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Tests on whalemeat
on sale in Japan have revealed astonishing levels of mercury.
While it has long been known that the animals accumulate heavy
metals such as mercury in their tissues, the levels discovered
have surprised even the experts.
 Two
of the 26 liver samples examined contained over 1970 micrograms
of mercury per gram of liver. That is nearly
5000 times
the Japanese government's limit for mercury contamination,
0.4 micrograms per gram.
At these concentrations,
a 60-kilogram adult eating just 0.15 grams of liver would
exceed the weekly mercury intake considered safe by the World
Health Organization, say Tetsuya Endo, Koichi Haraguchi and
Masakatsu Sakata at the University of Hokkaido, who carried
out the research. "Acute intoxication could result from
a single ingestion," they warn in a draft paper accepted
for publication in The Science of the Total Environment.
The researchers
call on the government to impose tighter regulations on the
consumption of whale organs. In particular, they warn that
pregnant women risk poisoning their unborn children. In the
1950s and early 1960s, hundreds of children around Japan's
Minamata Bay were born with horrific birth defects after their
mothers ate seafood contaminated with mercury compounds, which
had been poured raw into the bay since the 1930s. Thousands
more suffered brain damage.
Single
Mouthful
Even veteran researchers
from the Minamata saga were shocked by the new figures. "Hirokatsu
Akagi, a director of the National Institute for Minamata Disease,
was very surprised," says Endo. "He'd never seen
levels above 20 micrograms per gram."
On average, concentrations
of mercury in whale and dolphin livers were 370 micrograms
per gram, 900 times the government limit. Average levels in
kidneys and lungs were also high, about 100 times the limit.
None of the samples was below the limit.
In work not yet
published, Endo's team has shown that rats suffered acute
kidney poisoning after a single mouthful of the most highly
contaminated liver. While levels were lower in muscle, Endo
told New Scientist that on average it still contained 2.5
to 25 times the limit.
The samples came
from small-toothed whales and dolphins, catches of which are
not restricted by the International Whaling Commission, the
international body that regulates whaling. Mercury becomes
concentrated in their internal organs when they eat contaminated
fish and squid.
New
Scientist June 6, 2002
The
Science of the Total Environment
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