| Background: Expansion of the global market for electrical and electronic products continues to accelerate, and the rapid technologic development, decrease in prices, has decreased the lifespan of the products, which has resulted in a corresponding explosion in electronic scrap. This situation creates a large volume of obsolete electrical and electronic devices termed e-waste which if not properly handled can be a source of pollutants posing a risk to the environment and humans. Guiyu, China is famous for its involvement in processing primitive electronic-waste (e-waste). Persistence toxic substances such as polybrominated diphenyl ethers (PBDEs) are continually released to the environment. These extremely hazardous and dangerous e-waste recycling operations cause heavy pollution of air, water and soil in Guiyu, which also poses a threat to the health of the local people. PBDEs are a group of brominated compounds that have been widely used as brominated flame retardants for several decades because they provide long escape times in case of fire, which saves lives and reduces damage from fire. Despite their societal benefits, PBDEs seem to pose a threat to the environment and people. Still, insufficient knowledge exists on the potential adverse effects of PBDEs on public health. Human samples such as serum/plasma, milk, and adipose tissue have been used to evaluate the extent of human exposure to PBDEs. To date, most of these reports are from Europe and North America. However, no studies have reported on PBDE levels in umbilical cord blood (UCB) in e-waste recycling areas and their health effects on neonates in China.Objective: We aimed to evaluate the PBDE exposure of neonates from Guiyu, China, and a control area, Chaonan, China, through umbilical cord blood (UCB), the health effects, and relevant factors contributing to PBDE concentrations.Methods: We enrolled 167 healthy pregnant women as participants (108 from Guiyu and 59 from Chaonan), who voluntarily donated UCB after birth. The study protocol was approved by the Human Ethical Committee of Shantou University Medical College, China. All participants gave their written informed consent after receiving detailed explanations of the study and potential consequences prior to enrollment. Questionnaires were addressed to collect information on potential routes of exposure to PBDEs, as well as general demographic and health parameters, and UCB was collected shortly after birth from the pregnant women from Guiyu and Chaonan between May and July 2007.Serum samples were prepared by liquid-liquid extracting methods. The lipid content of the serum was determined by gravimetric methods after solvent evaporation. Lipid was dissolved with n-hexane and washed with H2SO4,and then cleaned up with a silica/sulfuric acid column.PBDE congeners (including BDE-28, -47, -99, -100, -153, -154, -183, and -209) were determined by Agilent 7890A gas chromatography coupled with 5975C mass spectrometry (Agilent Technologies, USA) and negative chemical ion analysis. Auto splitless injection onto a J&W Scientific DB-5 MS capillary column (30 m×0.25 mm i.d., 0.25μm film thickness) was used for the determination of less-brominated PBDE congeners, with helium (1 mL min-1) used as the carrier gas. Methane was used as a buffer gas in the NCI mode. The ion source, quadrupole and interface temperatures were set to 200, 150 and 280℃, respectively. The same conditions were used with a 15 m DB-5 HT capillary column (0.25 mm i.d., 0.1μm film thickness) for the analysis of BDE-209. Retention times for PBDE congeners were established with standard solutions. In addition, ion fragments at 79 and 81 m/z([Br]?) were monitored for less-brominated PBDE congeners, and 79, 81, 486.7, and 488.7 m/z for BDE-209. Oven temperature was ramped from 80℃(1 min) to 310℃(8 min) at 20℃/min for less-brominated PBDE congeners, and from 110℃(1 min) to 310℃(5 min) at 20℃/min for BDE-209. For every sequence of 8 samples, a solvent blank and a procedural blank were added to ensure that the samples and the analysis process were free of contamination.Data are expressed as median and ranges. We defined∑PBDE as the serum sum of congeners: BDE-28, -47, -99, -100, -153, -154, -183, and -209. The mean congener contribution to the∑PBDE was calculated as the average of congener contribution to the∑PBDE of each sample based on molar concentration. The Mann-Whitney U and Kruskal Wallis H tests were used because