Here is an article, that perhaps you didn't see, but it would be a good idea to read.
Report: Palestinians able to carry out chemical attack
Palestinian terror organizations have the ability to carry out a chemical attack in Israel, but have refrained from doing so to date due to the repercussions of such an attack, a senior Israeli security official said this week.
"It is not a problem for terror organizations to attain chemical materials, and they are aware of the advantages of such an attack, but on the other hand [they know] it would be considered breaking all the rules of the game," the official said at a briefing.
He noted that such an attack could kill hundreds or thousands of people, as opposed to the dozen or so people killed in conventional Palestinian suicide bombings.
Chemical materials are readily available at scores of factories across the country, he said, including at the seemingly innocuous Tnuva milk factory in Jerusalem.