Environmental health - The paradox of lead poisoning prevention
Environmental health - The paradox of lead poisoning prevention
复制标题
DOI：
10.1126/science.281.5383.1617
复制
发表时间：
1998-09-11
期刊：
影响因子：
56.9
通讯作者：
Lanphear, BP
中科院分区：
文献类型：
--
作者：
Lanphear, BP
亚临床铅中毒，定义为血铅水平为10μg/dl或更高，估计在美国每20名儿童中就有1名受到影响(1)。大多数研究表明，低水平的铅暴露对大脑功能具有严重的有害和不可逆转的影响，如智力下降和学习成绩下降，特别是发生在生命早期的暴露；还观察到听力障碍和生长迟缓(2)。总而言之，这些研究的结果认为，预防与铅暴露相关的神经认知损害的努力应该强调初级预防--在儿童过度暴露之前消除住宅中的铅危害。矛盾的是，这与目前几乎完全依赖二级预防努力的做法和政策形成了鲜明对比--只有在儿童过度暴露于铅的情况下，才试图减少儿童暴露在住宅中的铅危害。此外，尽管有大量关于如何防止铅暴露于住宅危害的建议，但很少有数据表明这些建议的控制措施对血铅水平低于25μg/dl的儿童的安全性或益处。尽管铅导致其毒性影响的机制尚不清楚，但在减少广泛的铅暴露方面已取得实质性进展。1970年以前，铅中毒的定义是血铅水平超过60μg/dl，这一水平通常与急性症状性疾病有关，包括腹部绞痛、坦率的贫血、脑病或死亡。从那时起，定义血铅水平升高的门槛逐渐降低。1991年，疾病控制中心进一步降低了门槛，降至10μg/dl(4)。在过去的二十年里，美国儿童的平均血铅水平下降了90%以上，这主要是由于汽油和饮食来源(主要是来自含铅罐头的食品和饮料)消除了铅(5)。目前，据估计，美国有890,000名学龄前儿童(4.4%)的血铅水平达到或超过10μg/dl(1)。在一些城市，特别是在美国东北部，超过35%的学龄前儿童因接触住宅铅危害而导致血铅水平超过10μg/dl(6)。
Subclinical lead toxicity, defined as a blood lead level of 10 μg/dl or higher, is estimated to affect 1 in every 20 children in the United States (1). The preponderance of studies demonstrate that low-level lead exposure has serious deleterious and irreversible effects on brain function, such as lowered intelligence and diminished school performance, especially from exposures that occur in early life; hearing deficits and growth retardation have also been observed (2). Collectively, the results of these studies argue that efforts to prevent neurocognitive impairment associated with lead exposure should emphasize primary prevention—the elimination of residential lead hazards before a child is unduly exposed. This contrasts, paradoxically, with current practices and policies that rely almost exclusively on secondary prevention efforts—attempts to reduce a child's exposure to residential lead hazards only after a child has been unduly exposed. Furthermore, despite an abundance of recommendations about how to prevent lead exposure from residential hazards, there is a paucity of data demonstrating the safety or benefits of these recommended controls for children with blood lead levels below 25 μg/dl (3).Although the mechanisms by which lead causes its toxic effects remain unknown, substantial progress has been made in reducing widespread lead exposure. Before 1970, lead poisoning was defined by blood lead levels greater than 60 μg/dl, a level often associated with acute symptomatic disease, including abdominal colic, frank anemia, encephalopathy, or death. Since then, the threshold for defining elevated blood lead levels has gradually been reduced. In 1991, the Centers for Disease Control (CDC) reduced the threshold even further, to 10 μg/dl (4). During the past two decades, average blood lead levels in US children have fallen by over 90%, largely as a result of the elimination of lead from gasoline and dietary sources (primarily foods and beverages from lead-soldered cans)(5). It is currently estimated that 890,000 (4.4%) preschool children in the United States have a blood lead level of 10 μg/dl or higher (1). In some cities, especially in the northeastern United States, more than 35% of preschool children have blood lead levels exceeding 10 μg/dl from exposure to residential lead hazards (6).