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 38 of56 µg/m 3 = microgram of mineral per cubic meter of air

total = all airborne particles (could Include particles >100 micrometers)

res PM4

3. Mica

Mica Is a group of water-insoluble silicate minerals (18). The mica detected In these dust and air samples of lower Manhattan was muscovite. Mica has been shown to cause pneumoconlosls In workers exposed to high levels during mining and processing operations (19,20). Although workers may have also been exposed to quartz In some of these studies, pneumoconlosls In workers with only mica exposures has been documented. (21,22)

Resplrable mica particles that deposit In the deep lung may be cleared slowly due to the relative Insolubility of the mineral. Over time, the presence of the mineral will Irritate the lung tissue, generate Immune response, and result In scarring or fibrosis (23,24). The magnitude of this response Is believed to be a function of both the dose and duration of exposure. The current worker standard set at 3,000 µg/m 3 Is a level at which mild

pneumoconlosis was seen In some workers only after extended exposure (18 years).

Mica and halite, although elevated In lower Manhattan relative to the comparison areas above 59th Street, are not likely to contribute to any adverse health effects.

The airborne levels of mica seen in lower Manhattan with an estimated maximum of 43 µg/m 3J in respirable dust are well below levels of mica that are associated with the development of pneumoconiosis in workers (25). Although disturbing settled surface dust might generate short-term exposures above the measured values, it is the cumulative exposure that is believed to predict health effects (23). Given the low airborne levels of mica seen in lower Manhattan and the low frequency of detection in both air and settled surface dust samples, no health effects are expected from mica exposure alone.

4. Halite

Halite is simply sodium chloride, or rock salt (18). This crystalline form of the salt will readily dissolve In the body and is not expected to have any adverse health effects. Although large changes In salinity can disrupt tissues, the trace amounts of halite and the low frequency of detection do not indicate any potential health concern.

5. Crystalline Silica (Quartz and Crlstoballte)

http://www.atsdr.cdc.gov/asbestos/lowermanhattan/ResSamp_Sep2002_Text.html 07/18/2003 NYC-WTC_ 000146698