NYC-WTC_000199812

NYC 9/11 Public Portal Document

4.2.2 Surface Dust and Bulk Samples

The samples were prepared and analyzed to determine the presence of mercury and the other 22 metals as described in Section 4.2.1.

4.3 Results of Surface Dust and Bulk Samples

The analyses of 23 metals present in the dust deposited in the “high” and “low” exposure apartment buildings are presented in Tables 4 and 5. These tables present surface wipe and bulk dust sample analyses. The aoBcentnrtiens of metals with thc highcst potential chronic toxicity ^uch as arsenic, beQ<llium, cadmium, chromium, lead, mercury, and nickel) are relatively foWwsiMaiaak'fieesajji Regarding lead, a dust-lead hazard is defined as a surface in a residential dwelling or child-occupied facility that contains a mass-per-area concentration of lead equal to or exceeding 40 /zg/ft^ on floors or 250 /xg/ft^ on interior window sills based on wipe samples (Federal Register, Vol. 66, No. 4, January 5, 2001). By comparison, apaftments ranged from 141@ 30 Calcium represented approximately 9 to 19 percent (9.1-190,000 jj-g/g) of the metals present in the dust. Mineral wool in the Trade Center Towers contained a large percentage of calcium. Mineral wool made up approximately 60 percent of the fireproofing. Calcium oxide (lime) is a primary component of cement, calcium sulfate (gypsum) is the primary component of wallboard (drywall), and calcium is a primary component of mineral wool (fireproofing). Because calcium oxide is alkaline and reacts with moisture to form calcium hydroxide, exposure to the dust can irritate the eyes, mucous membranes, and/or skin.

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NYC-WTC_000199830