Most professional armies would have chemical units for the purpose of protecting their troops from an attack, and disposing of the hazardous material from such an attack.
My understanding of the Iraq army is that they followed Soviet Doctrine. Chemical units would be present in larger units in that case would it not?. I'm guessing (as I don't have reference present) Regiment and above.
Isn't it reasonable to suppose that this could be the case here?.
My understanding of these units is that they do not launch chemical attacks.
This is not to say that Iraq did not have units which were trained to launch chemical attacks through artillery, but, we should be careful to differentiate the missions.
I think proof of the intent to launch such an attack will be found with precursors and artillery shells designed for this purpose. Not necessarily in units trained to DETECT and decontaminate.
My .02