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.

EIA Report (2008): Poisonous Policies. Japan’s failure to stop the sale of polluted whale, dolphin and porpoise products.

EIA Report (2003): Mercury Rising: The sale of polluted whale, dolphin and porpoise meat in Japan.

EIA Report (2008): Poisonous Polices – Japanese translation