Study of pH and Cellular Response in Pulmonary Fibroblasts After Exposure to Market Street World Trade Center Particulate Matter

Chronic health conditions have been noted among first responders and residents exposed to the dust generated from the World Trade Center (WTC) collapse on September 11, 2001. This study sought to isolate a single factor thought to play a substantial role in the decreased lung function of World Trade Center (WTC) workers and victims. Human pulmonary fibroblasts were exposed to 0 (control), 2.5, 25, 250 mg mL^-1 WTC dust at 5% CO₂ and 10% CO₂ to test the hypothesis that cellular toxicity is attributed to the high pH (9.3) of the WTC dust. A decrease in viability, increase in toxicity, as well as increased apoptotic activity with increased WTC dust exposure at 5% CO₂ were observed 24 h post exposure. Exposure of cells under 10% CO₂, which reduced the high pH of the media, significantly increased viability, as well as decreased toxicity and apoptotic activity. Our results show that cellular toxicity can be mitigated by reducing the pH of the exposure condition and that high alkalinity is one of the most important factors in producing cellular toxicity in vitro.