Trajectory of inhaled cadmium ultrafine particles in smokers

Abstract

Trajectory of inhaled cadmium ultrafine particles in smokers

Introduction: Tobacco smoking is a significant source of cadmium exposure among smokers. Most of inhaled heavy metals, including cadmium, are attached to ultrafine particles (UFP) surface. A low inhaled UFP content in exhaled breath condensate (EBC) reflects a high inflammatory status of airways. (Fireman Klein E. et al. Int J Chron Obstruct Pulmon Dis 2019). Increased respiratory epithelial permeability and translocation to the circulation is the proposed mechanism. UFP recovered from smokers' airways have high levels of cadmium compared to the airways of non-smokers. (Fireman Klein E. et al. Cigarette-related cadmium and environmental pollution exposure are reflected in airway ultrafine particle content. ERJ Open Res. 2020 Sep).

Methods: Urine was collected from 22 smokers subjects and 43 non-smokers. Samples were analyzed for UFP and cadmium content. UFP were measured in urine samples by means of the NanoSight LM20 system. A Niton XL3 X-ray fluorescence (XRF) spectrometer analyzer quantified heavy metal contents in the urine samples.

Results: Smokers had elevated UFP and cadmium content in urine compared to non-smokers (4.6 E8/ml and 20.6 ppm vs 3.4 E8/ml and 18.5 ppm, p=0.05 and p=0.05, respectively). Smokers had elevated levels of lead and rubidium compared to non-smokers (8.9 ppm and 27 ppm vs 7.8 ppm and 2 ppm, p=0.05 and p=0.04, respectively)

Conclusions: We suggest that the trajectory of cadmium-related UFP in smokers begins by its inhalation into the airways. The UFP induce inflammation and oxidative stress in the small airways, are subsequently translocated from the interstitium to the circulation, and are finally detected and secreted in urine