Time-course detoxification of environmental metallic nanoparticles in human lung cells (A549)

Atmospheric particulate material (PM10), collected near to a metallurgical industrial area, caused internalisation of metallic nanoparticles. This is the first study of the bioavailability and detoxification pathway of metallic nanoparticles (NP) internalised into lung cells. Adenocarcinoma human alveolar epithelial lung cells (A549) were exposed to PM₁₀ arising from a polluted area affected by smelting activity in Brazil (Vitória, ES). A time-course ultrastructural analysis (0, 3, 6, 9, 12 and 24h) was used to verify the internalisation process and its subsequent detoxification. The metal bioaccumulation, biochemical changes and cytotoxicity analyses were evaluated in lung cells after 24 h exposure to 0, 1, 5, 10, 20 and 40 μg PM10 mL^-1. Time-course ultrastructural analysis showed that NP were internalised in both cytoplasm and nucleus after 1h exposure. Vesicles around internalised NP started forming after 3h; detoxification vesicles increased accumulating more NP between 6 and 12h exposure. Exocytosis was observed after 24h exposure. Five out of 28 analyzed metals (Al, Ti, Y, Fe and Ce) were bioaccumulated in the exposed cells. The emerging contaminants Ce, Y and Ti were mainly responsible for cytotoxicity effects. To our knowledge, this is the first record of the sequence of internalisation-toxicity, followed by physiological and biochemical responses, in lung cells exposed to atmospheric PM₁₀ from a metallurgical area. This indicates the need for specific regulation of atmospheric PM from the smelting industry worldwide, considering the presence and toxic levels of emerging metallic contaminants (EMCs).