Abstract
The air in Santiago, Chile, is among the most highly polluted in the world. Due to the high levels of pollutants and the high incidence of respiratory diseases, especially in the most susceptible groups, Santiago has been declared a saturated zone for PM10, O3, and CO. The levels of 16 polycyclic aromatic hydrocarbons (PAHs) were determined by HPLC in organic extracts from total suspended particles (OETSP) and respirable particles (OERP). Respirable particulate matter (fine and coarse) contain high levels of PAHs including six classified by IARC as carcinogenic, and represented at least 45 % of total PAH concentrations. A seasonal effect was observed with higher values in months with lower temperatures. Although a substantial decrease in PAH levels from OETSP and OERP has been observed in recent years, the levels of carcinogenic PAHs are still higher than those reported in cities in the USA, Australia and Europe. OETSP and OERP were highly mutagenic and contained direct and indirect mutagens which produced both frameshift and base substitution mutations in Salmonella thyphimurium. OETSP were also highly mutagenic at the tk locus in hlAlv2 human lymphoblasts in culture and their mutagenic potencies were 400 fold higher than those reported for PM10 in Los Angeles, USA. In vitro incubation of OETSP and OERP with calf thymus DNA allowed the identification of five nitro-PAH-DNA adducts, suggesting a relevant contribution of nitroarenes to particle toxicity. In spite of the important decrease in PAHs in the period 1991-1996, direct mutagenic responses have not changed significantly, suggesting that the levels of direct mutagenic pollutants (e. g nitroarenes) have not decreased substantially during recent years. Aditionally, indoor air pollution was investigated in an area of extreme poverty in Santiago; high levels of PM10, CO and PAHs were found which might explain the high incidence of respiratory diseases in this subpopulation. These results suggest that Santiago's inhabitants are exposed to pollutants adsorbed onto respirable particles that are highly mutagenic, thus representing a risk for human health.