Visualizing and quantifying human internal black carbon load

Worldwide, outdoor air pollution is responsible for 4.2 million premature deaths per year. Both chronic and acute exposure to particulate matter air pollution is a risk factor for heart and lung diseases. One of the atmospheric pollutant particles is represented by soot or black carbon (BC) particles, which are produced during the incomplete combustion of fuels. To evaluate human BC exposure, a direct and label-free approach for detecting such particles in body fluids and tissues was still lacking. We present a novel technique to finally close the diagnostic gap. We report for the first time white-light generation by CBs under femtosecond pulsed near-infrared light illumination in aqueous environments and demonstrate the potential of this approach in biomedical and diagnostic context. In fact, it was shown that urinary carbon loading can serve as an exposure matrix to carbon-based air pollution, reflecting the passage of soot particles from circulation into urine. Furthermore, using this technique we reported the presence of BC particles in human placentae. This suggests that ambient particulates could be transported towards the fetus and represents a potential mechanisms explaining the health effects of prenatal air pollution from early life onwards. The novel method is straightforward, fast and flexible without the need of sample pretreatment. Moreover, the technique offers several other advantages such as inherent 3D sectioning and high imaging depths making it possible to screen at the cellular and tissue level. In conclusion, this novel diagnostic technique allows to quantify exposure at the personal level including different scenarios like occupational exposure, smog, forest fires, etc.. Additionally, this approach paves the way to unravel the complexity of soot-related health effects.