VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

rv.c. Polychlorinated Biphenyls (PCBs)

PCBs are a group of synthetic organic chemicals potentially composed of 209 individual chlorinated biphenyl compounds (known as congeners). PCBs were manufactured as mixtures of individual compounds having 1 to 10 chlorine atoms on the molecule. Being relatively stable compounds, their high boiling points and resistance to breakdown by high temperatures made them useful in a broad array of industrial applications. Furthermore, as PCBs do not conduct electric current, they were useful for commercial purposes as insulating material and electrical dielectric fluid in transformers and capacitors.

In 1971, Monsanto Corporation, the major U.S. producer, voluntarily restricted the sales of PCBs to uses as dielectric fluids in “closed electrical systems.” This restriction was prompted by growing evidence of PCBs’ persistence in the environment, their tendency to bioaccumulate in animal tissues, and their toxic effects, namely as probable human carcinogens. Monsanto ceased PCB manufacture in mid-1977 and shipped the last inventory in October 1977 (Erickson, 1997). Regulations issued by EPA beginning in 1977, principally under the Toxic Substances Control Act (40 CFR 761), have strictly limited the production, import, use, and disposal of PCBs.

Because the WTC was built in the early 1970s, it can be surmised that PCBs may have been present or contained in transformers, capacitors, electrical insulating and cooling applications, fire-resistant coatings to building materials, and electrical fluorescent lighting fixtures. As a consequence of the collapse of the WTC towers, many of these materials were pulverized, ruptured, or burned, which caused PCBs to be released into the surrounding environment. Additionally, PCBs were likely entrained within the smoke plume that emanated from the debris piles at Ground Zero. The primary focus of this section is to evaluate the potential human health risks that may be associated with inhalation exposure to the variable air concentrations of PCBs measured in lower Manhattan in the aftermath of the disaster.

IV.C.1. Air Monitoring for PCBs PCBs were monitored at 12 different sites around Ground Zero and in other areas of lower Manhattan. Several hundred ambient air samples were collected between September 16, 2001, and April 24,2002. One-day samples were taken using a high-volume polyurethane foam (PUF) and glass fiber filter (GFF) sampler. The GFF is used to collect and retain PCB- contaminated particles that may be present in the air, whereas the PUF material is used to capture any gaseous form of PCBs. In this monitoring program, only the sum of the PCB congeners present in air was quantified. Figure 21 displays the locations of the PCB air monitoring stations in lower Manhattan.

The primary source of PCB monitoring data used in this analysis was the publicly accessible information posted on EPA’s WTC web site (http://www.epa.gov/wtc). This information is current through April 24, 2002. Table 3 presents a summary of the ambient air sampling results for PCBs in and near the WTC disaster site.

To put these measurements into perspective, background levels of total PCBs in air at urban locations in the U.S. are typically in the range of 1 to 8 ng/m’ (ATSDR, 2000a). Slightly elevated air concentrations were found up to 1 month after September 11 only at the Ground

DRAFT-DO NOT QUOTE OR CITE 66 October 2002

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