Some truthers suggest that because NIST does not test for explosives then this means that the NIST report is unscientific, and so nothing it contains should be believed. The same argument is made about the steel. I think there's plenty of science in the NIST reports (most of it really) that is independent of such tests. IN WTC7 in particular there was extensive analysis of the spread of fire, and the projected effects of fire on steel, and the way the building collapsed. No testing for explosives does not change the observations of the way the building collapsed, nor does it change the observations of how the first spread. NIST makes a very good case about how the building collapsed by fire. Characterizing one aspect of their investigation as "unscientific" does not alter the other aspect of the investigation. NIST Explains in a lot of detail why they do not think there were explosives, did not test for explosives, and other claims of evidence of explosives, and suggestions that they did not follow code, or they were not scientific: http://www.nist.gov/el/disasterstudies/wtc/faqs_wtc7.cfm In addition, tests of the dust actually HAVE been conducted, and no evidence of explosive residue was found beyond, as NIST explained, elements that you would expect to find anyway.