Comparison of PCDDs and PCDFs in the tissues of Yusho patients with those from the general population in Japan and China

Human tissue samples from (i) China, (ii) Japan and (iii) two Japanese Yusho patients were analyzed for PCDDs and PCDFs. Chinese adipose tissue contained the lowest residue with PCDF concentrations similar in many cases to PCDDs and less than 30 pg/g. Levels and patterns of PCDDs and PCDFs in Japanese adipose tissue were similar to those found in other industrialized countries such as North America and Europe. Samples of tissue from a Yusho patient nine years after exposure contained about 50 times more of the toxic PCDF isomers than current Japanese tissues at a concentration which was still near that associated with an adverse effect. The remarkable persistence of PCDFs in humans was further illustrated by the finding of elevated levels of PCDFs in a specimen of uterus tissue some 17 years after exposure to the toxic Yusho oil.