NYC-WTC_000199812

NYC 9/11 Public Portal Document

(HRGC/HRMS) in accordance with EPA SW-846 Method 8290. The samples for PCBs as Aroclors (PCB-1016, PCB-1221, PCB-1232, PCB-1242, PCB-1248, PCB-1254, and PCB- 1260) were prepared and analyzed using gas chromatography with electron capture detection in accordance with EPA SW-846 Method 8082.

3.2.2 Surface and Bulk Dust

The samples were prepared and analyzed to determine the presence of PCDDs, PCDFs, and PCBs as described in Section 3.2.1.

3.3 Results

3.3.1 Surface Wipe

Table 2 presents concentrations of MS©«ff6W^expressed as 2,3,7,8- Tetrachlorobenzo-p-dioxin Equivalents') and,|#BB*The concentrations of 2,3,7,8-TCDD Equivalents ranged from 0.0012 to 0.088 ng/m\ By comparison, tlw’www numerically lowerthaftthe backgroundconcentrations (0^05^129 ng/m“) measured m* conunercial office buildings in thc United States^Kominsky andKwoka, 1989). The concentrations are also significantly less than the guideline (25 ng/m^ 2,3,7,8-TCDD Equivalents) recommended by the Nati©aal Ac»demy of Seieac&s, Subcommittee on Ehoxift (NAS 1988). /2g/m^) and are thus within comparative background levels (Kominsky et. al, 1989). The PCDDs and PCDFs were likely produced during the combustion of PCB-containing materials and chlorinated compounds such as PVC plastics. Historically, PCBs were used in dielectric fluids in electrical transformers and capacitors (e.g., fluorescent light ballasts and

1 The potential toxicity of mixtures of PCDDs and PCDFs in environmental samples is estimated by converting the respective concentrations of PCDDs and PCDFs to 2,3,7,8-tetrachlorodibenzo- p-dioxin (2,3,7,8-TCDD Equivalents) (EPA 1989). This mathematical conversion represents the estimated amount of 2,3,7,8-tetrachlorodibenzo-p-dioxin (i.e., the 2,3,7,8-TCDD isomer) that would have to be present to exhibit the same toxicity as the measured quantities of each of the various PCDDs and PCDFs that are present in a sample.

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CITY_21MC100_006730096

NYC-WTC_000199826