Toxic evaluation of organic extracts from airborne particulate matter in Puerto Rico

In recent years, several hypotheses have emerged to explain the toxicologic activity of particulate matter. Organic compounds, ultrafine particles, bi ologic components, and transition metals are some of the constituents that reportedly exert some type of adverse effect on human health. A considerabl e fraction of the urban particulate matter consists of carbon compounds, wh ich originate mostly from anthropogenic sources. The toxicity of organic fr actions from particulate matter have been mainly evaluated by considering t heir mutagenic activity. This research expands on the toxicologic profile o f organic compounds adsorbed to particulate matter, specifically in Puerto Rico, by using the cytotoxic neutral red bioassay (NRB). The NRB uses norma l human epidermal keratinocytes or other types of cells to measure the effe ct on cell viability when exposed to organic compounds associated to the pa rticles in the air. We validated the NRB for particulate matter by using a standard reference material (SRM 1649). We used the NRB to determine toxico logic differences of extracts between an urban industrialized site with ant hropogenic activity versus a coastal region with less human activity. The c ytotoxicity associated with organic compounds in particulate matter collect ed at the urban industrialized site was detected in both the particulate ma tter less than or equal to 10 mu m in aerodynamic diameter (PM10) and parti culate matter less than or equal to 100 mu m in aerodynamic diameter (PM100 ). Greater toxic effects were observed in PM10 extracts than in PM100 extra cts, but PM10 toxic effects were not significantly different from those in PM100. The extracts from the industrialized site were more cytotoxic than t he extracts from coastal reference site, although in the summer, extracts f rom both sites were significantly cytotoxic to normal human epidermal kerat inocytes. In addition, the nonpolar extracts of both PM10 and PM100 exerted the greatest cytotoxicity, followed by the polar, and, finally, the modera tely polar extract. This study demonstrates that extracts from the Guaynabo industrialized site were more toxic than similar extracts obtained from a reference coastal site in Fajardo, Puerto Rico.