BRITISH TOXICOLOGISTS may have found the strongest evidence yet to link the mysterious deaths of porpoises and dolphins from infections with environmental pollution. Peter Bennett and Paul Jepson, of the Institute of Zoology in London, have analysed the blubber of harbour porpoises stranded on the coast since 1990. New Scientist reports they found the average level of PCBs - toxic, man-made chemicals - was 31.1 milligrams per kilogram of blubber in 33 porpoises that had died of infections, against 13.6 a kilo in 34 healthy animals. "PCBs have been shown to damage the immune systems of other mammals in the lab," Dr Bennett said.
A similar study, to be published next year, shows a similar association with mercury found in harbour porpoises' livers. Maybe mercury and PCBs interact.Reuse content