(ASAHI) "Dioxins affect on dolphins and whales. Found higher concentration around Japan compared to the southen ocean. Research by Ehime Univ."
A group led by Prof. Wakimoto, School of Agliculture, Ehime Univercity, Japan, found higher concentrations of dioxins in bodies of Japanese coastal dolphins and whales than the ones in the southen ocean. The comparison of concentration levels was made internationally for the first time. Since the type of dioxins found in cetacean bodies were the same as those found in burnt garbage, Prof. Wakimoto thinks that dioxin pollution by burnt garbage has increased. As the human body takes up dioxins mostly from foods such as fish, the contamination of Japanese coastal whales seems to affect the Japanese diet.
Since whales and dolphins are located in the higher levels of the food chain, the whole picture of oceanic pollution can be only understood by examining dioxin levels of cetacean bodies. Prof. Wakimoto's group examined dioxin levels in the blubber of 23 bodies of cetaceans including Baird's beaked whales and Fraser's dolphins off Nagasaki and Wakayama, Japan and 16 of Fraser's dolphins and Spinner dolphins around the Phillipines and the Indian Ocean.
When the toxicity of the different dioxins were expressed as those of 2,3,7,8-TCDD, that is one of the most toxic substance, 0.03~1.2 pico gram from the bodies of the southern cetacean were found, while 0.6~18.2 pico gram were found from Japanese bodies. Strikingly, the dioxin levels of 8~80 times higher than those of southern coastal ones were found from three Japanese coastal Finless porpoises. Dioxins are comprised of 75 isomers of dibenzo-para-dioxins and 135 of dibenzofurans. Isomers from both dibenzo-para-dioxins and dibenzofurans were found in the bodies of Japanese coastal cetaceans but almost no isomers of dibenzo-para-dioxins were found in the southern bodies. Burnt garbage produces both types of isomers and Prof. Wakimoto suspects that
Prof. Wakimoto warned,"There are many garbage burning facilities in Japan and the regulations are poor, letting pollution on the land extend to the sea. We assume that the dioxin from Japanese land hasn't reached offshore waters, but have to take appropriate mesurements as quick as possible since chemicals in the envi ronment always spread."