Rate of decrease and half-life of polychlorinated biphenyls (PCBs) in the blood of mothers and their children occupationally exposed to PCBs

Long-term studies on the concentrations of polychlorinated biphenyls (PCBs) in the blood of children and their mothers occupationally exposed to PCBs were made during the period 1975 to 1979. This report deals in particular with the rates of decrease and half-lives of PCB concentrations in the blood. Rates of decrease of the concentration of PCBs in the blood of both mothers and their children were relatively constant and independent of PCB concentrations. Therefore, a one-compartment model equation was sufficient to represent the decrease of the concentrations of PCB in the blood. The mean rate constant of the decrease of PCB concentration for the children was approximately 2.6 times higher than that of the mothers.The dilution effect due to the increase of body weight was the most important factor which affected the reduction of the PCB concentrations in the children. Since the rate of the body weight gain is very high during the two years after birth, the half-life of the PCB concentration was extremely shortened during this period. The natural excretion of PCBs from children was estimated to be about 10%, which was obtained by subtracting the rate of decrease of PCB concentration by the dilution effect, due to the gain of body weight from the total rate of decrease per year. This rate constant relates favorably to that of the mothers.

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