Female mice on gestational day 17 were injected intravenously with a single dose of54Mn or65Zn solution, and organ distributions of these radionuclides in the fetuses were studied 3, 6, 24 and 48 hours after administration using gamma counting and macroautoradiography. The fetuses of a litter incorporated 19% of the administered54Mn and 50% of the administered65Zn in the uterus. The pancreas showed the highest concentration of54Mn in fetuses, followed by the gastrointestinal tract, kidneys and liver. 54Mn distribution pattern in fetuses was similar to that in dams, but the uptake in the bone and brain seemed to be greater in fetuses than in adults. 65Zn was markedly accumulated in the fetal liver, while no detectable amount of65Zn was found in the brain. Although fetal distribution of65Zn was similar to maternal one, 65Zn concentrations in fetal tissues were generally higher than those in dams.
The air pollution caused by CO2from fossil fuel origin was quantitatively studied by radiocarbon (14C) measurement on the samples of new leaves taken from roadside trees. In the area where concentration of CO2 (12CO2+13CO2) of fossil fuel origin was high, the count of β-ray radiation from14C tended to be low. The relation between the concentration of sulfur dioxide (SO2) in the air and the count of β-ray radiation from the leaf samples could be represented by a linear regression, Y= (17.568/X) -67.385; r = -0.995 Where Y is the SO2concentration in ppb and X is the β-ray radiation count (Bq/g-carbon) .