NYC-WTC_000199886

NYC 9/11 Public Portal Document

Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons

None of the ten surface samples contained PCBs at concentrations above the laboratory method reporting level (2 ug). None of the ten surface samples contained polycyclic aromatic hydrocarbons above the laboratory method reporting limit (5 ug).

Dioxin/Dibenzofurans

Trace levels of dioxins and dibenzofurans were detected in nine of the ten surface wipe samples collected, as expected. Only the sample collected from the gymnasium floor did not contain any measurable dioxin. TCDD equivalent concentrations were reported at highest concentrations in three wipe samples collected from windowsills (0.017 to 0.041 ng/m^) and lower in samples collected from tabletops and bookcases (0.00018 to 0.00074 ng/m^). There are no established standards for dioxins/dibenzofurans on surfaces. The National Research Council (1988) has a published a recommended surface criterion for dioxins of 25 ng/m^ for an office building setting, and cites recommended concentrations in several states ranging from 1 to 25 ng/m^. ENVIRON developed a preliminary screening level of 0.055 ng/m^ using a USEPA risk-based approach, reasonable exposure assumptions for a school setting, and very protective risk targets (10'^). All of the reported TCDD equivalent concentrations were less than the preliminary screening level, and well below the recommended criteria cited by the National Research Council.

Metals

Metals were detected in all samples, as expected. Common metals, such as iron, copper, manganese, and zinc were detected in all 10 samples. Trace metals, such as chromium, cadmium, and nickel, were detected in four or less of the samples. Only lead has regulatory levels for surface dust (lead was discussed above). ENVIRON developed preliminary screening levels for the analyzed metals utilizing a USEPA risk-based approach, with reasonable exposure assumptions for a school setting, and very protective risk targets (10'^). All of the detected metal concentrations were below the preliminary screening levels.

Mold Assessment

Because there was some minor flooding in the basement of the school in the few days immediately after September 11, an assessment was performed to determine if there were any issues related to mold growth or fungal spores in the school. An inspection was performed of the basement by ATC Associates on October 31 which found no evidence of microbial growth or mold growth evident. ENVIRON performed a follow-up inspection and made the same observations. To confirm those observations, sampling for fungal spore counts was performed inside and outside the school on December 18,2001. , That sampling found that spore counts inside the school were lower than outside the v' school, indicating no evidence of amplified fungal growth in the school.

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NYC-WTC_000199894