Regional differences in dietary intake of environmental pollutants in Japan

In order to study regional differences in the dietary intake of environmental pollutants in Japan, we measured the daily intake ingested via food (the main route for pollutant intake) and analyzed the data by multivariate analysis. Daily mean samples were collected by the duplicate method from 25 women per area in 5 cities in both northern and southern Japan in July, 1987. Cadmium, lead, benzo(a)pyrene, hexachlorobenzene, DDT, chlordane isomers, and the total amount of the isomers were determined for typical pollutants. The data were statistically analyzed by multivariate analysis. Regional differences in the daily intake of environmental pollutants were studied by discriminant analysis. The eigenvalues of the functions 1 and 2, which accounted for 84.8% of variance, were 0.647 and 0.221, respectively. The function 1 was related to regional differences in the intake of environmental pollutants in the northern and southern regions of Japan. The statistical distance calculated from the intake of environmental pollutants correlated well with the geographical distance. The coefficients of the canonical discriminant function 1 were large in the order of lead (Pb) and the total amount of chlordane isomers (T-CLD). The regional difference was assumed to be due to the intake of Pb in the north and the intake of T-CLD in the south. Other pollutants, however, did not contribute to the observed regional difference. The study shows that performing multivariate analysis by computer provides a useful means for processing a large amount of data and can provide important information for data analysis in environmental health.