Abstract
This study was carried out as a part of a project to identify the source(s) of Pb in indoor dust in dwellings in Japan. Because of unique features with regard to Pb in Japan - early phase-out of leaded gasoline and no tradition of painting the interior/exterior of houses - Japanese houses lack the definite Pb contamination sources (paint and leaded gasoline) that are known to occur in other developed countries. Indoor dust, outdoor dust and soil samples were collected from 41 households in Japan and Pb and Cd concentrations in the samples (<250 μm fraction) were measured by ICP mass spectrometry after HNO3/HC1O4/HF digestion. Median concentrations of Pb and Cd were 54.1 and 0.932 mg/kg, 31.7 and 0.563 mg/kg, and 153 and 1.74 mg/kg for indoor dust, soil and outdoor dust, respectively. The concentrations of Pb and Cd in indoor dust were lower than those previously and currently reported, indicating that dwellings in Japan are less contaminated with these metals than are those in other countries. Indoor dust Pb and Cd concentrations were only weakly correlated with outdoor metal concentrations and did not correlate with household variables (household type, presence/absence of smoker or pet, heating fuel and type of flooring). The results indicated that there were unknown factors that affect indoor dust metal concentrations in Japanese households.
