“…Very small amounts were lethal when introduced intraperitoneally, intravenously, or subcutaneously, but even large oral doses did not cause death. Absorption through the intestine was slow (this has also been observed on humans) (243) and, owing to rapid elimination through the kidney, it was not possible to build up the lethal concentration in the blood. Some indications were obtained of the iron compound being split by intestinal bacteria (20), but no changes were observed with the much more stable ruthenium compound.…”