即使低水平砷暴露也与心血管疾病相关

对强心研究(Strong Heart Study)数据的一项分析显示，即使暴露于饮食和水中低至中度水平的无机砷也与心血管疾病发病率和死亡率相关。该结果在线发表于9月24日的《内科学年鉴》(Annals of Internal Medicine)杂志。

长期以来，公认环境高砷水平与心血管疾病风险增高相关，目前，来自一项大型前瞻性心脏研究的数据次要分析显示，即使是美国农村社区中常见的低水平砷暴露也与心血管风险呈强相关关系，并且这种相关性呈现剂量依赖性模式。


Katherine A. Moon

巴尔的摩市约翰霍普金斯大学Bloomberg公共卫生学院环境科学系的Katherine A. Moon女士及其合作者使用来自强心研究的数据，对这一相关性进行了评估，这是一项在亚利桑那州、俄克拉荷马州和达科他州农村的3个美洲土著社区中进行的一项以人群为基础的心血管疾病队列研究。为了进行分析，Moon女士及其同事对1989~1991年间入选的3,575例无心血管疾病的男性和女性的储存尿液样品中的砷浓度进行了测定。研究受试者基线时年龄为45~75岁，对其随访心血管结局17~19年。

结果显示，在随访期间，共有1,184例受试者发生心血管疾病，共发生846起冠心病事件和264起脑卒中事件。共有439例受试者死于心血管疾病，包括341例死于冠心病，54例死于脑卒中。分析显示，基线时尿液中的砷浓度与心血管疾病的发生相关。与尿液中砷浓度最低的男性和女性相比，砷浓度处于最高四分位间距的人群更易于发生心血管疾病［风险率(HR)为1.32］、冠心病(HR，1.30)和脑卒中(HR，1.47)。

基线时尿液中的砷浓度也与心血管死亡率相关。与尿液中砷浓度最低的男性和女性相比，砷浓度处于最高四分位间距的人群更易死于心血管疾病［HR，1.65］、冠心病(HR，1.71)或脑卒中(HR，3.03)。在经校正社会人口统计学因素、吸烟状况和血脂水平等对数据的影响之后，这些相关性依然存在。而尿液中砷甜菜碱的浓度与心血管结局无相关性，砷甜菜碱是一种有机砷，主要见于海水中，被认为无毒性。

在患有糖尿病的男性和女性中，砷浓度与心血管风险之间的相关性最强，这是之前的砷暴露研究中从未评估过的一个亚组人群。研究者表示，对于这一结果，“需要慎重解释和在其他人群中进行重复验证”。

该研究由国立心肺血液研究所和国立环境卫生科学研究所资助。研究者未披露存在任何利益冲突。

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By: MARY ANN MOON, Cardiology News Digital Network

Even low to moderate levels of exposure to inorganic arsenic in food and water correlate with cardiovascular disease incidence and mortality, according to an analysis of the Strong Heart Study.

The results were published online Sept. 24 in Annals of Internal Medicine.

High environmental arsenic levels have long been recognized as correlating with higher risk of cardiovascular disease, but a secondary analysis of data from a large prospective heart study now shows that even at low levels commonly found in rural communities across the United States, arsenic exposure is strongly related to cardiovascular risk and mortality in a dose-dependent fashion.

"These findings support the importance of low to moderate arsenic exposure as a cardiovascular risk factor with no apparent threshold," said Katherine A. Moon of the department of environmental sciences, Johns Hopkins University Bloomberg School of Public Health, Baltimore, and her associates.

They assessed this correlation using data from the Strong Heart Study, a population-based cohort study of cardiovascular disease in three Native American communities in rural Arizona, Oklahoma, and the Dakotas. For their analysis, Ms. Moon and her colleagues measured arsenic species concentrations in stored urine samples from 3,575 men and women with no cardiovascular disease at enrollment during 1989-1991.

These study subjects, aged 45-75 years at baseline, were followed for cardiovascular outcomes for 17-19 years.

A total of 1,184 subjects developed cardiovascular disease during follow-up, with 846 incident coronary heart disease events and 264 incident strokes. A total of 439 subjects died from cardiovascular disease, including 341 who died from coronary heart disease and 54 who died from stroke.

Urinary arsenic concentrations at baseline correlated with the development of cardiovascular disease. Compared with men and women who had the lowest arsenic levels, those in the highest quartile were more likely to develop cardiovascular disease (hazard ratio 1.32), coronary heart disease (HR 1.30), and stroke (HR 1.47).

Urinary arsenic levels at baseline also correlated with cardiovascular mortality. Compared with men and women who had the lowest levels, those in the highest quartile were more likely to die from cardiovascular disease (hazard ratio, 1.65), coronary heart disease (HR, 1.71), or stroke (HR, 3.03).

These associations persisted after the data were adjusted to account for the effects of sociodemographic factors, smoking status, and lipid levels.

In contrast, urinary levels of arsenobetaine, an organic arsenical that is found chiefly in seafood and is thought to be nontoxic, showed no associations with cardiovascular outcomes.

Overall, these findings provide "important novel data in a Western population with high background cardiovascular risk," Ms. Moon and her associates noted.

The association between arsenic levels and cardiovascular risk was strongest among men and women who had diabetes, a subgroup of the population that has not been evaluated in previous studies of arsenic exposure. This finding "needs to be interpreted cautiously and requires replication in other populations," the researchers said.

The Environmental Protection Agency has estimated that 13 million Americans are chronically exposed to arsenic in drinking water, and many millions more are exposed to arsenic in food. It is possible that mitigating these exposures could reduce the burden of cardiovascular disease in the United States and across the globe, they added.

This study was supported by the National Heart, Lung, and Blood Institute and the National Institute of Environmental Health Sciences. No financial conflicts of interest were reported.