Spitzer W O, Baxter D W, Barrows H S, Thomas D C, Tamblyn R, Wolfson C M, Dinsdale H B, Dauphinee W D, Anderson D P, Roberts R S
Montreal General Hospital Research Institute, McGill University, Quebec.
Clin Invest Med. 1988 Apr;11(2):71-98.
We conducted a cross-sectional epidemiologic and clinical study to evaluate the nature, magnitude, and frequency of unfavourable health states among residents of northwest Quebec. Of particular interest were the possible occurrence of Minamata disease and any other neurological abnormalities. We also sought to determine whether industrial or naturally-occurring mercury in the region's environment were causally associated with any disorders that might be detected. A total of 321 subjects were studied in four groups with contrasting exposure to point-source mercury from a chlor-alkali plant in the area. Methylmercury in hair served as the marker of subject's ingestion of any organic mercury (natural or industrial). Ten pre-chosen target variables, seven clinical and three neurophysiological, were assessed in all subjects. Relationships between mercury in hair and each target variable were calculated. We determined whether gradients in target variables corresponded to gradients in potential exposure of the subjects to the aquatic emissions of the chlor-alkali plant. Minamata disease was not found. Diabetes and alcohol-related health problems assessed as important clinically plausible confounders, were common. Differences in frequency or magnitude of clinical, toxicological, and physiological findings among the contrast groups were small and not of clinical or statistical significance. There were definite relationships between mercury in hair and four target variables despite the low values of mercury measured and the mild nature of the health problems observed. This would suggest that verifiable biological threshold levels for clinical effects, if such exist, may be substantially lower among Canadians than those currently adopted as policy for adults elsewhere. A gradient was found only for two of the ten target variables. Clinically meaningful alternate hypotheses for observed health effects emerge in the data and agree with observations in the field made by consulting clinical experts.
我们开展了一项横断面流行病学和临床研究，以评估魁北克西北部居民中不良健康状况的性质、程度和频率。特别令人感兴趣的是水俣病以及任何其他神经异常情况的可能发生。我们还试图确定该地区环境中的工业汞或天然汞是否与可能检测到的任何疾病存在因果关系。共有321名受试者被分为四组，这四组受试者接触该地区一家氯碱厂点源汞的情况各不相同。头发中的甲基汞作为受试者摄入任何有机汞（天然或工业来源）的标志物。对所有受试者评估了十个预先选定的目标变量，其中七个是临床变量，三个是神经生理学变量。计算了头发中的汞与每个目标变量之间的关系。我们确定目标变量的梯度是否与受试者接触氯碱厂水生排放物的潜在暴露梯度相对应。未发现水俣病。糖尿病和与酒精相关的健康问题被评估为临床上重要的潜在混杂因素，较为常见。各对比组在临床、毒理学和生理学结果的频率或程度上差异较小，无临床或统计学意义。尽管所测汞值较低且观察到的健康问题性质较轻，但头发中的汞与四个目标变量之间存在明确关系。这表明，如果存在临床效应的可验证生物阈值水平，加拿大人的该阈值可能比目前其他地方成人所采用的政策阈值要低得多。在十个目标变量中，仅发现两个存在梯度。数据中出现了对观察到的健康效应具有临床意义的替代假设，且与咨询临床专家后在该领域的观察结果一致。
