EPA interim final report on WTC background study, April 2003

NYC 9/11 Public Portal Document

Chromium

Chromium is a naturally occurring element commonly used in metal alloys and plumbing coatings in high rise buildings such as the WTC. Chromium and its compounds can be found in air as very fine dust particles that eventually settle over land, and can cause cancer and other health problems if inhaled at high concentrations. To date, in over 300 air samples, levels of chromium measured in ambient air around the WTC work zone have all been below EPA’s screening level of 0.6 ug/m’ in the ambient air (see Appendix B). Measurements in settled dust [EPA 2002c, Lioy 2002] have been below EPA Removal Action Guidelines [EPA, 1997]. Because of these low values, chromium is not being considered a hazard at the WTC site. Therefore, chromium will not be monitored in any indoor environment testing.

Cadmium and Manganese

Cadmium and manganese, both hazardous air pollutants, were detected in some ambient air samples taken at the WTC site. However, in over 300 samples, cadmium was found in only two samples at levels over EPA’s screening level of 0.2 ug/m’ in the ambient air (see Appendix B). In over 300 samples, manganese was found in only four samples at levels above EPA’s screening value of 0.5 ug/m’ in the ambient air (see Appendix B). Because of the low ambient concentrations of these two metals, they will not be monitored in any indoor environment testing.

Mercury

In late December 2001, it was reported that four New York City Port Authority police officers were tested with elevated levels of mercury in their blood. This raised concerns over the air quality at the WTC area. The officers were retested under medical surveillance to determine whether the source of mercury was the air over the WTC. The retesting found that the levels of mercury in the officers’ blood and urine were below levels of concern established by NYCDOH and the American Conference of Governmental Industrial Hygienists. The cause of the first elevated mercury levels is not known, but may be fi-om something that the officers had eaten the day before the blood tests were done, and not WTC air. In fact, Rottner [2002] has reported only one mercury air sample above detection limits to date in the WTC area.

In addition, data from a U.S. Geological Survey leachability study [USGS, 2001] performed on both indoor and outdoor WTC dust samples found mercury in leachate samples only at trace levels (up to 18 parts per trillion [ppt] for outdoor dust and 130 ppt in indoor dust). Because only trace levels of mercury appear to be present in indoor dust samples, the probability that harmful levels could ever be released to the air is very low. Therefore, mercury will not be monitored in any further indoor environment testing.

Particulate Matter

Particulate Matter (as fine dust and smoke) in the 10 micron and smaller size range is inhalable

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