Risk assessment of trace elements in airborne particulate matter deposited on air filters using solid sampling ETV-ICPOES to measure total concentrations and leaching with simulated saliva, gastric juice and lung fluid to estimate bio-accessibility

Potentially toxic elements (PTEs) in airborne particulate matter (APM) can cause adverse effects on human health, especially in urban and (current and former) industrial areas. The severity of health effects depends on the availability of the PTEs for absorption into the human body. The bio-accessible fraction of PTEs in APM, i.e. released in the gastrointestinal tract and lungs, was estimated in the present study. Polytetrafluoroethylene (PTFE) filters containing previously collected airborne particulate matter were directly analysed by electrothermal vaporisation into inductively coupled plasma optical emission spectrometry (ETV-ICPOES) to obtain the total concentrations of several trace elements (Sb, As, Cd, Cr, Cu, Mn, Ni, Pb, Sr, V and Zn). The results were cross-validated using inductively coupled plasma mass spectrometry (ICPMS) analysis of acid-digested samples. Subsequently, the bio-accessibility of the investigated elements was estimated by leaching the filters with simulated saliva (for 10 min, pH 6.5) and gastric juice (for 2 h, pH < 1). Separate aliquots were also leached with lung fluid (pH 7.4) for 1 h to 56 h. Two leaching groups were identified with saliva: As, Cr, Cu and Sb (2.5% released), and Cr, Sr and Zn (15% released). With gastric juice, 26% of As, Cr, Cu, Ni and Sb, and 77% of Zn, Sr and Pb were released on average. With lung fluid, 56 h leaching was as follows: Sb, 1.1%; As, 2.2%; Cr, 78%; Cu, 9%; Ni, 62%; Pb, 61%; Sr, 46%; V, 32%; and Zn, 89%. The high bio-accessibility of Pb in gastric juice and lung fluid may pose a health risk if such APM is inhaled or swallowed.