Shaffer Rachel M, Wright J Michael, Cote Ila, Bateson Thomas F
Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC, USA.
Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH, USA.
Environ Res. 2023 Mar 15;221:115319. doi: 10.1016/j.envres.2023.115319. Epub 2023 Jan 17.
Manganese (Mn) is neurotoxic in adults and children. Current assessments are based on the more extensive adult epidemiological data, but the potential for greater childhood susceptibility remains a concern. To better understand potential lifestage-based variations, we compared susceptibilities to neurotoxicity in children and adults using Mn biomarker data.
We developed a literature search strategy based on a Population, Exposures, Comparators, and Outcomes statement focusing on inhalation exposures and neurological outcomes in humans. Screening was performed using DistillerSR. Hair biomarker studies were selected for evaluation because studies with air measurements were unavailable or considered inadequate for children. Studies were paired based on concordant Mn source, biomarker, and outcome. Comparisons were made based on reported dose-response slopes (children vs. adults). Study evaluation was conducted to understand the confidence in our comparisons.
We identified five studies evaluating seven pairings of hair Mn and neurological outcomes (cognition and motor effects) in children and adults matched on sources of environmental Mn inhalation exposure. Two Brazilian studies of children and one of adults reported intelligent quotient (IQ) effects; effects in both comparisons were stronger in children (1.21 to 2.03-fold difference). In paired analyses of children and adults from the United States, children exhibited both stronger and weaker effects compared to adults (0.37 to 1.75-fold differences) on postural sway metrics.
There is limited information on the comparative susceptibility of children and adults to inhaled Mn. We report that children may be 0.37 to 2.03 times as susceptible as adults to neurotoxic effects of Mn, thereby providing a quantitative estimate for some aspects of lifestage variation. Due to the limited number of paired studies available in the literature, this quantitative estimate should be interpreted with caution. Our analyses do not account for other sources of inter-individual variation. Additional studies of Mn-exposed children with direct air concentration measurements would improve the evidence base.
锰（Mn）对成人和儿童具有神经毒性。目前的评估基于更广泛的成人流行病学数据，但儿童更高易感性的可能性仍然令人担忧。为了更好地理解基于生命阶段的潜在差异，我们使用锰生物标志物数据比较了儿童和成人对神经毒性的易感性。
我们基于关注人类吸入暴露和神经学结果的人群、暴露、对照和结果声明制定了文献检索策略。使用DistillerSR进行筛选。选择头发生物标志物研究进行评估，因为没有空气测量研究或认为这些研究对儿童不充分。根据一致的锰来源、生物标志物和结果对研究进行配对。根据报告的剂量反应斜率（儿童与成人）进行比较。进行研究评估以了解我们比较的可信度。
我们确定了五项评估儿童和成人七组头发锰与神经学结果（认知和运动影响）配对的研究，这些配对在环境锰吸入暴露源上相匹配。两项巴西儿童研究和一项成人研究报告了智商影响；在两项比较中，儿童的影响更强（差异为1.21至2.03倍）。在美国儿童和成人的配对分析中，与成人相比，儿童在姿势摇摆指标上表现出更强和更弱的影响（差异为0.37至1.75倍）。
关于儿童和成人对吸入锰的比较易感性的信息有限。我们报告儿童对锰神经毒性作用的易感性可能是成人的0.37至2.03倍，从而为生命阶段差异的某些方面提供了定量估计。由于文献中可用的配对研究数量有限，应谨慎解释此定量估计。我们的分析未考虑个体间变异的其他来源。对直接测量空气浓度的锰暴露儿童进行更多研究会改善证据基础。
