Department of Epidemiology and Environmental Health, School of Public Health and Health Professions, The State University of New York, Buffalo, New York 14214, United States.
Research and Education in Energy, Environment and Water Institute, University at Buffalo, Buffalo, New York 14260, United States.
Chem Res Toxicol. 2020 Nov 16;33(11):2699-2718. doi: 10.1021/acs.chemrestox.0c00167. Epub 2020 Oct 12.
Autism spectrum disorder (ASD) is a complex neurobehavioral disorder that is believed to be multifactorial in origin. As the incidence of ASD is rising along with industrialization, and because certain metals have been linked to neurological problems, it is important to consider whether such metals may play a role in the development of ASD. Previously, we performed a meta-analysis of existing literature to examine the potential link between inorganic arsenic and lead exposure and ASD. This is a continuation of that study investigating the association of the exposure to aluminum (Al), cadmium (Cd), and mercury (Hg) and ASD. These metals were chosen because they are abundant in our environment, are known to cause neurological problems in humans, and have multiple published studies examining their potential links with ASD. Following the same approach as our previous paper, we conducted a systematic review of the existing literature and performed a meta-analysis to evaluate the current evidence regarding these metals and their potential relationship with autism. We reviewed 18 studies on Al, 18 on Cd, and 23 on Hg, and the individual studies showed inconsistent results. When the measurements were integrated into the meta-analysis, we found significant associations between all the metals and ASD, but the associations were not always in the same direction. Levels of Hg in hair, urine, and blood were all positively associated with ASD. Levels of Al in hair and urine were positively associated with ASD, while levels of Al in blood were negatively associated. In comparison, levels of Cd in hair and urine were negatively associated with ASD. These results imply that, while these metals are all neurotoxic, their impact on the development of ASD and their modes of action could be different. Further research is warranted to examine the longitudinal effects of these toxic metals on the risk of ASD, to assess the critical period when exposure may affect development, and to investigate potential factors that may enhance or ameliorate the effect of metals. Overall, these findings support policies that advocate limiting exposure to neurotoxic metals, particularly for pregnant women and young children, in order to help reduce the rising incidence of ASD.
自闭症谱系障碍（ASD）是一种复杂的神经行为障碍，据信其起源是多因素的。随着工业化的发展，ASD 的发病率不断上升，而且某些金属已被证明与神经问题有关，因此，有必要考虑这些金属是否可能在 ASD 的发展中发挥作用。此前，我们对现有文献进行了荟萃分析，以研究无机砷和铅暴露与 ASD 之间的潜在联系。本研究是对之前研究的延续，旨在探讨铝（Al）、镉（Cd）和汞（Hg）暴露与 ASD 之间的关联。选择这些金属是因为它们在我们的环境中含量丰富，已知会对人类造成神经问题，并且有多项已发表的研究探讨了它们与 ASD 的潜在关联。我们采用与之前论文相同的方法，对现有文献进行了系统综述，并进行了荟萃分析，以评估这些金属及其与自闭症的潜在关系的现有证据。我们对 18 项关于 Al 的研究、18 项关于 Cd 的研究和 23 项关于 Hg 的研究进行了综述，个别研究结果不一致。当将这些测量值整合到荟萃分析中时，我们发现所有金属与 ASD 之间均存在显著关联，但关联方向并不总是相同。头发、尿液和血液中的 Hg 水平均与 ASD 呈正相关。头发和尿液中的 Al 水平与 ASD 呈正相关，而血液中的 Al 水平与 ASD 呈负相关。相比之下，头发和尿液中的 Cd 水平与 ASD 呈负相关。这些结果表明，虽然这些金属都是神经毒性的，但它们对 ASD 发展的影响及其作用模式可能不同。需要进一步的研究来检测这些有毒金属对 ASD 风险的纵向影响，评估可能影响发育的关键时期，并研究可能增强或减轻金属影响的潜在因素。总的来说，这些发现支持了限制孕妇和幼儿接触神经毒性金属的政策，以帮助降低 ASD 发病率的上升。