of the nonnormal distribution of the PBDE data. Potential associations between PBDE concentrations and related factors were explored by Spearman correlation analysis. Multiple stepwise regression analysis was used to evaluate factors related to PBDE concentrations. P values were calculated by the chi-square test for categorical data. Statistical analyses involved use of SPSS v13.0 (SPSS Inc., Chicago, IL, USA) and Microsoft Excel. A p<0.05 was considered statistically significant. Results: A total of 108 women from Guiyu and 59 women from Chaonan were enrolled and completed the questionnaires. A total of 102 women from Guiyu and 51 women from Chaonan provided UCB samples after giving birth. The pregnant women from Guiyu had a lower educational level, higher tea consumption and longer time on the road every day than did women from Chaonan. The total PBDE concentration was higher in UCB from Guiyu than in that from Chaonan (median 13.84, range 1.14 to 504.97 ng g-1 lipid; vs. 5.23, range 0.29 to 363.70 ng g-1 lipid) (P<0.05). Also, median individual congener concentrations, with the exception of BDE-209, were higher in UCB samples from Guiyu than from Chaonan samples (P<0.05). BDE-28, -47 and -183 were detected in all samples from Guiyu and Chaonan, and the detection frequencies of other congeners were all higher in UCB samples from Guiyu than from Chaonan samples (99.02%, 88.24%, 95.10%, 72.55%; vs. 70.59%, 72.55%, 82.35%, 35.29% for BDE-99, -100, -153, and -154, respectively, all P<0.05), except for BDE-209 (57.84% vs. 56.86%, P=0.908). BDE-209 was the dominant PBDE congener, followed by BDE-47, -153, and -28. We found some highest PBDE concentrations, largely contributed by BDE-209, in some samples in our study. When we compared our data with that from UCB concentrations around the world, the median concentrations of PBDEs in Guiyu samples were higher than those reported in Europe and other areas in China, but still lower than some data from the United States.Residing in Guiyu, which is involved in e-waste recycling and residence also used as a family workshop were significant factors contributing to PBDE concentrations in UCB. UCB samples from mothers involved in e-waste recycling showed higher concentrations of PBDE congeners than did UCB from women in the control region, especially for low-brominated congeners such as BDE-28, -47 and -99. We found high concentrations of some PBDE congeners (BDE-28, -47, -99, and -100) in UCB from the pregnant women living in houses also served as workshops in Guiyu. PBDE concentrations did not differ by sex or delivery mode (all P>0.05). Neonates from Guiyu and Chaonan did not differ in height, weight, gestational age, delivery mode, sex, or premature delivery rate (all P>0.05), but mean Apgar score in Guiyu was lower than that in Chaonan (P=0.001). Among the 108 births from Guiyu there were 8 stillbirths and one case of anencephalus. PBDE levels significantly differed in neonates by normal birth and still birth, low birth weight and premature delivery (P<0.05). Conclusions:(1) This is the first study concerning PBDE levels in UCB samples and their effect on neonate health, involving investigation by questionnaire, birth health checks and detection of blood PBDE levels. We studied a vulnerable population of neonates with exposure to multiple hazardous chemicals in an e-waste recycling area. The total PBDE concentration was higher in UCB from Guiyu than in that from Chaonan. Except BDE-209, both concentrations and detection frequencies of other 7 PBDE congeners in Guiyu samples were higher than in Chaonan samples.(2) Except for BDE-209, BDE-47 was the dominant congener and was detected in all blood samples, following by BDE-28, BDE-153 and BDE-183.(3) In this study, the mothers'residence in Guiyu for years and being involved in e-waste recycling largely contributed to PBDE concentrations in UCB samples; other significant factors were the house also being the family workshop and the husband being involved in e-waste recycling.(4) PBDEs at levels determined in this study may have affected the neonates'health and development. This finding provides some clues for the potential health risk of PBDEs to humans. Prenatal exposure to PBDEs may have affected neonates'health. The biological effects and the potential health risks of PBDEs still need to be evaluated in random studies with larger samples.
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