Washington State Department of Health, Olympia, WA, USA.
Environ Health. 2012 Jun 7;11:37. doi: 10.1186/1476-069X-11-37.
The most prominent non-occupational source of exposure to methylmercury is the consumption of fish. In this study we examine a fish consuming population to determine the extent of temporal exposure and investigate the extent to which single time estimates of methylmercury exposure based on blood-Hg concentration can provide reliable estimates of longer-term average exposure.
Blood-mercury levels were obtained from a portion of the Arsenic Mercury Intake Biometric Study (AMIBS) cohort. Specifically, 56 Japanese women residing in the Puget Sound area of Washington State, US were sampled on three occasions across a one-year period.
An average of 135 days separated samples, with mean blood-mercury levels for the visits being 5.1, 6.6 and 5.0 μg/l and geometric means being 2.7, 4.5 and 3.1 μg/l. The blood-mercury levels in this group exceed national averages with geometric means for two of the visits being between the 90th and 95th percentiles of nationally observed levels and the lowest geometric mean being between the 75th and 90th percentile. Group means were not significantly different across sampling periods suggesting that exposure of combined subjects remained relatively constant. Comparing intra-individual results over time did not reveal a strong correlation among visits (r = 0.19, 0.50, 0.63 between 1st and 2nd, 2nd and 3rd, and 1st and 3rd sample results, respectively). In comparing blood-mercury levels across two sampling interval combinations (1st and 2nd, 2nd and 3rd, and 1st and 3rd visits, respectively), 58% (n = 34), 53% (n = 31) and 29% (n = 17) of the individuals had at least a 100% difference in blood-Hg levels.
Point estimates of blood-mercury, when compared with three sample averages, may not reflect temporal variability and individual exposures estimated on the basis of single blood samples should be treated with caution as indicators of long-term exposure. Reliance on single blood samples can make predicting ongoing methylmercury exposure highly speculative due to the large intra-individual variability.
非职业性甲基汞暴露的最主要来源是食用鱼类。本研究旨在调查一个鱼类消费人群，以确定其暴露时间的长短，并探讨基于血液汞浓度的单次暴露估计值在多大程度上可以提供长期平均暴露的可靠估计。
从砷汞摄入生物计量研究（AMIBS）队列中获取部分血液汞水平数据。具体来说，美国华盛顿州普吉特海湾地区的 56 名日本女性在一年期间的三个时间点进行了采样。
两次采样平均间隔 135 天，三次访问的平均血液汞水平分别为 5.1、6.6 和 5.0μg/L，几何平均值分别为 2.7、4.5 和 3.1μg/L。该组血液汞水平高于全国平均水平，两次访问的几何平均值处于全国观察水平的第 90 至 95 百分位之间，最低几何平均值处于第 75 至 90 百分位之间。各采样期间组均值无显著差异，提示联合受试者的暴露相对稳定。比较个体随时间的内个体结果发现，各次访问之间相关性不强（第 1 次和第 2 次、第 2 次和第 3 次、第 1 次和第 3 次样本结果的相关系数分别为 0.19、0.50 和 0.63）。比较两种采样间隔组合（第 1 次和第 2 次、第 2 次和第 3 次、第 1 次和第 3 次访问）的血液汞水平，58%（n=34）、53%（n=31）和 29%（n=17）的个体血液-Hg 水平差异至少为 100%。
与三次采样平均值相比，血液汞的点估计值可能无法反映时间变化，基于单次血液样本估计的个体暴露值应谨慎使用，作为长期暴露的指标。由于个体内变异性较大，仅依赖单次血液样本预测甲基汞的持续暴露具有高度推测性。
