in Japan and Southeast Asia, as well as from natural sources such as undersea volcanic activity, Endo said.

The group said it will present its findings at a May meeting of the Food Hygiene Society of Japan in Tokyo. Efforts to gain a comprehensive understanding of the problem are only in their infancy as there is no comprehensive data on mercury density in the sea.

The researchers analyzed mercury density in 83 slices of red meat obtained from different kinds of whales, bought from six regions stretching from Abashiri in Hokkaido to Nago between 2000 and 2002.

Every slice exceeded Japan's provisional limit on the maximum density of mercury, which stands at 0.4 parts per million. In Nago, researchers identified an average mercury density of 11.6 ppm.

This was followed by Taiji in Wakayama Prefecture, at 9.8 ppm.

By the time the group worked its way up to Abashiri, which faces the Sea of Okhotsk, the average mercury density had fallen to 0.8 ppm, still double the acceptable limit.

One slice of whale meat in Nago had a mercury density of 23.1 ppm, the highest level recorded by the group.

The researchers also looked specifically into methyl mercury, which damages the nervous system and was responsible for causing Minamata disease in the 1950s and 1960s. The highest level was identified in whale meat from Taiji, at 10.6 ppm, more than 35 times the methyl mercury limit of 0.3 ppm.