Polychlorinated dibenzo-p-dioxin and dibenzofuran concentrations in serum samples of workers at an infectious waste incineration plant in Japan

In 1998-2000, concentrations of summed polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the exhaust gas of an infectious waste incineration plant were 17-510 ng toxic equivalents (TEQ)/m(3), which reached levels above the Japanese legal limit value of 80 ng TEQ/m(3). The incinerator ceased operation in November 2000. This study was aimed at determining whether the incinerator workers were exposed to high levels of PCDDs and PCDFs. Blood samples of five workers were collected at 1 month and 16 months after the end of the occupational dioxin exposure. For comparison, blood samples were also collected from control subjects. Ash remaining in the incinerator and dust deposited around the conveyer and incinerator areas were collected; TEQ values were 44 and 10 ng TEQ/g, respectively. A month after the end of occupational dioxin exposure, mean TEQ for the workers was 49.1 pg TEQ/g lipid, which was 2.7 times as high as that for the controls. At 16 months, the mean TEQ for the workers decreased to 29.4 pg TEQ/g lipid, which was 1.6 times that for the controls. Ratios of serum level of each congener of PCDDs and PCDFs between 1 and 16 months after exposure were 0.44 to 0.69. This study showed that the serum dioxin levels for the infectious waste incinerator workers were higher than the controls, and the serum dioxin level decreased after the end of the occupational dioxin exposure.