Composition of heavy metals in indoor dust and their possible exposure: a case study of preschool children in Malaysia

The aim of this study is to determine the levels of selected heavy metals (Pb, Zn, Cd, Fe and Cr) at ten preschools in Selangor, Malaysia. Dust samples from the interior of classrooms and surface soils were collected using soft paint brushes while Kimwipes were used to collect samples of dust from interior walls and children's palms. Heavy metals in the dust samples were determined using inductively coupled plasma mass spectrometry (ICP-MS). The concentrations of the selected heavy metals in the indoor dust were dominated by Fe with a concentration of 4,801 +/- 1,873 mu gg(-1) followed by Pb > Zn > Cr and Cd with concentration of 253.5 +/- 83.2, 144.9 +/- 73.4, 11.9 +/- 6.8 and 0.23 +/- 0.10 mu gg(-1), respectively. Fe also had the highest concentration of all the heavy metals investigated in the samples taken of soil dust (8,225 +/- 6,800 mu gg(-1)), the interior walls (1,865 +/- 756 mu gm(-2)) and children's palms (3,882 +/- 3,401 mu gm(-2)). Using enrichment factor (EF) analyses, Pb, Zn and Cd in the indoor dust were found contributed by anthropogenic factors while the same was true for Zn, Cd and Cr in the indoor wall and children's palm samples.