PAHs and mutagenicity of inhalable and respirable diesel particulate matter in Santiago, Chile

Delayed human effects such as cancer could be a consequence of chronic exposure, over long periods of time, to inhalable (PM₁₀) and respirable (PM_2.5) particles containing environmental carcinogen mixtures. Air pollution in Santiago, Chile, is a major public health problem due to the high levels of regulated pollutants such as PM₁₀, CO, and ozone. In this work, we studied the levels of polycyclic aromatic hydrocarbons (PAHs) onto PM₁₀ and PM_2.5 collected in diesel revision plants, in an urban area with a high flow of buses and trucks and in a rural area not exposed to diesel emissions. The PM₁₀ average levels in diesel emission plants were higher than the Chilean PM₁₀ standard and higher than those found in the urban and rural areas. In the urban area the PM₁₀ average levels were lower than the Chilean PM₁₀ standard, although some 24 h levels surpassed the levels established to decree preemergency or emergency and in some cases were higher than the levels reported by all the official monitoring stations. The levels of total PAHs onto PM₁₀ were higher in the diesel plants than in the urban area and rural area, but the levels of six carcinogenic PAHs were similar in the diesel plants to those found in the urban area. Organic extracts from PM₁₀ collected in diesel plants in Salmonella typhimurium TA98 in the presence and in the absence of an S9 activation system were significantly higher than in the urban area and rural area. Mutagenic activity with and without S9 in diesel plants and the urban area showed that indirect (PAHs) and direct (nitro-PAHs) mutagenic compounds are present in organic extracts from PM₁₀. In conclusion, these results showed that in Santiago diesel emission particles were highly mutagenic and contain carcinogenic PAHs. This might represent a risk for long-term respiratory effects in Santiago's inhabitants.