VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

High-level exposures to toluene (above 100 ppm) may affect the nervous system and kidneys. Headaches, confusion, and sleepiness are also seen after high-level exposures. A short­ term exposure study (4 days) in human subjects showed eye and nose irritation and neurological effects at 100 ppm; these effects were not seen at 40 ppm. The EPA-STSC provisional subchronic RfC for toluene is adopted directly from the EPA RfC for a lifetime exposure. The EPA-STSC confidence in this value is medium. This value is derived from a study where workers were exposed to 88 ppm of toluene for 6 years. In this study, adverse neurological effects were seen in the workers (EPA, 1999b).

A total of 335 toluene monitoring results were evaluated at sites surrounding Ground Zero. A summary of the available screening benchmarks and exceedences is shown in Table 14. The available benchmarks that were exceeded were the ATSDR acute MRL of 1 ppm and the EPA- STSC provisional subchronic RfC of 0.25 ppm. At Greenwich and Liberty, measurements taken on September 28 were collected in ground-level grab samples; on October 1, the sample was taken in a ground-level plume. Measurements taken at this site on September 16 through September 27 and on Oct 2 and 3 were all at levels below 0.02 ppm. From these data, it appears that exceedences did not last more than 4 days. At Liberty and Trinity, the September 26 sample was collected in a ground level plume. Four samples obtained between September 16 and September 23 and a breathing zone sample taken October 26 were all below 0.05 ppm.

The 24-hour toluene samples were three orders of magnitude (1000 times) lower than these grab sample exceedences. Similar to ethylbenzene, 1,3-butadiene, and acetone, this difference in toluene concentrations between the grab sample exceedences and the 24-hour samples demonstrates the difference between grab samples taken within a plume and the long-term average concentration of the VOC.

Findings from VOC monitoring: As discussed above, most of the samples that showed exceedences were short duration grab samples that were taken in a plume or at ground level, not in the breathing zone. In fact, the exceedences for benzene, ethylbenzene, chloromethane and toluene measured at Liberty and Trinity on September 26, all came from the same collected grab sample which was taken in a plume. Similarly, all the exceedences measured at Greenwich and Liberty for acetone, 1,3-butadiene, benzene, chloromethane and toluene, came from the same 3 collected grab samples. Because these are 4-minute grab samples, it is not known how long the plume lasted - from minutes to hours to days. These exceedences all occurred in late September and early October; available grab sample data before and after these exceedences are all lower in value. In addition to being grab samples, all exceedences occurred within restricted zones or just on the border of the restricted zones. Finally, all 24-hour samples of four of the VOCs - ethylbenzene, 1,3-butadiene, acetone, and toluene - were lower than the grab samples, by about a factor of 1000. On the basis of the available monitoring data, it is concluded that the exceedences of the screening benchmarks in the restricted zone did not represent a public health risk to persons living or working at sites surrounding Ground Zero for at least these four VOCs.

The data for benzene was not as definitive. When compared with the other VOCs, the 24- hour benzene samples were measured at levels that were closer in magnitude to the grab sample exceedences, within a factor of 10. This would suggest that the grab sample concentrations were

DRAFT-DO NOT QUOTE OR CITE 109 October 2002

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