Distribution of radioisotopic beryllium in mice after administration by various routes of injection.

A 7BeCl2 solution containing 0.5 micrograms Be per mouse was injected subcutaneously, intraperitoneally, intramuscularly, intrathoracically, and intravenously, and distribution was observed for periods up to 1 wk. 7Be was excreted more rapidly following intravenous injection than by the other routes of injection. The amount of Be found in the liver or the spleen was substantial at 1 d after intraperitoneal injection. It increased more in the spleen at 7 d after either intraperitoneal or intrathoracic injection. On the other hand, the amounts of Be stayed almost constant in the kidneys, by the various routes of injection. When injected intrathoracically, the amounts of Be in the heart and the lung were greater than when administered by the other routes of injection. The amounts of Be in the femurs of mice administered by these routes of injection, except with intravenous injection, were greater than in the other organs. The percentage of 7Be in the mineralized bone was 90% of that of 7Be in the femurs when injected intraperitoneally or intrathoracically. However, the ratio of Be in the mineralized bone to that in the bone marrow was 3 to 2. Beryllium had thus a closer affinity for the femurs than for the other organs investigated, with the different modes of administration used. The amount of Be in the entire skeleton was estimated to be substantial. Within the limitations of 1 wk of exposure, the skeleton would appear to be a critical organ. This would suggest that osteosarcomas may occur following administration of Be to laboratory animals for a long-term period.