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Considering the negative effect of lead (Pb) on children's neurodevelopment, Pb exposure should be minimized to the lowest extent possible, though the blood Pb (BPb) concentrations in Japanese children are among the lowest in the world. To identify the sources of Pb in blood, isotope ratios (IRs: 207 Pb/ 206 Pb and 208 Pb/ 206 Pb) of Pb (PbIR) in whole blood from eight Japanese children were measured by multi-collector ICP mass spectrometry. Further, samples of house dust, soil, duplicate diet, and tobacco, collected from home environments, were also measured and were compared with PbIR of blood case by case. The relative contribution of Pb in the home environment to BPb were estimated by linear programming (finding an optimal solution which satisfy the combination of IRs and intakes from various sources) when appropriate. Source apportionment for three children could be estimated, and contributions of diet, soil, and house dust were 19-34%, 0-55%, and 20-76%, respectively. PbIR for the remaining five children also suggested that non-dietary sources also contributed to Pb exposure, though quantitative contributions could not be estimated. Non-dietary sources such as soil, house dust, and passive tobacco smoke are also important contributors to Pb exposure for Japanese children based on PbIR results.

The radiation dose effects due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident are of public concern. Although indoor dust is an important exposure route for some hazardous chemicals, the radiation exposure dose from the radioactive caesium (Cs) in it has not been well investigated. Hence, in this study, we measured the radioactive Cs in the indoor dust of private houses in order to estimate the resulting human exposure. We collected vacuum cleaner dust twice (in April and June 2012, n = 250 and 241, respectively) in the prefectures of Chiba and Ibaraki, from houses located 150-200 km south from the FDNPP. The activity concentrations of 134 Cs and 137 Cs in the indoor dust were measured using germanium γ-ray detectors, and the exposure dose was calculated and the household-to-household variations were analysed. The median activity concentrations of 134 Cs + 137 Cs in the indoor dust collected in April and June were 1470 and 1340 Bq kg -1 , respectively. The median committed effective doses via indoor dust ingestion were estimated as 0.73, 0.66, and 0.43 × 10 -3  mSv year -1 , and those via inhalation were estimated as 0.03, 0.04, and 0.06 × 10 -3  mSv year -1 for one- and ten-year-old children and adults, respectively. Those were much smaller than the annual dose limit of 1 mSv year -1 , which was set as a goal to be achieved in the a few years or decades (clear period has not been set). Within the detached houses, multiple regression analysis showed that wet wiping of floor was a significant reduction factor of the Cs concentration in dust; however, the small determination coefficient implies the presence of factors that were not considered in this study., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The levels of 25 elements in house dust collected from 100 general Japanese residences were measured. Factor analysis was applied on the multi-element data to explore source of Pb (median concentration 49.1 mg/kg) in house dust. Six factors were extracted and Pb was found to have great loading on the fifth factor with Sb and Sn, suggesting solder (Sn), and plastic and metals (Sb) may be the sources of Pb in the house dust of Japanese residences. No significant loading was found on soil-related factors indicating non-significant contribution of Pb in track-in soil. Seven heavy metals (Cd, Cu, Mo, Pb, Sb, Sn, and Zn) were found in house dust at >10 times more condensed than crustal abundance. Health risk of these elements to children via the ingestion of house dust was estimated based on the comparison with tolerable daily intake and found to be non-significant for most of the elements., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Phthalates are widely used as plasticizer and associated with various health issues. Recently, non-phthalate plasticizers are replacing phthalates; however, the exposure to these substances and the risk in Japan is unclear. In this study, we assessed the concentrations of phthalates, non-phthalate plasticizers, and phthalate degradation products in house dust and determined their respective exposure risks via oral and dermal routes. Twelve phthalates, seven non-phthalate plasticizers, and two degradation products were determined in the house dust obtained from 100 Japanese homes. The median concentration of di(2-ethylhexyl) phthalate (DEHP), accounting for 85 % of the total concentration of phthalates and non-phthalate plasticizers detected in this study, was 2.1 × 103 μg/g of dust. Apart from DEHP, diisononyl phthalate (DINP) and di(2-ethylhexyl) terephthalate (DEHT) were the most abundant in the house dust, accounting for 6.2 % (median: 1.7 × 102 μg/g of dust) and 6.1 % (median: 1.7 × 102 μg/g of dust) of the total concentrations, respectively. DEHP and DEHT concentrations in house dust were higher in apartment and small houses (floor area: ≤30 m2 or 31–60 m2 for DEHP and 31–60 m2 for DEHT) than in detached and large houses (floor area: ≥121 m2). Conversely, di-n-butyl phthalate (DnBP) concentrations were significantly higher in detached and large houses (floor area: ≥121 m2) than in apartment and small houses (floor area: ≤30 m2). The total hazard quotient (HQ), using the maximum concentration in house dust, revealed that oral and dermal exposure to house dust was 1.3 × 10-6–0.11 for adults (all substances) and 1.6 × 10-5–2.2 × 10-2 for preschool children (except for DnBP and DEHP), suggesting no risk. The HQs for DnBP and DEHP exposure via house dust for preschool children using the maximum values were 0.46 and 1.2, and 6.0 × 10-3 and 0.18 using the median values, indicating that risk of DEHP exposure should be exhaustively determined by considering other exposure routes that were not evaluated in this study, such as diet. [ABSTRACT FROM AUTHOR]