Association between methylmercury exposure from fish consumption and child development at five and a half years of age in the Seychelles Child Development Study: An evaluation of nonlinear relationships
Association between methylmercury exposure from fish consumption and child development at five and a half years of age in the Seychelles Child Development Study: An evaluation of nonlinear relationships
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DOI：
10.1006/enrs.2000.4082
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发表时间：
2000-10-01
影响因子：
8.3
通讯作者：
Clarkson, TW
中科院分区：
文献类型：
--
作者：
Axtell, CD;Cox, C;Clarkson, TW
迄今为止，使用线性回归模型进行分析的塞舌尔群岛产前和产后甲基汞暴露对塞舌尔群岛鱼类发育影响的研究尚未显示出对神经发育测试分数的不利影响。在这项研究中，我们使用对塞舌尔儿童发展研究中 66 个月大的队列儿童进行的六项测试的分数来评估甲基汞暴露是否存在非线性效应，通过测量代表怀孕期间生长的母亲头皮头发中的汞来确定产前暴露。产后暴露量是通过在孩子 1 个月大时采集的一段头发来测量的。分析中使用了广义加性模型（GAM），该模型不对暴露与测试分数之间关系的函数形式做出任何假设。类似于原始线性回归模型的 GAM 用于重新分析 66 个月测试组的六个主要发育终点。在产前暴露与学前语言量表 (PLS) 总分和儿童行为检查表 (CBCL) 之间以及产后暴露与麦卡锡一般认知指数 (GCI) 测试分数之间的关系中发现了小的非线性。这些影响最好以图形方式描述，但可以通过计算预测测试分数从 0 到 10 或 15 ppm 以及高于此点的变化来总结。对于 PLS，趋势是在 0 到 10 ppm 之间下降 0.8 个点，然后在 10 ppm 以上增加（代表改进）1.3 个点。对于 CBCL，从 0 到 15 ppm 增加了 1 个点，然后在 15 ppm 以上下降（改善）4 个点。 GCI 在 10 ppm 之前增加了 1.8 个点，然后在 10 ppm 以上下降了 3.2 个点（代表性能更差）。这些结果并不完全一致。其中两个趋势涉及产前暴露的有益影响。一种可能的不利趋势涉及产后暴露。在每种情况下，趋势都会改变方向，因此一个方向的影响之后会出现相反方向的影响。由于 GAM 的描述性，很难为估计趋势提供精确的统计显着性水平。当然，高于 10 ppm 的数据较少，并且高于此水平的趋势的估计精度较低。总体而言，没有明确的证据表明暴露对六种发育结果具有一致的（在整个暴露水平范围内）不利影响。对这些数据进行进一步的非线性建模可能是合适的，但也存在在没有明确生物学原理的情况下拟合复杂模型的风险，(C) 2000 学术出版社。
Studies to date of the developmental effects of pre- and postnatal methylmercury exposure from fish consumption in the Seychelles Islands, using linear regression models for analysis, have not shown adverse effects on neurodevelopmental test scores. In this study we evaluated whether nonlinear effects of methylmercury exposure were present, using scores on six tests administered to cohort children in the Seychelles Child Development Study at 66 months of age, Prenatal exposure was determined by measuring mercury in a segment of maternal scalp hair representing growth during pregnancy. Postnatal exposure was measured in a segment of the child's hair taken at ge-months of age. Generalized additive models (GAMs), which make no assumptions about the functional form of the relationship between exposure and test score, were used in the analysis. GAMs similar to the original linear regression models were used to reanalyze the six primary developmental endpoints from the 66-month test battery. Small nonlinearities were identified in the relationships between prenatal exposure and the Preschool Language Scale (PLS) Total score and Child Behavior Check List (CBCL) and between postnatal exposure and the McCarthy General Cognitive Index (GCI) test scores, The effects are best described graphically but can be summarized by computing the change in the predicted test score from 0 to either 10 or 15 ppm and then above this point. For the PLS the trend involved a decline of 0.8 points between 0 and 10 ppm followed by an increase (representing improvement) of 1.3 points above 10 ppm. For the CBCL there was an increase of 1 point from 0 to 15 ppm, and then a decline (improvement) of 4 points above 15 ppm. The GCI increased by 1.8 points through 10 ppm and then declined 3.2 points (representing worse performance) above 10 ppm. These results are not entirely consistent. Two of the trends involve what appear to be beneficial effects of prenatal exposure. The one possibly adverse trend involves postnatal exposure. In every case the trend changes direction, so that an effect in one direction is followed by an effect in the opposite direction. Because of the descriptive nature of GAMs it is difficult to provide a precise level of statistical significance for the estimated trends. Certainly above 10 ppm there is less data and trends above this level are estimated less precisely. Overall there was no clear evidence for consistent (across the entire range of exposure levels) adverse effects of exposure on the six developmental outcomes. Further nonlinear modeling of these data may be appropriate, but there is also the risk of fitting complex models without a clear biological rationale, (C) 2000 Academic Press.