"The news reported today the British Osmium Tetraoxide plot was masterminded from Pakistan."
"Masterminded" might be a bit of an overstatement. In fact, it is way overstated! Osmium Tetroxide, OsO4, is probably one of the most impractical compounds that could ever be selected for use as a chemical weapon component of a terrorist bomb.
First, a mere 100 grams of OsO4 would cost between $5,000 and $6,000. Osmium is roughly about 10 times more valuable than gold!
Second, the vapor concentration needed to cause death, in any reasonable time frame, would be too high to make it a practical mass weapon. The safety levels specified in "Material Safety Data Sheets" are just that: safety data and don't reflect the reality of the compound when used as a weapon to cause death.
Third, the blindness is usually recovered spontaneously and completely within 24 hours.
Fourth, virtually its only commercial use is in the field of scanning electron microscopy. This makes it much easier to track down the perps, as the material was likely stolen, not purchased. And given the very high price and low usage rate of OsO4, stocks on hand will be very small.
So what clues can be gleaned from any intended use of OsO4 by terrorists? Look for someone with very little common sense (a polite way of saying "stupid as a box of rocks") and who works around scanning electron microscopes.
--Boot Hill