Dynamics of Dioxins : Distribution and Fate of PCDD/DF in Matsuyama Plain.

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The polychlorinated dibenzo-p-dioxins (PCDDs) and dibezofurans (PCDFs) have been found to be ubiquitos in our environment today. They have been in the scientific and general interest for decates, and our country has introduced a few regulations to reduce the release of these compounds in the environment. However, to our knowlege no information is abailable regarding the levels of PCDDs/PCDFs and the sourcese in our environment.We show one of this research results in this year. A result of this study was to find the bioaccumulation of non 2378-substituted PCDFs in fishes in a few ponds in Matsuyama plain. Fish samples are large-mouth bass (Midropterus salmoides) and blue-gill (Lepomis macrochirus). These were divided into the edible parts and internal organs.For the PCDFs, several 2378-substituted and non 2378-substituted isomers were detected in all fish sampls in ponds in Matsuyama plain.In this study, we confirmed that a lot of non 2378-substituted isomers existed in the edible parts of fishes. If various non 2378-substituted isomers exist in the fishes on the market, humen would been exposed to these compounds. We suggest that the risk assesment should be perfirmed for not only 2378-substituted isoners but also non 2378-substituted isomers, in particularly next predominant toxic compounds.Now, we are analyzing other environmental samples (soils, waters, plants and area) which were collected during two years from Matsuyama plain.