Lead in Playground Soil: Exposure Estimation of Children via Ingestion and Contamination Source

概要

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Lead exposure of children via soil ingestion has never been closely examined in Japan. We determined the lead concentrations in sand and soil samples collected from some public playgrounds in Tokyo Metropolitan Area and estimated lead intake via soil ingestion among children. The mean lead concentration of the soil of 149μm fraction was 46.4μg/g; lead concentrations of play area soil and sand samples (149μm) collected from 25 playgrounds ranged from 11.7μg/g to 248μg/g. An average daily intake of 9.28μg lead was estimated; this amount of lead intake via soil ingestion alone covers 14% of the Provisional Tolerable Weekly Intake (PTWI) of 25μg/kg of body weight set by FAO/WHO. Moreover, the weekly lead intake through soil ingestion could be as high as 72% of PTWI when children ingest soil containing 200μg/g lead. Stable isotope ratios (IRs) analysis of selected soil samples and comparison with the IRs of probable sources were carried out. The IRs of soil samples with lead concentrations higher than 100μg/g had a similar distribution to the gasoline-lead used in Japan, indicating that atmospheric particulates deposited in the past remain in surface soil despite the fact that leaded-gasoline has not been used in Japan for transportation since the 1980s.
日本環境化学会の論文