NYC-WTC_000232959

NYC 9/11 Public Portal Document

for both silicosis and lung cancer. Therefore these data cannot rule out the potential for long-term risk. However, the highest airborne level measured during this study is not necessarily representative of long-term exposure. In addition, the XRD analysis for quartz in air is semiquantitative (i.e., an estimated value). This adds additional uncertainty to the risk estimation. As presented in the discussion section of this report, it is expected that the ongoing cleaning of lower Manhattan and natural dispersion should reduce these materials over time, thus reducing long-term risk. Therefore cleaning should be continued and levels of respirable crystalline silica monitored, until the data demonstrate that long-term risk of adverse health effects is minimal.

6. Synthetic Vitreous Fibers

The term synthetic vitreous fibers (SVF) refers to several types of manufactured vitreous fibers: glass wool, mineral wool, and refractory ceramic fibers (RCF) (41,42). Because RCF was not found during this investigation, its health effects are not discussed. The types of SVF found in settled surface dust, glass wool and mineral wool, are primarily skin and upper respiratory tract irritants. Although some data do mdicate a potential for pulmonary effects, no adverse effects on the lung are expected from the levels measured in this investigation.

a. Irritant Effects

The primary short-term and acute health effects of SVF are skin, upper resphatoiy tract, and eye No long-term health effects are irritation (42). It is the physical shape and size of expected from the skin and eye the SVF fibers that cause irritation, generally irritation that may have occurred fibers more than 5 microns in diameter cause because of exposure to synthetic skin irritation (41,43,44). The affected area may vitreous fibers. itch and a rash may form. These symptoms subside as exposure is ended, as the fibers IVo adverse pulmonary health effects slowly work themselves out of the affected tissue. are expected from the levels of Upper respiratory tract irritation due to inhaled airborne synthetic vitreous fibers fibers has been reported when fiber concentrations measured in this investigation. were greater than 1 f/cc in air (41,42,45).

Generally this type of irritation has been observed in individuals who are manufacturing and installing SVF insulation materials. Although the settled surface dust results indicate SVF is present in many areas of lower Manhattan, total dust loading is not known. Because these irritant health effects would be due to the total amount of SVF contact exposure, dust loading as well as activity levels would influence whether a particular environment was irritating. Extremely low levels were detected in the air samples analyzed via SEM. In the PCM analysis, even if all of the fibers counted are assumed to be SVF, the detected maximum value of 0.003 f/cc is well below the documented level of irritation. These data indicate that SVF is present at elevated levels in settled surface dust and may be an irritant under certain conditions, or to sensitive individuals. No long-term health effects are

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