VOC sampling locations table for Ground Zero area, Jan 2002

NYC 9/11 Public Portal Document

IV.b. Metals

rv.b.l. Lead Lead, a silver-grayish soft metal with a relatively low melting point, was still widely used in the 1960s and 1970s (when the WTC was built) in paint and for soldering indoor plumbing joints and electrical wiring systems. It was also used for soldering of computer circuit boards and wiring in a variety of electrical appliances. These uses make it likely that lead would be among the toxic substances of concern at the WTC site. Lead could have been emitted as a combustion product of the ensuing fires or could have been present in reentrained particles stirred up into the air in the course of recovery activities and transport of debris away fi-om the WTC site.

The potential public health concern due to lead exposure most relevant for consideration in relation to the WTC situation is lead intoxication associated with prolonged low-level lead exposures. As discussed in EPA (1986b), such exposure can result in subtle, often subclinical, health effects such as altered calcium metabolism and bone formation/loss, slowed physical growth, and slowed nervous system development of the fetus. Effects on the fetus may be due to exposure of the mother during pregnancy, therefore, women of childbearing age have been identified as an important susceptible population. Other effects of lead intoxication may be slower postnatal growth and neurobehavorial development, IQ decrements and learning deficits, and other neuropsychological effects among young infants and children (another susceptible group).

In 1978, the EPA NAAQS for lead was set at 1.5 gg/m’ (90-day average). This level was set to reduce the risk of occurrence of lead intoxication impacts associated with prolonged low- level exposures of susceptible groups. With the EPA phase-down of lead as an additive in gasoline during the past several decades and the current widespread use of unleaded gasoline in the U.S., ambient air lead concentrations have decreased dramatically. Before the start of the phase-down of lead in gasoline in the late 1970s, air lead levels as high as 2.0 pg/m’ or more were often detected in U.S. urban areas such as NYC. Currently, 24-hour ambient air lead levels below 0.5 pg/m’ are typical of NYC and other U.S. urban areas. NYSDEC Annual Air Quality Reports, for example, indicate (a) arithmetic mean annual-average 24-hour airborne lead levels during 1994 - 1998 of 0.04 to 0.08 pg/m’ for a Manhattan (Madison Ave.) curbside sampling site (maximum daily value = 0.34 pg/m’) and (b) arithmetic mean annual-average values ranging fi-om 0.02 to 0.09 pg/m’ for three Brooklyn/Staten Island sites (maximum daily value = 0.63 pg/m’) during 1992 - 1997.

Before the start of gasoline lead phase-out, lead concentrations in outdoor dust were reported (in studies assessed in EPA, 1986b) to range from 280 to 1500 pg/g (ppm) in residential areas of NYC and Philadelphia and from 900 to 13,000 pg/g in street dust or near heavily traveled roadways in several northern U.S. urban areas (NYC; Philadelphia; Washington, DC; Chicago; Detroit). Despite significant decreases in air lead concentrations, soil and street dust lead concentrations in excess of 500 - 1000 pg/g were still observed into the early 1990s in U.S. urban areas (e.g., Boston, Baltimore, and Cincinnati, as described in EPA, 1996). This may reflect, in part, the residuum from earlier gasoline lead deposition from air or more current contamination from deterioration of lead-based paint from residential or other structures or from

DRAFT-DO NOT QUOTE OR CITE 60 October 2002

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