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Lead exposure in young children over a 5-year period from urban environments using alternative exposure measures with the US EPA IEUBK model – A trial
Environmental Research ( IF 7.7 ) Pub Date : 2017-12-26 , DOI: 10.1016/j.envres.2017.10.040
Brian Gulson , Alan Taylor , Marc Stifelman

The US Environmental Protection Agency (EPA) Integrated Exposure Uptake Biokinetic (IEUBK) model has been widely used to predict blood lead (PbB) levels in children especially around industrial sites. Exposure variables have strongly focussed on the major contribution of lead (Pb) in soil and interior dust to total intake and, in many studies, site-specific data for air, water, diet and measured PbB were not available. We have applied the IEUBK model to a comprehensive data set, including measured PbB, for 108 children monitored over a 5-year period in Sydney, New South Wales, Australia. To use this data set, we have substituted available data (with or without modification) for standard inputs as needed. For example, as an alternative measure for soil Pb concentration (μg/g), we have substituted exterior dust sweepings Pb concentration (μg/g). As alternative measures for interior dust Pb concentration (μg/g) we have used 1) 30-day cumulative petri dish deposition data (PDD) (as µg Pb/m2/30days), or 2) hand wipe data (as μg Pb/hand). For comparison, simulations were also undertaken with estimates of dust Pb concentration derived from a prior regression of dust Pb concentration (μg/g) on dust Pb loading (μg/ft2) as concentration is the unit specified for the Model. Simulations for each subject using observed data aggregated over the 5-year interval of the study, the most usual application of the IEUBK model, showed using Wilcoxon tests that there was a significant difference between the observed values and the values predicted by the Model containing soil with hand wipes (p < 0.001), and soil and PDD (p = 0.026) but not those for the other two sets of predictors, based on sweepings and PDD or sweepings and wipes. Overall, simulations of the Model using alternative exposure measures of petri dish dust (and possibly hand wipes) instead of vacuum cleaner dust and dust sweepings instead of soil provide predicted PbB which are generally consistent with each other and observed values. The predicted geometric mean PbBs were 2.17 ( ± 1.24) μg/dL for soil with PDD, 1.95 ( ± 1.17) μg/dL for soil with hand wipes, 2.36 ( ± 1.75) μg/dL for sweepings with PDD, and 2.15 ( ± 1.69) for sweepings with hand wipes. These results are in good agreement with the observed geometric mean PbB of 2.46 ( ± 0.99) μg/dL. In contrast to all other IEUBK model studies to our knowledge, we have stratified the data over the age ranges from 1 to 5 years. The median of the predicted values was lower than that for the observed values for every combination of age and set of measures; in some cases, the difference was statistically significant. The differences between observed and predicted PbB tended to be greatest for the soil plus wipes measure and for the oldest age group. Use of ‘default dust’ values calculated from the site-specific soil values, a common application of the IEUBK model, results in predicted PbB about 22% (range 0 to 52%) higher than those from soil with PDD data sets. Geometric mean contributions estimated from the Model to total Pb intake for a child aged 1–2 years was 0.09% for air, 42% for diet, 5.3% for water and 42% for soil and dust. Our results indicate that it is feasible to use alternative measures of soil and dust exposure to provide reliable predictions of PbB in urban environments.



中文翻译:

使用美国EPA IEUBK模型采用替代暴露措施,对5年内城市环境中幼儿的铅暴露进行试验

美国环境保护局(EPA)的综合暴露吸收生物动力学(IEUBK)模型已被广泛用于预测儿童,尤其是工业场所周围儿童的血铅(PbB)水平。暴露变量主要集中在土壤和室内粉尘中铅(Pb)对总摄入量的主要贡献上,在许多研究中,尚无针对特定地点的空气,水,饮食和测得的PbB数据。我们已将IEUBK模型应用于包括在澳大利亚新南威尔士州悉尼进行的为期5年的监测的108名儿童的综合数据集,包括测得的PbB。要使用此数据集,我们根据需要将可用数据(有或没有修改)替换为标准输入。例如,作为土壤Pb浓度(μg/ g)的一种替代方法,我们用外部除尘剂Pb浓度(μg/ g)代替。2 /30天),或2)手擦拭数据(以μg铅/手)。为了进行比较,还对灰尘Pb浓度的估算进行了模拟,该估算值是根据灰尘Pb负荷(μg/ ft 2),因为浓度是为模型指定的单位。使用研究的5年间隔(IEUBK模型的最常见应用)中汇总的观察数据对每个受试者进行的模拟显示,使用Wilcoxon检验,观察值与包含土壤的模型所预测的值之间存在显着差异手动擦拭(p <0.001),土壤和PDD(p = 0.026),但其他两组预测变量则不包括,基于扫除和PDD或扫除和抹布。总体而言,使用陪替氏培养皿粉尘(可能还有手巾)的替代暴露措施代替真空吸尘器粉尘和灰尘清除剂代替土壤进行的模型模拟提供了预测的PbB,该值通常彼此一致且与观测值一致。预测的几何平均PbBs为2.17(±1。24)对于带有PDD的土壤,微克/分升;对于带有手拭纸的土壤,为1.95(±1.17)μg/ dL;对于带有PDD的抹布,其结果为2.36(±1.75)μg/ dL;对于使用抹布的抹地,为2.15(±1.69)这些结果与观察到的2.46(±0.99)μg/ dL的几何平均PbB高度吻合。与我们所了解的所有其他IEUBK模型研究相比,我们对1-5岁年龄段的数据进行了分层。对于年龄和测量的每种组合,预测值的中位数低于观察值的中位数;在某些情况下,差异具有统计学意义。对于土壤加湿巾测量值和最老的年龄组,观察到的PbB与预测的PbB之间的差异往往最大。使用根据特定地点的土壤值计算得出的“默认尘土”值,这是IEUBK模型的常见应用,与PDD数据集相比,预测的PbB约高22%(范围为0至52%)。根据模型估算,1-2岁儿童的总Pb摄入量的几何平均贡献为:空气0.09%,饮食42%,水5.3%和土壤和灰尘42%。我们的结果表明,在城市环境中使用土壤和粉尘暴露的替代措施来提供可靠的PbB预测是可行的。

更新日期:2017-12-26
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