The standard application rate in pecan orchards, for example, is 20 lb/acre (employing a granular powder that was 15% active ingredient). I used as little as 3 lb/acre, applied tree-by-tree, and still got effective control of pecan aphids.
Temik can be inhaled, ingested, enter via a wound or be absorbed into the skin. Small dosages can be fatal, microscopic doses can do damage. Accordingly, simply being around this stuff is dangerous. It was the only material we ever worked with on the farm that I was actually afraid of.
Temik is expensive, as agricultural chemicals go, but dirt cheap as far as chemical warfare would be concerned. Simply scattering it on the ground around abandoned installations, or spraying it into rooms, would be an effective "scorched earth" tactic. In a desert climate, it would remain active until solubalized and washed away by a rain (in which case, don't drink the well water).
I'm not suggesting that the Iraqis may have used Temik, per se, in the Gulf War. But they could very well have employed a relatively common (and low cost) ag chemical for this purpose.
And they could have "complemented" the anthrax in a similar fashion -- though I don't know if they could've gotten the same aerosol effect on such a chemical as they did on the spores.