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Wednesday, Sept. 23, 2009
Mercury danger in dolphin meat
SAPPORO — The annual dolphin hunt in Taiji, Wakayama Prefecture, as documented in the film "The Cove" has sparked an emotional international debate, with animal rights activists decrying the capture and slaughter as unnecessary and cruel, and those in Japan who defend the slaughter as both legally permissible under international treaties and an ancient tradition.
But for Tetsuya Endo, a professor at the Health Sciences University of Hokkaido, there is a far more important issue related to the hunt that the public and the government must address.
Dolphin and whale meat is high in mercury, and Endo, one of the world's foremost authorities on mercury levels in dolphins and whales caught off Japan's coastal waters, has discovered Taiji residents who eat the meat sold in local stores have extremely high concentrations in their bodies.
"Between December 2007 and July 2008, myself and a team of scientists and researchers took hair samples from 30 male and 20 female residents of the Taiji area. In three cases, the levels of mercury present were more than 50 parts per million, high enough that it was possible nerve damage, like that seen in victims of Minamata disease, could occur," Endo told The Japan Times in an interview last week.
Endo's tests revealed that one Taiji man in his 50s had a mercury level of 67.2 parts per million. The average mercury level of all 50 subjects was 21.6 ppm for the men and 11.9 ppm for the women.
The average level of mercury present in Japanese people as a whole is only 2.55 ppm for men and 1.43 ppm for women, which means Taiji residents had mercury levels about 10 times the national average.
Meat from pilot whales is quite common in Taiji area stores, and hair samples taken from people who said they ate pilot whale meat more than once a month had an average mercury level of 25.6 ppm, while those who ate the meat once every few months had an average level of 15.5 ppm.
"We discovered that people weren't eating whale meat every day. At most, they were eating it a few times a month. The problem is that although the frequency of eating the meat was low, the levels of mercury in the meat were surprisingly high," Endo said.
Three of the subjects agreed to stop eating whale meat after learning their mercury levels were high.
By the time Endo's study was concluded in July 2008, their levels of mercury had dropped considerably.
The revelation that Taiji residents who ate whale and dolphin meat had high levels of mercury was not a surprise to Endo, as previous testing showed that the meat had far higher levels than the government standard for fish in general.
Between 2002 and 2006, Endo led a team that purchased 60 different samples of whale and dolphin meat in Taiji and neighboring Nachikatsuura.
"The tests showed that the average levels of mercury and methyl mercury in the pilot whale meat bought in Taiji were 9.6 ppm and 5.9 ppm, respectively. Given that Japan's standards are 0.4 ppm and 0.3 ppm, respectively, these are extremely high levels," Endo said.
The standards are based on what is known as the provisional tolerable weekly intake of mercury. Prior to 2003, the international standard was 3.3 micrograms per kg of body weight per week. Based on these numbers, the government established provisional levels of total mercury in fish and shellfish at 0.4 ppm and methyl mercury at 0.3 ppm.
But taking into account the possible effects on pregnant women and children, the World Health Organization revised the 3.3 figure downward to 1.6 micrograms per kg of body weight per week in 2003. Japan, however, adopted a standard of 2.0 micrograms per kg of body weight per week, saying that as a fish-eating culture it is only natural its standard be slightly higher.
The tests on the 50 residents as well as the whale and dolphin meat findings have been made available to Wakayama Prefecture, which is now carrying out further tests. But although Taiji is now the center of international attention, Endo's studies on whale and dolphin meat showed that it was Okinawa, not Taiji, where the highest levels of mercury were found.
"In 2001, meat from a false killer whale that was being sold in Nago had 81 ppm of total mercury (mercury plus methyl mercury) present," Endo said.
Asked why the government doesn't do more to warn consumers of the possible dangers of eating whale and dolphin meat, such as putting warning labels on all meat sold, Endo says it's likely that officials simply don't see a problem.
"The official attitude is probably along the lines of because so few people eat dolphin and whale meat, and since they tend to be mostly older, it's not that big of an issue," he said.