Balbus-Kornfeld J M, Stewart W, Bolla K I, Schwartz B S
Department of Environmental Health Sciences, Johns Hopkins School of Hygiene and Public Health, Baltimore, Maryland 21205, USA.
Occup Environ Med. 1995 Jan;52(1):2-12. doi: 10.1136/oem.52.1.2.
To evaluate the current evidence that cumulative exposure to inorganic lead is associated with decreased performance in neurobehavioural tests in adults.
21 unique studies were reviewed from 28 published manuscripts. An algorithm was developed to determine the usefulness of each study on the basis of exposure assessment, control of confounding variables, methods of subject selection, test conditions, and data analysis. Highest emphasis was placed on the use of cumulative measures of exposure or absorption.
Only three studies used a measure of cumulative exposure to or absorption of lead, and two others used duration of exposure as a surrogate for cumulative exposure. All other studies used a measure that did not adequately estimate cumulative exposure to lead, most often current blood lead concentration. 20 of the studies controlled for age as a confounding variable, although in several studies the possibility for residual confounding by age remained. 16 studies controlled for intellectual ability before exposure; all of them used educational level for this purpose. Of the five studies that used direct or surrogate measures of cumulative exposure to or absorption of lead, two were thought to be of low usefulness because of inadequate duration of exposure. The three remaining studies found stronger associations of neurobehavioural performance with recent exposure measures than with those of cumulative exposure.
The current scientific literature provides inadequate evidence to conclude whether or not cumulative exposure to or absorption of lead adversely affects performance in neurobehavioural tests in adults. The current evidence is flawed because of inadequate estimation of cumulative exposure to or absorption of lead and inadequate control for age and intellectual ability before exposure.
评估目前关于成年人累积接触无机铅与神经行为测试表现下降相关的证据。
从28篇已发表的手稿中筛选出21项独特的研究。开发了一种算法，根据暴露评估、混杂变量控制、受试者选择方法、测试条件和数据分析来确定每项研究的有用性。最强调使用累积暴露或吸收量度。
只有三项研究使用了铅累积暴露或吸收的量度，另外两项研究使用暴露持续时间作为累积暴露的替代指标。所有其他研究使用的量度均不能充分估计铅的累积暴露，最常见的是当前血铅浓度。20项研究将年龄作为混杂变量进行了控制，尽管在一些研究中年龄残留混杂的可能性仍然存在。16项研究在暴露前对智力能力进行了控制；所有这些研究都为此目的使用了教育水平。在五项使用铅累积暴露或吸收的直接或替代量度的研究中，两项因暴露持续时间不足而被认为有用性较低。其余三项研究发现，神经行为表现与近期暴露量度的关联比与累积暴露量度的关联更强。
目前的科学文献提供的证据不足，无法得出累积接触或吸收铅是否会对成年人神经行为测试表现产生不利影响的结论。目前的证据存在缺陷，因为对铅累积暴露或吸收的估计不足，以及对年龄和暴露前智力能力的控制不足。
