Abstract

The exposures of the World Trade Center (WTC) dust of the September 11, 2001 tragedy are linked to increased respiratory problems and emergence of World Trade Center Cough. Zinc (Zn) and Lead (Pb) are among the many heavy metals found in WTC dust. Synergistic effects among several chemicals might be contributing to respiratory illness. The individual toxicity, and combination treatments of Pb and Zn at a particular ratio of concentration (1:10) typical to Market Streets were carried out on MRC-5 human lung cells. Cells were treated as both physiologically stressed (2.5% Fetal bovine serum, {FBS}) and unstressed (10% FBS) condition in vitro. Triplex assays indicated that Pb and Zn do show antagonistic effects with each other. The combination treatments of both Pb and Zn reduced high individual toxicity of either alone, in both stressed and unstressed cells. In summary, Pb, which is known to be highly damaging to human lung cells is modified by the presence of Zn. It can be possible that Zn is a reward in disguise to WTC victims. Without unusual levels of Zn, Pb might be much more damaging to those exposed to WTC dust.

Key words: World Trade Center, toxicity, synergistic, antagonistic, stressed cell, unstressed cell, heavy metals.