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题名: 典型电子垃圾循环区母乳中多氯联苯(PCBs) 污染及浓度 变化趋势
作者: 吕全霞
学位类别: 硕士
答辩日期: 2015-05
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 李兴红
关键词: 母乳,婴儿,多氯联苯,暴露风险,变化趋势,breast milk, breast-fed infant, PCBs exposure risk, concentration change
其他题名: Contamination Situation and Concentration Tendency of Polychlorinated Biphenyls (PCBs) in Breast Milk During Lactation from Typical E-waste Recycling Areas in China
学位专业: 环境科学
中文摘要:     本论文以浙江省台州市LQ 和WL 电子垃圾循环区域为研究现场,对当地人群母乳中多氯联苯(PCBs)的污染现状进行了评估;进一步,研究了哺乳期连续母乳中PCBs 浓度随哺乳时间延长的变化趋势,并探讨了母亲哺乳期体重变化与浓度变化之间的相关性。
    母乳中PCBs 污染水平的研究结果表明,LQ 本地人群(n=27)、WL 本地人群(n=48)及在台州居住不足5 年的外地人群(n=15)母乳中Σ8PCBs 中值浓度分别为195 ng·g-1 脂重(lw),98.4 ng·g-1 lw 和32.0 ng·g-1 lw。LQ 和WL本地人群母乳中Σ8PCBs 浓度显著高于在台州居住不足5 年的外地人群(p<0.001),也高于浙江省及中国背景区域水平。CB-118、CB-153 和CB-138是台州母乳中最主要的三种同类物,与台州膳食样本中PCBs 的指纹特征类似。
    台州本地人群婴儿通过饮用母乳日摄入的PCBs 量接近或略高于加拿大卫生部建议的成人对PCBs 日耐受量,表明该区域本地人群母乳喂养的婴儿处于较高的PCBs 暴露风险中。
哺乳期连续母乳中PCBs 浓度随哺乳时间延长的变化趋势研究发现,在产后“1-210 天”收集的系列母乳样本中,PCBs 的浓度在一定范围内波动(最大变化80%),并没有呈现数倍的变化。因此,如果现实采样条件受到限制,采集哺乳期“1-210 天”内母乳样本评估母亲/婴儿PCBs 身体负荷,不会对评估结果造成数倍的偏差。不过,配对样本T 检验发现,“1-7 天(初乳)”PCBs 浓度水平与“8-20 天”、“21-210 天”母乳的浓度有显著差异,而“2-210 天”时
间段内母乳PCBs 浓度并无明显变化。这个结果说明,母乳采集时间段的不同会导致母乳中PCBs 浓度水平的显著差异;在评估研究人群母亲/婴儿PCBs暴露时采集产后21-210 天的母乳样本更具有代表性。
    哺乳期不同时间段母乳中PCBs 浓度水平变化趋势并不一致,而呈多样化。47%(25 位)志愿母亲母乳中PCBs 浓度随哺乳时间的延长总体表现为下降的趋势,17%(9 位)母亲母乳中PCBs 浓度表现为上升趋势; 6%(3 位)志愿母亲母乳中PCBs 浓度在整个哺乳期保持相对稳定;30%(16 位)母亲连续母乳中PCBs 浓度呈现出降中有升、总体下降的趋势。这样的研究结果提示我们,哺乳期母乳PCBs 浓度并一定随哺乳时间的延长而不断下降。某些潜在的因子可能主导哺乳期不同时间段母乳中PCBs 浓度的变化趋势。
    哺乳期母亲体重的变化对PCBs 浓度变化相关性的研究结果表明,哺乳期母亲体重变化百分比与CB-153 浓度变化百分比呈现显著负相关性,这说明母亲体重的改变很可能导致母乳中PCBs 浓度发生相应的变化。体重下降可导致体内脂质减少, PCBs 从脂肪组织中释放出来进入母乳,造成母乳中PCBs 浓度的上升。
    我们的研究结果为哺乳期母乳中POPs 的变化趋势及相关影响因子提供了基础数据,为如何减少婴/幼儿POPs 暴露风险,如何科学喂养提供了理论依据。
英文摘要:     The PCBs levels in breast milk samples collected from two typical e-waste recycling areas (Luqiao and Wenling) in Taizhou, Zhejiang Province, were examined.Further, the change of PCBs concentration in consecutive breast milk samples during lactation was studied. Besides, the potential influence factor, body weight change,related with concentration change was also explored in this study.
    The median concentrations of total PCBs in human milk found in mothers from Luqiao (n=27) and Wenling (n=48), and mothers (n=15) who have resided in Taizhou less than 5 years, were 195 ng·g-1 lipid weight (lw),98.4 ng·g-1 lw and 32.0 ng·g-1 lw, respectively. PCBs levels in human milk of mothers from Luqiao and Wenling were significantly higher than those with residential time in Taizhou <5years (p<0.001), and were also well above the background levels of Zhejiang Province and China. CB-118, CB-153 and CB-138 were the top three most abundant PCBs congeners, similar to the congener profiles of PCBs in the foodstuffs collected from Taizhou. Estimated daily intake (EDI) of PCBs for one month breast-fed infants from Luqiao and Wenling, was close to or slightly over the tolerable daily
intake (TDI) of PCBs for adults recommended by Health Canada, Environmental Health Directorate, suggesting a high exposure risk of breast-fed infants to PCBs in these two areas.
    As for all of human milk samples collected during the whole lactation, the variation range of PCBs concentrations was less than 80% during 1-210 days postpartum. Hence, if ideal sampling time suggested by WHO is not available, it was suitable to collected the breast milk samples during 1-210 days postpartum roughly to assess the exposure risk of POPs in humans. Although PCBs concentrations were insignificantly different in breast milk samples collected from 22-210 days, those in 1-7d breast milk samples were significantly higher than 8-20 days and 21-210 days breast milk. This result indicated that PCBs concentration in breast milk could be affected by the sampling time. Furthermore, to assess the exposure risk of PCBs to mothers or breast-fed infants, it should be more representative to collect the breast milk samples after 21-210 days postpartum.
    During lactation, the change of PCBs concentrations in consecutive human milk sample kept diversity. With the lactation time increasing, PCBs levels in human milk from 47% donors (n=25) showed declining, those from 17% (n=9) showed increasing, those from 6% (n=3) kept constant and those from 30% (n=16) showed declining generally with increasing levels at some points. This result indicated that PCBs concentrations did not always decline during the course of lactation, which is opposite to the traditional wisdom.
    Significant negative correlation was found between the change of maternal body weights and CB-153 levels, suggesting that body weight change may be a vital factor affecting PCBs concentrations during lactation. When body weight loss happens, the fat mass loses with it as well. The PCBs stored in the lost fat mass may be released, resulting in the increasing PCBs concentrations in human milk correspondingly.
    The study on the change of PCBs concentration in consecutive breast milk samples during lactation, and the potential influence factors related with concentration change, supplied the data support about how to reduce the exposure risk of POPs to mother/breast-fed infants.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/34352
Appears in Collections:环境化学与生态毒理学国家重点实验室_学位论文

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Recommended Citation:
吕全霞. 典型电子垃圾循环区母乳中多氯联苯(PCBs) 污染及浓度 变化趋势[D]. 北京. 中国科学院研究生院. 2015.
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