Department of Earth and Environmental Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW, 2109, Australia; Ministry of Education-Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200092, PR China.
Department of Earth and Environmental Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW, 2109, Australia.
Environ Res. 2020 Jul;186:109357. doi: 10.1016/j.envres.2020.109357. Epub 2020 Mar 11.
Broken Hill, the oldest silver (Ag)-zinc (Zn)-lead (Pb) mining community in Australia, has a legacy and ongoing problem of environmental Pb exposure that was identified as early as 1893. To reduce Pb exposure risks, identifying potential exposure pathways and related factors is a critical first step. This study examined blood lead (PbB) levels of children ≤60 months old (n = 24,106 samples), along with Pb concentrations in corresponding soil (n = 10,160 samples), petri-dish dust (n = 106 houses) and ceiling dust (n = 80 houses) over a 25-year period from 1991 to 2015. Regression analysis was used to examine the relationships between environmental Pb sources and children's blood lead (PbB) outcomes. Analysis of the dataset showed Aboriginal children in Broken Hill had a geometric mean PbB of 7.4 μg/dL (95% CI: 6.7-7.4) being significantly higher (p < 0.01) than non-Aboriginal children (PbB 6.2 μg/dL, 95% CI: 6.2-6.3) for all years between 1991 and 2015. Children at the age of 24-36 months had a higher PbB compared with other age groups. Higher PbB levels were also statistically associated with lower socio-economic status and children living in houses built before 1940 (p < 0.01). Blood Pb was also significantly correlated with both soil Pb and indoor petri-dish dust Pb loadings, confirming that these are important pathways for exposure in Broken Hill. A 100 mg/kg increase in soil Pb was associated with a 0.12 μg/dL increase in childhood PbB. In addition, PbB concentrations increased with indoor petri-dish dust Pb loadings (i.e., 0.08 μg/dL per 100 μg/m/30 days). The 25-year data show that the risk of exposure at ≥ 10 μg/dL was seemingly unavoidable irrespective of residential address (i.e., children of all ages presenting with a ≥10 μg/dL across the whole city area). In terms of moving forward and mitigating harmful early-life Pb exposures, all children aged 24-36 months should be prioritised for feasible and effective intervention practices. Primary intervention must focus on mitigating contemporary ongoing dust emissions from the mining operations and the associated mine-lease areas along with household soil remediation, to help prevent recontamination of homes. Additional practices of dust cleaning using wet mopping and wiping techniques, vacuuming of carpets and furnishings, ongoing monitoring of children and household dust remain important but short-lived abatement strategies. Overall, the key goal should be to eliminate risk by removing contamination in the wider environment as well as in individual homes.
布罗肯山是澳大利亚历史最悠久的银（Ag）-锌（Zn）-铅（Pb）矿区，一直存在环境 Pb 暴露的遗留问题和持续问题，早在 1893 年就已被发现。为了降低 Pb 暴露风险，确定潜在的暴露途径和相关因素是至关重要的第一步。本研究调查了 1991 年至 2015 年间 25 年间 24106 名≤60 个月大的儿童（n）的血铅（PbB）水平，以及 10160 个样本的相应土壤（n）、培养皿灰尘（n=106 个房屋）和天花板灰尘（n=80 个房屋）中的 Pb 浓度。使用回归分析来检验环境 Pb 来源与儿童血铅（PbB）结果之间的关系。对数据集的分析表明，布罗肯山的土著儿童血铅中位数为 7.4μg/dL（95%CI：6.7-7.4），明显高于（p<0.01）非土著儿童（PbB 6.2μg/dL，95%CI：6.2-6.3），在 1991 年至 2015 年期间所有年份均如此。24-36 个月大的儿童血铅水平高于其他年龄组。较低的社会经济地位和生活在 1940 年前建造的房屋中的儿童血铅水平也与较高的 PbB 水平呈统计学相关（p<0.01）。血铅与土壤 Pb 和室内培养皿灰尘 Pb 负荷均呈显著相关，证实这些是布罗肯山 Pb 暴露的重要途径。土壤 Pb 增加 100mg/kg，儿童血铅 PbB 增加 0.12μg/dL。此外，室内培养皿灰尘 Pb 负荷增加，血铅浓度也会增加（即，室内培养皿灰尘 Pb 负荷每增加 100μg/m/30 天，血铅浓度增加 0.08μg/dL）。25 年的数据表明，无论居住地址如何（即整个城市地区所有年龄段的儿童血铅均≥10μg/dL），接触≥10μg/dL 的风险似乎都不可避免。为了减少有害的儿童早期 Pb 暴露，所有 24-36 个月大的儿童都应优先考虑采取可行和有效的干预措施。首要干预措施必须集中在减轻采矿作业和相关矿区的持续粉尘排放以及家庭土壤修复，以帮助防止家庭再次受到污染。使用湿拖和擦拭技术清洁灰尘、清洁地毯和家具、持续监测儿童和家庭灰尘等额外措施仍然是重要的，但只是短期的缓解策略。总的来说，关键目标应该是通过消除更广泛环境和个别家庭中的污染来消除风险。
