As a subject matter expert in chemistry, I can tell you that osmium, with the chemical symbol Os and an atomic number of 76, is a hard, brittle, blue-gray or blue-black transition metal in the platinum group. It is found as a minority component of the naturally occurring alloy platinum or as a trace element in the Earth's crust.

Osmium is not considered toxic in its elemental form. However, like many heavy metals, it can be toxic in certain compounds. For instance, osmium tetroxide (OsO4) is a highly toxic compound and is known for its use as a powerful oxidizing agent. It is also a potent carcinogen and can cause severe irritation upon contact with skin, eyes, and respiratory tract.

It's important to note that the toxicity of a substance can depend on various factors, including the form in which it is encountered, the concentration, the duration of exposure, and the route of exposure (ingestion, inhalation, or dermal contact).

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Osmium tetroxide is highly volatile and penetrates skin readily, and is very toxic by inhalation, ingestion, and skin contact. Airborne low concentrations of osmium tetroxide vapor can cause lung congestion and skin or eye damage, and should therefore be used in a fume hood.read more >>