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Trace Elements in Abiotic and Biotic Environments
31.3 HUMANS
The total amount of Os in the human body is not known and has no significant
biological role. Although the metal itself is not toxic, its volatile oxide is (Emsley
2011). Osmium tetroxide (OsO 4 ) is extremely poisonous and highly volatile; penetrates the skin readily; and is very toxic by inhalation, ingestion, and skin contact.
Airborne low concentrations of OsO 4 vapor can cause lung congestion and skin
or eye damage, and should therefore be used in a fume hood (Luttrell and Giles
2007).
Its particles can cause damage to the mucus membranes, because they act as an
irritant. Prolonged exposure to the dust can damage the lungs. Concentrations of OsO 4
in air, as low as 10 −7 g/m −3 , can cause lung congestion, skin damage, and severe eye
damage.
The toxicity of OsO 4 in food is rapidly reduced to relatively inert compounds, by
polyunsaturated vegetable oils, such as corn oil.
Osmium carbohydrate polymers, called osmarins, have been synthesized and proposed for use as active agents to treat arthritis. This proposal was based on the use
of OsO 4 for about 50 years to treat human arthritis and cancer, mostly in Europe.
However, this treatment is controversial because of the high toxicity of OsO 4 , which
is injected (in solution) into the synovial space of diseased joints. Osmium-containing
material remained in the joints for as long as 5 years, suggesting a long-term biological effect. The use of the Os carbohydrate polymers for this purpose was proposed
to avoid trauma associated by unselective OsO 4 oxidations. Unlike the highly toxic
OsO 4 , the osmarin polymers have low acute toxicities (Carraher and Pittman 2004).