Department of Environmental Health Sciences, Tohoku University Graduate School of Medicine, 2-1 Seiryo-machi, Sendai 980-8575, Japan.
Neurotoxicol Teratol. 2010 Mar-Apr;32(2):240-5. doi: 10.1016/j.ntt.2009.08.009. Epub 2009 Sep 2.
To scrutinize whether the provisional tolerable weekly intake (PTWI, 3.4 microg/kg body weight/week) of methylmercury in Japan is safe for adults, we conducted an intervention study using heart rate variability (HRV) that has been considered to reflect cardiac events. Fifty-four healthy volunteers were recruited and divided into experimental and control groups. The experimental group was exposed to methylmercury at the PTWI level through consumption of bigeye tuna and swordfish for 14 weeks, and HRV parameters were compared between the two groups. In the experimental group, mean hair mercury levels, determined before and after the dietary methylmercury exposure and after 15-week wash-out period following the cessation of exposure, were 2.30, 8.76 and 4.90 microg/g, respectively. The sympathovagal balance index of HRV was significantly elevated after the exposure, and decreased to the baseline level at the end of this study. Still, such changes in HRV parameters were not found in the control group with a mean hair mercury level of around 2.1 microg/g. In conclusion, the PTWI does not appear to be safe for adult health, because methylmercury exposure from fish consumption induced a temporary sympathodominant state. Rather, long-term exposure to methylmercury may pose a potential risk for cardiac events involving sympathovagal imbalance among fish-consuming populations.
为了探究日本暂定每周可耐受摄入量（PTWI，3.4μg/kg 体重/周）的甲基汞对成年人是否安全，我们进行了一项干预研究，使用了被认为能反映心脏事件的心率变异性（HRV）。我们招募了 54 名健康志愿者，并将其分为实验组和对照组。实验组通过食用大眼金枪鱼和箭鱼，在 14 周内接触甲基汞，达到 PTWI 水平，比较两组的 HRV 参数。在实验组中，在膳食甲基汞暴露前后以及暴露停止后 15 周的洗脱期内，平均头发汞水平分别为 2.30、8.76 和 4.90μg/g。HRV 的交感神经-迷走神经平衡指数在暴露后显著升高，在研究结束时降至基线水平。然而，对照组的 HRV 参数没有发生变化，对照组的平均头发汞水平约为 2.1μg/g。总之，PTWI 似乎对成年人的健康不安全，因为鱼类消费导致的甲基汞暴露会引起暂时的交感优势状态。相反，长期暴露于甲基汞可能对食用鱼类人群的交感神经-迷走神经失衡引起的心脏事件构成潜在风险。
