Institute for Quantitative Biomedical Sciences, Dartmouth College, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA.
Environ Health. 2013 Feb 5;12:13. doi: 10.1186/1476-069X-12-13.
Low-level environmental cadmium exposure and neurotoxicity has not been well studied in adults. Our goal was to evaluate associations between neurocognitive exam scores and a biomarker of cumulative cadmium exposure among adults in the Third National Health and Nutrition Examination Survey (NHANES III).
NHANES III is a nationally representative cross-sectional survey of the U.S. population conducted between 1988 and 1994. We analyzed data from a subset of participants, age 20-59, who participated in a computer-based neurocognitive evaluation. There were four outcome measures: the Simple Reaction Time Test (SRTT: visual motor speed), the Symbol Digit Substitution Test (SDST: attention/perception), the Serial Digit Learning Test (SDLT) trials-to-criterion, and the SDLT total-error-score (SDLT-tests: learning recall/short-term memory). We fit multivariable-adjusted models to estimate associations between urinary cadmium concentrations and test scores.
5662 participants underwent neurocognitive screening, and 5572 (98%) of these had a urinary cadmium level available. Prior to multivariable-adjustment, higher urinary cadmium concentration was associated with worse performance in each of the 4 outcomes. After multivariable-adjustment most of these relationships were not significant, and age was the most influential variable in reducing the association magnitudes. However among never-smokers with no known occupational cadmium exposure the relationship between urinary cadmium and SDST score (attention/perception) was significant: a 1 μg/L increase in urinary cadmium corresponded to a 1.93% (95%CI: 0.05, 3.81) decrement in performance.
These results suggest that higher cumulative cadmium exposure in adults may be related to subtly decreased performance in tasks requiring attention and perception, particularly among those adults whose cadmium exposure is primarily though diet (no smoking or work based cadmium exposure). This association was observed among exposure levels that have been considered to be without adverse effects and these levels are common in U.S. adults. Thus further research into the potential neurocognitive effects of cadmium exposure is warranted. Because cumulative cadmium exposure may mediate some of the effects of age and smoking on cognition, adjusting for these variables may result in the underestimation of associations with cumulative cadmium exposure. Prospective studies that include never-smokers and non-occupationally exposed individuals are needed to clarify these issues.
低水平环境镉暴露和神经毒性在成年人中尚未得到充分研究。我们的目标是评估第三国家健康和营养检查调查（NHANES III）中成年人神经认知考试成绩与累积镉暴露生物标志物之间的关联。
NHANES III 是一项针对美国人口的全国代表性横断面调查，于 1988 年至 1994 年进行。我们分析了一组年龄在 20-59 岁之间的参与者的数据，他们参加了计算机化的神经认知评估。有四个结果衡量标准：简单反应时间测试（SRTT：视觉运动速度）、符号数字替代测试（SDST：注意力/感知）、连续数字学习测试（SDLT）试验到标准和 SDLT 总错误分数（SDLT-测试：学习回忆/短期记忆）。我们拟合了多变量调整模型，以估计尿镉浓度与测试分数之间的关联。
5662 名参与者接受了神经认知筛查，其中 5572 名（98%）有尿镉水平。在多变量调整之前，较高的尿镉浓度与 4 项结果中的每一项表现较差相关。在多变量调整后，这些关系大多数不再显著，年龄是降低关联幅度的最具影响力的变量。然而，在没有已知职业镉暴露的从不吸烟者中，尿镉与 SDST 分数（注意力/感知）之间的关系是显著的：尿镉增加 1μg/L 对应于表现下降 1.93%（95%CI：0.05，3.81）。
这些结果表明，成年人中累积镉暴露较高可能与需要注意力和感知的任务中表现略有下降有关，特别是在那些镉暴露主要通过饮食（不吸烟或工作相关镉暴露）的成年人中。在被认为没有不良影响的暴露水平下观察到这种关联，而这些水平在美国成年人中很常见。因此，有必要进一步研究镉暴露对认知的潜在神经认知影响。由于累积镉暴露可能会影响年龄和吸烟对认知的一些影响，因此调整这些变量可能会导致对累积镉暴露的关联的低估。需要进行包括从不吸烟者和非职业暴露者在内的前瞻性研究，以澄清这些问题。
