Uehara Ritei, Peng Guan, Nakamura Yosikazu, Matsuura Nobuo, Kondo Naomi, Tada Hiroshi
Department of Public Health, Jichi Medical School, 3311-1 Yakushiji, Minamikawachi, Tochigi 329-0498, Japan.
Chemosphere. 2006 Feb;62(7):1135-41. doi: 10.1016/j.chemosphere.2005.05.049. Epub 2005 Aug 9.
Much attention has been paid to the level of dioxins in breast milk in Japan but few large-scale studies have been conducted on the subject.
From 1997 to 2002, we collected 839 samples of breast milk from primiparas residing throughout Japan. Starting in 1999, breast milk was also collected from secundiparas. Seven isomers of polychlorinated dibenzo-p-dioxins (PCDDs), 10 of polychlorinated dibenzofurans (PCDFs), 4 of coplanar polychlorinated biphenyls (Co-PCBs) and 8 of mono-orthochlorinated polychlorinated biphenyls (mono-ortho PCBs) were analyzed by employing gas chromatography and mass spectrometry. A correlation between the level of dioxins in human milk and the age of the mothers was noted for the primiparas and the secundiparas; and the levels were compared between the first and the second deliveries. Grouped by parity and prefecture in each year, observations were also made on the trends in these levels. Dioxin levels are shown by using geometric means because their distributions were skewed to the left.
The sum of PCDDs and PCDFs, Co-PCBs, mono-ortho PCBs, and total dioxins in the breast milk of primiparas were 13.9, 5.4, 3.4, and 22.7 pg TEQ/g fat, respectively. In the samples obtained from secundiparas, these levels were 63-68 percents of those taken from the primiparas. The correlation coefficients between the PCDDs/DFs, Co-PCBs, mono-ortho PCBs, and total dioxins and the age of the primiparas were 0.19, 0.17, 0.36, and 0.24, respectively. All these correlations were statistically significant (p < 0.001). The positive correlations between these contaminants and the age of the secundiparas were also examined. The total dioxins as well as PCDDs/DFs, Co-PCBs, and mono-ortho PCBs in the breast milk of the primiparas declined significantly between 1998 and 2002 (regression coefficients: -0.04, -0.05, -0.03, and -0.03, respectively). However, no significant decline in these levels was observed when sorted by prefectures.
Much attention should be paid to the age and parity of nursing mothers when investigating the relationship between the level of dioxins in breast milk and the body burden of infants.
日本对母乳中二恶英水平给予了高度关注，但针对该主题的大规模研究较少。
1997年至2002年，我们收集了来自日本各地初产妇的839份母乳样本。从1999年开始，也收集经产妇的母乳。采用气相色谱和质谱法分析了7种多氯二苯并对二恶英（PCDDs）异构体、10种多氯二苯并呋喃（PCDFs）异构体、4种共平面多氯联苯（Co-PCBs）和8种单邻位氯代多氯联苯（单邻位PCBs）。观察到初产妇和经产妇母乳中二恶英水平与母亲年龄之间存在相关性；并比较了首次分娩和第二次分娩时的水平。每年按产次和地区分组，还观察了这些水平的变化趋势。由于二恶英水平分布向左偏态，故采用几何平均数表示。
初产妇母乳中PCDDs和PCDFs、Co-PCBs、单邻位PCBs以及总二恶英的含量分别为13.9、5.4、3.4和22.7 pg TEQ/g脂肪。在经产妇的样本中，这些水平是初产妇样本的63 - 68%。PCDDs/DFs、Co-PCBs、单邻位PCBs以及总二恶英与初产妇年龄的相关系数分别为0.19、0.17、0.36和0.24。所有这些相关性均具有统计学意义（p < 0.001）。还研究了这些污染物与经产妇年龄之间的正相关性。1998年至2002年期间，初产妇母乳中的总二恶英以及PCDDs/DFs、Co-PCBs和单邻位PCBs显著下降（回归系数分别为：-0.04、-0.05、-0.03和-0.03）。然而，按地区分类时未观察到这些水平有显著下降。
在研究母乳中二恶英水平与婴儿体内负担之间的关系时，应高度关注哺乳母亲的年龄和产次。
