| Background and Objective Expansion of the global market for electrical and electronicproducts continues to accelerate, while the lifespan of the products is dropping, resulting in acorresponding explosion in electronic waste. These devices often contain a variety of toxicmetals (e.g., lead, cadmium), and these subsequently create substantial problems with regard tohandling, recycling and disposal of obsolete products. Unregulated disposal will bring manyproblems. At the present, however, the electronic wastes (e-wastes) recycling sector in manyplaces of our country remains largely unregulated. Guiyu in Shantou, Guangdong province is oneof the popular destinations of e-waste, which has more than 10 years' e-waste unregulateddisposal history. Guiyu has accommodated millions of tons of e-waste from overseas anddomestic a year, but the processes and techniques used during the recycling activities in Guiyuwere very primitive. The result was that many tons of e-wastes material and process residueswere dumped in local environment. It is not doubt that hazardous materials could be released frome-wastes through disposal or recycling processes with the threat to the health of local residents.Several studies have reported the soaring levels of toxic heavy metals and organic contaminantsin environment of Guiyu.Recently, the impacts on the health of heavy metals poisoning of children have been paid moreattention. But up to now, there is poorly studied on the heavy metals burden level of childrenaround the recycling site. Considering the potential heavy mental contamination in the localliving environment of Guiyu, we proposed that children living in Guiyu may have elevated bloodlevels of heavy metals (e.g., lead and cadmium) and thus may have impacted on their health. Inthis study, the local pre-school children in Guiyu were chosen and the body lead level andcadmium level were measured in two different periods, and the questionnaire was taken at thesame time. Furthermore, the genotype ofδ-aminolevulinic acid dehydratase (ALAD) gene thatwas contributed to lead genetic susceptibility was also studied. The aim of these research was toreveal the lead,cadmium burden level of children who lived in the electronic waste recyclingarea, Guiyu, Guangdong, China, and to discuss the effects of unregulated e-wastes recycling onchildren's health. Our study also could provide scientific parameters for evaluation the leadpollution level and pollution control in Guiyu area.Materials and Methods The children aged from 1 to 8 years old in Guiyu area were examined in this study, and children with same ages from Chendian, a non-pollution area, wereused as control. The blood lead level (BLL) and blood cadmium level (BCL) were measuredwith graphite atomizer absorption spectrophotometer in 2004 and 2006. Hemoglobin (Hgb) andphysical developmental indexes (height and weight, head and chest circumferences) were alsodetermined at the same time. Guestionnaires were taken to study the children's health and livingenvironmental situations. Furthermore, an assay based on the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique of restriction enzyme MspIwas used to determine the genotype of the ALAD gene, and the PCR expanding DNA productsof ALAD gene were also sequenced to confirm the results of RFLP. All the results of these twostudies were compared.Results 1. The means BLL of children from exposure group in 2004 and 2006 were (153.0±57.9)μg/L and (133.1±60.4)μg/L, respectively. And the children with BLL over 100μg/L,which was considered as high lead burden (HLB), were 81.8% in 2004, and 70.8% in 2006.Compared with the control group, both mean BLL and HLB rate in Guiyu group weresignificantly higher than that in control group during these two years studies (P＜0.01). Theresults were also shown that both BLL and HLB rate were increased with the age in the exposuregroup (P＜0.01). But the mean BLL and HLB rate in Guiyu group were reduced significantly in2006 compared to 2004 (P＜0.01). There were no difference could be found between boys andgirls in physical indexes and Hgb level in Guiyu groups. (P＞0.05). Three risk factors, whichwere the work correlated with e-wastes that father took, the time that children play in the openair, and passive smoking, would cause children HLB.2. The median BCL of children from exposure group in 2004 and 2006 were 1.73μg/L and1.32μg/L, respectively. And the children with BCL over 5μg/L were 1.8% in 2004 and 1.9% in2006. Compared with the control group, both the median BCL and the rate that over 5μg/L inGuiyu group were significantly higher than that in control group during these two years studies(P＜0.01). The results were also shown that the median BCL in Guiyu group were reducedsignificantly in 2006 compared to 2004 (P＜0.01). Correlation analysis found that the work correlatedwith e-wastes that father took and the time that children play in the open air, the house gets closeto road were three kinds of risk factors to children's BCL.3. A polymorphic enzyme exists in the ALAD gene of the electronic wastes recycling area,Guiyu, Guangdong province and the ALAD2 allele frequency was lower than in whole country.Furthermore, no statistic correlation between the distribution of ALAD alleles and the blood leadlevel could be found in this research. Conclusion High BLL and high BCL were found in most children who lived in the electronicwaste recycling area. Although the means BLL, BCL of children were decreased in 2006 whencompared with 2004 in this area, it was still much higher than that of nationwide, especially thechildren's BLL. There were four kinds of risk factors correlated to children's BLL and BCL: Thework related to e-wastes their father took, the time that children play in the open air, and thehouse gets close to road and passive smoking. In this area, Children are genetically lesssusceptible to lead toxicity than others, Furthermore, there was no relationship could be foundbetween genetic susceptibility of ALAD polymorphism and BLL of children in Guiyu. Under thishereditary property, children still in the high BLL. So it showed that unregulated e-wastesdisposal has affected the lead and cadmium levels of children in electronic wastes recyclingdistrict. The environmental heavy metals pollution caused by recycled electronic waste stronglyaffects the children health.
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