| Children living in certain lead-contaminated areas of China continue to have elevated blood lead levels.The health risks and source apportionment of children lead exposure remain the focus of public and scientific attention.Since blood samples from children are not readily available,there are still challenges in accurately identifying the source of lead exposure.Domestic dogs have been recognized as "sentinels" for the monitoring of lead poisoning in humans,particularly in children.However,there is a lack of reliable evidence as to whether blood lead from domestic dogs can be used as an alternative biomarker to indicate the pathways and sources of lead exposure in children.In this study,the areas with lead emissions from industrial sources(around smelters and coking plants),domestic sources(using coal as the primary household fuel,considered as coal-burning area),and a general rural area without obvious sources of lead pollution in China were selected as case study locations.A total of 88 pairs of children and domestic dogs from the same households were included,and their blood and external exposure samples(food,drinking water,soil,dust,and PM2.5)were collected.The blood lead levels and lead isotope ratios were then measured in children and domestic dogs,respectively,and their correlations were explored.Based on lead isotope fingerprinting technology,this study established a method to identify the pathways and sources of lead exposure in children and dogs,constructed the quantitative models using domestic dogs’ blood lead as an indicator of children’s blood lead levels and lead exposure pathways and sources,and verified its applicability.The main research findings are as follows:(1)There were regional differences in blood lead levels between children and domestic dogs(p<0.01).The blood lead levels of children in coal-burning area(median:8.43 μg/dL)were all higher than 5 μg/dL.Domestic dogs and children from the same households had similar dietary and drinking water patterns and behavioral characteristics such as soil/dust ingestion.(2)A high correlation was found between the blood lead levels of children and those of domestic dogs(Coal-burning area:R2=0.865;General rural area:R2=0.687).Linear regression models(both simple and multiple)were established in coal-burning area using domestic dog blood lead as an indicator of children’s blood lead levels,with good fitting degree(R2=0.820 and 0.855,respectively).These models are also applicable in other lead-polluted areas(smelting and coking areas)and general rural area.(3)There was a high correlation between the lead isotope ratios(207Pb/206Pb and 208Pb/206Pb)in the blood of children and domestic dogs(Coal-burning area:R2=0.856 and 0.876;General rural area:R2=0.889 and 0.895).Food contributed 83.1%and 76.9%of the lead exposure for children and domestic dogs in coal-burning area,respectively,and 95.4%and 97.8%for those in general rural area,indicating similar lead exposure pathways and environmental pollution sources(domestic coal)for children and dogs in both areas.(4)The quantitative model used the domestic dogs’ blood lead isotope ratios to indicate children’s lead exposure sources in coal-burning area has good fit(R2>0.89).Validation results showed that the predicted main lead exposure pathway for children in general rural area was food ingestion,with the so.urce being domestic coal use,consistent with the results of source apportionment of children’s blood lead exposure conducted locally.The models are also able to predict the main lead exposure pathway and source for children in smelting and coking areas. |
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