| Background: Electrical and electronic equipments pervade modern lifestyles and their consumption is growing rapidly all over the world. Quick obsolescence and newer functionalities of these products are resulting in huge quantities of Waste Electrical and Electronic Equipment (WEEE) or electronic and electric waste (e-waste). Due to the contained hazard substances, such as heavy metals and other chemicals, e-waste may cause a threat to the environment and human health during the management and processing. Guiyu in Southern China, is one of the biggest destinations of e-waste in the world and has nearly 20 years of disposal and recycling history. Several studies have reported the soaring levels of toxic heavy metals and persistent organic pollutants (POPs) such as polycyclic aromatic hydrocarbons (PAHs) and polybrominated diphenyl ethers (PBDEs) contaminants in workplace environment, surrounding soil and water sources of Guiyu. Neonates are considered highly susceptible to chemical toxicants because of immaturity of developing immune systems, rapid development of fetal organs and higher absorption compared with adults. Recently, the relationship between prenatal exposure to toxic substances and adverse birth outcomes attracts worldwide attention. However, no studies have reported on heavy metals in placenta, PAHs levels in umbilical cord blood (UCB) in e-waste recycling areas and their health effects on neonates in China.Objective: We aimed to investigate lead (Pb), cadmium (Cd), chromium (Cr), nickel (Ni) and PAHs exposure of neonates from Guiyu and Chaonan, through placenta and umbilical cord blood (UCB), and explore the health effects, and relevant factors.Methods: We enrolled 253 healthy pregnant women as participants (127 from Guiyu and 126 from Chaonan), who voluntarily donated placenta and 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 heavy metals and PAHs, as well as general demographic and health indicators. Placenta and UCB were collected shortly after birth from the pregnant women from Guiyu and Chaonan between September in 2008 and May in 2009. The concentrations of Pb, Cd, Cr, and Ni in placental and UCB were determined by graphite furnace atomic absorption spectrometry (GFAAS). 16 priority United States Environmental Protection Agency (USEPA) PAHs were determined by Agilent 7890A gas chromatography coupled with 5975C mass spectrometry (GC-MS) with electronic ionization in select ion monitoring mode.Results: A total of 126 women from Guiyu and 127 women from Chaonan were enrolled in the study and completed the questionnaires. None of the mothers reported smoking and drinking alcohol in the year prior to pregnancy and during the pregnancy. Neonates from Guiyu and Chaonan did not differ in height, weight, gestational age, delivery mode, sex, Apgar, or premature delivery rate (all p>0.05).1. The pregnant women from Guiyu had a lower educational level, and poorer housing conditions than did women from the control area. Of the 253 participants, only 8 women from Chaonan had completed a college education. Therefore, they lived under relative poverty economic situations.2. The median UCB lead levels (UCBLLs) of women from Guiyu was 110.5μg/L, with interquartile range from 79.2 to 141.4μg/L, while UCBLLs from Chaonan with interquartile range from 34.4 to 78.5μg/L with a median of 49.7μg/L (P<0.01). We also observed that in Guiyu, 64.3% of women (81/126) had UCBLLs>100μg/L, compared with 15.7% (20/127) in Chaonan (P<0.01). We also found a negtive correlation between UCBLLs and neonates'birth weight . Elevated UCB cadmium levels (UCBCLs) from Guiyu were also observed in this study. UCBCLs from Guiyu with interquartile ranged from 1.3 to 4.0μg/L with a median of 2.47μg/L, whereas UCBCLs from Chaonan with interquartile ranged from 0.2 to 1.2μg/L with a median of 0.4μg/L (P<0.01). 57.9% (73/126) of women from Guiyu had UCBCLs>2μg/L, compared with 19.7% (25/127) in Chaonan (P<0.01). A significant relationship between elevated UCBCLs and decreased gestational age was found in this study. However, no significant differences of UCB chromium and nickel levels were found between the two groups. Spearman correlation analyses showed that women residence in Guiyu and work involvement in e-waste correlated with elevated UCBLLs, UCBCLs.3. The interquartile range of placental concentration of lead (PCPb) from Guiyu was 103.3 to 859.0 ng/g with a median of 301.4 ng/g, whereas PCPb from Chaonan was 78.4 to 491.4 ng/g with a median of 165.82 ng/g (P<0.01). We also observed that in Guiyu, 41.6% of women (42/101) had PCPb>500 ng/g wt (wet weight), compared with 24.4% of women (29/119) in Chaonan (P<0.01). No significant differences of placental concentration of cadmium and chromium were found between the two groups. However, we found that with the increasing PCCd, a decreased birth weight trend was found in this study. In contrast, placental concentration of nickel (PCNi) was higher in samples from Chaonan (median 14.30, interquartile range 6.5-43.6 ng/g) than in Guiyu samples (median 7.64, interquartile range 3.9-18.1 ng/g) (P<0.01). A negative correlation between PCNi and gestational age was also found. Spearman correlation analyses showed that there was correlation between PCPb and residence in e-waste recycling area.4. The total 16 priority USEPA PAHs in UCB of women didn't differ between two groups. However, women from Guiyu had higher levels of 7 dioxin-like PAHs except Chr when compared with Chaonan. The interquartile range of total 7 dioxin-like PAHs from Guiyu was 70.76 to 188.97 ppb with a median of 108.05 ppb, while total 7 dioxin-like PAHs from Chaonan was 56.93 to 142.94 ppb with a median of 79.55 ppb (P<0.05). Significant differences in Ant, BaA, and Chr levels between UCB samples from normal births and those with adverse birth outcomes. After Spearman correlation analysis, we found that low molecular PAHs such as Ace, A, and Ant correlated with women residence in Guiyu and work related to e-waste.Conclusions: Neonates born in Guiyu had significant higher levels of lead, cadmium and 7 dioxin-like PAHs in UCB, elevated PCPb and decreased PCNi was also found in women from Guiyu. Parents residence in Guiyu, length of residence and work related to e-waste correlated with higher exposure to toxic substances including heavy metals and persistent organic pollutants. Environmental pollution, resulted from unregulated e-waste recycling activities, may contribute to elevated PCPb and PAHs in neonates born in Guiyu. |
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