ハウスダスト中鉛への室外要因の寄与：同位体分析による評価

抄録

House dust has been considered major source of lead for the Japanese. In this study isotope ratios of lead (²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb) were used for the apportionment of lead in house dust. ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb in house dust (＜250µm fraction of vacuum cleaner dust), soil (＜250 µm fraction of garden soil), and outdoor dust (exterior windowsill dust), sampled from 20 detached housings in Japan, were measured by ICP mass spectrometry after HNO₃/HClO₄/HF decomposition. Correlation of ²⁰⁷Pb/²⁰⁶Pb between house dust and outdoor dust was significant (r＝0.539, p＝0.023) while that between house dust and soil was not (r＝0.275, p＞0.05) indicating that a part of lead in house dust of residences of general Japanese was due to infiltration of outdoor dust. However, the correlation was rather weak (R²＝0.29) suggesting that exterior factors contribute less than interior factor(s). Identification of other factors than outdoor dust infiltration would be necessary for the reduction of levels of lead exposure via house dust ingestion.