Valera Beatriz, Dewailly Eric, Poirier Paul
Public Health Research Unit, 2875 Boulevard Laurier, Edifice Delta 2, bureau 600, G1V 2M2, Quebec (Qc), Canada.
Environ Health. 2008 Jun 6;7:29. doi: 10.1186/1476-069X-7-29.
Mercury is a contaminant that reaches high levels in Nunavik (North of Quebec). It is transformed into methylmercury (MeHg) and accumulated in marine mammals and predator fish, an important part of the traditional Inuit diet. MeHg has been suggested to affect BP in adults and children while the influence on HRV has only been studied in children. We aimed to assess the impact of MeHg levels on HRV and BP in Inuit adults from Nunavik.
In the fall of 2004, the <<Qanuippitaa?>> Health Survey was conducted in Nunavik (Quebec, Canada) and information on HRV was collected among 280 adults aged 40 years and older. Indicators of the time and frequency domains of HRV were derived from a 2-hour Holter recording. BP was measured according to the Canadian Coalition for High Blood Pressure technique. Pulse pressure (PP) was the difference between systolic (SBP) and diastolic blood pressure (DBP). Blood mercury concentration was used as exposure biomarker. Statistical analysis was conducted through linear regression and multivariable linear regression was used to control for confounders.
Mercury was negatively correlated with low frequency (LF) (r = -0.18; p = 0.02), the standard deviation of RR intervals (SDNN) (r = -0.14; p = 0.047) and the coefficient of variation of RR intervals (CVRR) (r = -0.18; p = 0.011) while correlations with other HRV parameters did not reach statistical significance. After adjusting for confounders, the association with LF (beta = -0.006; p = 0.93) became non significant. However, the association with SDANN became statistically significant (beta = -0.086; p = 0.026) and CVRR tended to decrease with blood mercury concentrations (beta = -0.057; p = 0.056). Mercury was positively correlated with SBP (r = 0.25; p < 0.0001) and PP (r = 0.33; p < 0.0001). After adjusting for confounders, these associations remained statistically significant (beta SBP = 4.77; p = 0.01 and beta PP = 3.40; p = 0.0036). Moreover, most of the HRV parameters correlated well with BP although SBP the best before adjustment for mercury exposure.
The results of this study suggest a deleterious impact of mercury on BP and HRV in adults. SBP and PP increased with blood mercury concentrations while SDANN decreased with blood mercury concentrations.
汞是一种污染物，在努纳维克（魁北克北部）达到很高的水平。它会转化为甲基汞（MeHg）并在海洋哺乳动物和食肉鱼类中蓄积，而这些是因纽特人传统饮食的重要组成部分。有研究表明，MeHg会影响成人和儿童的血压，而对心率变异性（HRV）的影响仅在儿童中进行过研究。我们旨在评估MeHg水平对努纳维克因纽特成年人HRV和血压的影响。
2004年秋季，在加拿大魁北克省努纳维克开展了“Qanuippitaa?”健康调查，收集了280名40岁及以上成年人的HRV信息。HRV的时域和频域指标来自2小时的动态心电图记录。血压按照加拿大高血压联盟技术进行测量。脉压（PP）为收缩压（SBP）与舒张压（DBP）之差。血液汞浓度用作暴露生物标志物。通过线性回归进行统计分析，并使用多变量线性回归控制混杂因素。
汞与低频（LF）呈负相关（r = -0.18；p = 0.02）、RR间期标准差（SDNN）呈负相关（r = -0.14；p = 0.047）以及RR间期变异系数（CVRR）呈负相关（r = -0.18；p = 0.011），而与其他HRV参数的相关性未达到统计学显著性。在对混杂因素进行调整后，与LF的关联（β = -0.006；p = 0.93）变得不显著。然而，与SDANN的关联变得具有统计学显著性（β = -0.086；p = 0.026）并且CVRR随血液汞浓度有下降趋势（β = -0.057；p = 0.056）。汞与SBP呈正相关（r = 得统计学显著性（βSBP = 4.77；p = 0.01且βPP = 3.40；p = 0.0036）。此外，尽管在调整汞暴露之前SBP与大多数HRV参数的相关性最佳，但大多数HRV参数与血压的相关性良好。
本研究结果表明汞对成年人的血压和HRV有有害影响。SBP和PP随血液汞浓度升高而增加，而SDANN随血液汞浓度降低。 0.25；p < 0.0001）以及PP呈正相关（r = 0.33；p < 0.0001）。在对混杂因素进行调整后，这些关联仍具
