Dall’s porpoises, inhabiting polluted coastal
waters, have long been known to carry high levels
of a range of pollutants, including mercury (Hg).
Based on 1972 World Health Organisation (WHO) recommendations,
Japan’s Health Ministry (JMHLW) sets a consumption
limit (PTWI) of 170µg of methylmercury (MeHg)
in a 50 kg person per week and blanket maximum contamination
levels in seafood products of 0.3 µg/g (parts
per million – ppm) MeHg and 0.4 ppm Hg. In 2003
the WHO revised their PTWI for MeHg down by half,
to 1.6 µg/kg-body weight, to protect against
neurodevelopment disorders in the fetus. The JMHLW
has made no revisions to their general advisory levels
in response to this advice, however the PTWI for pregnant
women has been revised to 0.2 µg/kgbw MeHg.
There is no enforcement of the blanket limits of
0.4ppm mercury and 0.3 ppm methylmercury, which are
exceeded in almost all small cetacean meat and blubber
products found on sale in Japan, including Dall’s
porpoises. A study published in August 2005 analysed
160 samples of small cetacean products sold on Japanese
markets for human consumption, including 9 samples
of Dall’s porpoise meat. The average MeHg concentration
over all Dall’s porpoise samples was 1.02 µg/g,
almost 3½ times the recommended limit set by
JMHLW. According to the WHO’s 2003 assessment,
a 50 kg person could eat no more than 78 g of Dall’s
porpoise meat per week without risking mercury poisoning.
A 2006 EIA survey of cetacean products in Japan found
high levels of cancer-causing PCBs in Dall’s
porpoise blubber. The blubber contained 4 ppm PCBs,
eight times more than regulatory limits allow and
the most PCB-polluted product out of 67 products sampled
in 2006 and 2007.
Independent DNA analyses have shown that Dall’s
porpoise meat is sold as ‘whale meat’
in canned and processed products, and as fresh ‘whale
meat’ in fish markets around the country, including
Tokyo. Mislabelling of dolphin meat as whale meat
is a direct infringement of Japanese law, however
enforcement is non existent. The reason for this illegal
trade is simple: sold as whale, Dall’s porpoise
meat will fetch up to ten times the price for sale
as porpoise meat.
Report (2008): Poisonous Policies.
Japan’s failure to stop the sale of polluted
whale, dolphin and porpoise products.
Report (2003): Mercury Rising:
The sale of polluted whale, dolphin and porpoise meat
Report (2008): Poisonous Polices – Japanese