NYC Law Department letter regarding EPA draft report excerpts, July

NYC 9/11 Public Portal Document

Final Technical Report of the Public Health Investigation Page 26of56 distribution of the minerals.

Calcite (calcium carbonate) and portlandlte (calcium hydroxide) are also components of concrete. They occurred with similar frequency In the dust samples and were often co-located with the quartz. calcite ranged from an estimated 0.8%J to 19%J in outdoor areas, and from 0.02%J to 21 %J in Indoor areas. Portlandlte ranged from an estimated 0.07%J to 6%J In outdoor areas and from 0.04%J to 8%J In indoor areas. In contrast, the maximum levels found In indoor comparison areas above 59th Street were 0.9%J calcite and 0.08%J portlandlte. Figures 13 and 15 show the locations where the estimated calcite and portlandlte content In settled surface dust was higher than to that estimated in dust samples from the comparison areas above 59th Street. For calcite, 13 residence and 9 common area samples had estimated levels higher than those found in the comparison areas above 59th Street. Similarly for portlandlte, 17 residence and 9 common area samples were estimated as higher than values in comparison areas above 59th Street. So although these materials are found In urban areas, perhaps due to erosion of concrete, building construction and maintenance, the estimated percentages of calcite and portlandite were larger In some areas of lower Manhattan relative to the comparison areas above 59th Street (Figures 13 and 15.)

Gypsum (hydrated calcium sulfate) Is a major component of dry wall. Gypsum was found in 11of14 outdoor settled dust samples at levels estimated as 0.03%J to 27%J. Indoor levels of gypsum ranged from an estimated 0.07%J to 20%J in 23 of 26 common areas and from 0.05%J to 30%J In 45 of 57 residences. These estimated percentages are higher than the estimated maximum of 4%J seen In the comparison areas above 59th Street. Figure 14 shows the locations where the estimated gypsum content In settled surface dust was higher than or similar to the levels in the dust samples from the comparison areas above 59th Street. Nine residence and six common area samples had estimated levels higher than those found In the comparison areas above 59th Street. Gypsum was elevated In settled Indoor dust In some areas of lower Manhattan relative to the comparison areas above 59th Street (Figure 14).

The data can also be evaluated In a nonquantitative manner by just Inspecting the frequency of detects of mineral In dust for lower Manhattan and the comparison areas. As shown In Table 7, the pattern of prevalence for the minerals appears to be similar In both study areas. In other words, the minerals were detected In both locations with about the same frequency. The data Imply that building materials were the source for both areas. This source was likely building materials; however, the magnitude of the Impact was greater in areas closer to the World Trade Center.

3. Alkalinity of Settled Surface Dust

Several of the minerals detected In the settled surface dust samples, such as portlandlte, can make the dust more alkaline, or raise the pH. Originally, the pH of all of the settled surface dust samples was to be determined. However, enough dust for this analysis was only available at two locations. Both dust samples

http://www.atsdr.cdc.gov/asbestos/lowermanhattan/ResSamp_ Sep2002_Text.html 07/18/2003 NYC-WTC_000146686