As the location and time of film footage cannot be ascertained, it is impossible to say whether the civilians were exposed to a mixture of toxic agents or different agents were released over different suburbs, Zanders wrote. Images of dead birds, cats and dogs tend to support impressions of a large volume of a rather fast-acting agent having been released in some locations.
Dan Kaszeta, a chemical and biological warfare expert who runs the consulting firm Strongpoint Security, emphasized that without access to the scene, researchers will have a very difficult time determining exactly what happened.
One issue is that you cant really test for sarin gas, you test for chemicals that are released as it decomposes, he said, adding that hospitals in Lebanon or Syria probably dont have the state-of-the-art chemical laboratories to carry out the tests.
Theres a wide range of reported casualties, which only adds to the confusion and fuels the accusations of the pro-Assad camp that the opposition is exaggerating the numbers in hopes of inviting foreign military intervention that could help collapse the Syrian regime.
The Syrian Observatory for Human Rights, a pro-rebel monitoring group based in London, said on its Facebook page that it has documented the deaths of 136 people, including dozens of women and children, in the Ghouta attacks. A representative of the group said in an online interview that researchers were combing through hundreds of other names of purported victims and expects the final casualty figures to increase.
State Department officials say theyve received reports that between 1,000 and 1,800 people were killed, figures that have been put forth by opposition figures.
McClatchy special correspondent Prothero contributed from Lebanon; James Rosen contributed from Washington; Matthew Schofield contributed from Berlin.