VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

Zero site, WTC Building 5 SW. The highest one-day PCB air measurement of 153 ng/m’ occurred on October 2, 2001. This level is approximately three-fold higher than the next two PCB levels observed at WTC Building 5 on September 16 and October 4: 55.9 and 58.6 ng/m\ respectively. By November 2, PCB levels at this site had further decreased to 18 ng/m\ Measurements from November 6, 2001 to April 24, 2002 showed that total PCB levels in air decreased to below the limits of detection. Barclay and West Broadway registered the next highest one-day PCB air concentration at 77 ng/m’ on October 4. This monitor bordered a restricted zone, but could represent a concentration in an area just above the comer of Barclay and West Broadway that was unrestricted after September 19. This October 4 measurement was about nine times greater than the measurement taken October 2 at this site (8.3 ng/m^), and approximately ten times higher than typical urban backgroimd air. By November 2, PCB air levels had decreased to 9.7 ng/m\ Following November 2, total PCB was not detected at Barclay and West Broadway until Febmary 19, 2002, at which time a concentration of approximately 3 ng PCB/m’ was detected. From February 24, 2002, through April 24, 2002, PCB levels dropped below the limit of detection. Because the limits of detection were within the range of typical urban air measurements, it can be concluded that PCBs had dropped to and remained within this range of typical urban air concentrations after November 8.

To summarize, elevations above the typical background range of 1 - 8 ng/m^ were only seen in the initial month after 9/11, and only within Ground Zero and the border sampling location of Barclay and West Broadway. All monitoring sites to the west of Ground Zero showed no elevation above backgroimd PCB concentrations at any time in the month following the disaster. By November 8, PCB levels in air were within the range of expected urban background air at all monitoring locations, including Ground Zero.

IV.C.3. Potential Human Health Consequences of Exposure to PCBs in Air Different approaches are used here to assess potential health effects of exposure to PCBs at or near the WTC site. First, EPA’s procedure for estimating cancer risk is used. Then, comparison of air concentrations to benchmarks published by ATSDR, NIOSH, and OSHA are conducted.

EPA currently classifies PCBs as B2 carcinogens; a probable human carcinogen (IRIS, 2002). The basis for this classification stems largely from long-term animal studies supplemented with human studies. A 1996 study found liver tumors in female rats exposed to Aroclorsl260, 1254, 1242, and 1016, and in male rats exposed to 1260. These mixtures contain overlapping groups of congeners that, together, span the range of congeners most often found in environmental mixtures. Earlier studies found high, statistically significant incidences of liver tumors in rats ingesting Aroclor 1260 or Clophen A 60 (Kimbrough et al., 1975; Norback and Weltman, 1985; Schaeffer et al., 1984). Mechanistic studies are beginning to identify several congeners that have dioxin-like activity and may promote tumors by different modes of action.

PCBs are absorbed through ingestion, inhalation, and dermal exposure, after which they are transported similarly through the circulatory system. This pattern provides a reasonable basis for expecting similar internal effects from different routes of environmental exposure. Information on relative absorption rates suggests that differences in toxicity across exposure routes are small. The human studies are being updated; currently available evidence is

DRAFT-DO NOT QUOTE OR CITE 67 October 2002

NYC-WTC_000149011