Manganese exposure and working memory-related brain activity in smallholder farmworkers in Costa Rica: Results from a pilot study.
Manganese exposure and working memory-related brain activity in smallholder farmworkers in Costa Rica: Results from a pilot study.
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DOI：
10.1016/j.envres.2019.04.006
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发表时间：
2019-06
影响因子：
8.3
通讯作者：
Vanessa A. Palzes;S. Sagiv;J. M. Baker;Daniel Rojas-Valverde;R. Gutiérrez-Vargas;Mirko S. Winkler;S. Fuhrimann;P. Staudacher;J. Menezes-Filho;A. Reiss;B. Eskenazi;A. Mora
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文献类型：
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作者：
Vanessa A. Palzes;S. Sagiv;J. M. Baker;Daniel Rojas-Valverde;R. Gutiérrez-Vargas;Mirko S. Winkler;S. Fuhrimann;P. Staudacher;J. Menezes-Filho;A. Reiss;B. Eskenazi;A. Mora
一般人群中锰（Mn）的主要来源是饮食和饮用水。锰也存在于农业中使用的双二硫代氨基甲酸乙酯（EBDC）杀菌剂中，或由锰铁工厂排放到空气中的杀菌剂和焊接烟雾中，这可能是额外的环境和职业暴露源。高职业锰暴露与运动、行为和认知障碍有关，但其对神经功能的影响尚不清楚。我们对哥斯达黎加扎塞罗县48名农场工人进行了功能神经成像研究，这是一个喷洒EBDC杀菌剂的农业区。我们测量了农场工人脚趾甲（n= 40名农场工人）和头发（n= 33名农场工人）中的Mn浓度，并使用功能近红外光谱（fNIRS）记录了在字母检索工作记忆任务期间背外侧前额叶皮层的大脑活动。我们使用调整了年龄和教育水平的多变量线性回归模型估计暴露与结果的关联。脚趾甲和毛发锰浓度几何平均值（几何标准差）分别为0.40 μg（3.52）和0.24 μg/g（3.54）。在这个农场工人样本中，我们没有发现强有力的证据表明锰浓度与工作记忆相关的大脑活动有关；我们还发现工作记忆任务准确性和大脑活动之间没有关联。然而，我们的小样本量可能限制了我们以统计精度检测小效应大小的能力。我们的研究表明，在环境流行病学中，fNIRS可以作为一种有用和可行的工具，用于检查有毒物质（如Mn）对神经功能的影响。这可能被证明是重要的阐明神经病理途径的基础上，先前报道的升高的锰暴露与神经毒性作用的关联。
Main sources of manganese (Mn) in the general population are diet and drinking water. Mn is also found in ethylene bisdithiocarbamate (EBDC) fungicides used in agriculture or emitted into the air by ferromanganese plants and welding fumes, which can be additional environmental and occupational sources of exposure. High occupational Mn exposure has been linked with motor, behavioral, and cognitive impairment, but its effects on neural function remain poorly understood. We conducted a functional neuroimaging study in a sample of 48 farmworkers in Zarcero County, Costa Rica, an agricultural region where EBDC fungicides are sprayed. We measured Mn concentrations in farmworkers’ toenails (n= 40 farmworkers) and hair (n= 33 farmworkers), and recorded brain activity in the dorsolateral prefrontal cortex during a letter-retrieval working memory task using functional near-infrared spectroscopy (fNIRS). We estimated exposure-outcome associations using multivariable linear regression models adjusted for age and education level. Geometric mean (geometric standard deviation) toenail and hair Mn concentrations were 0.40 μg/g (3.52) and 0.24 μg/g (3.54), respectively. We did not find strong evidence that Mn concentrations were associated with working memory-related brain activity in this sample of farmworkers; we also found null associations between working memory task accuracy and brain activity. However, our small sample size may have limited our ability to detect small effect sizes with statistical precision. Our study demonstrates that fNIRS can be a useful and feasible tool in environmental epidemiology for examining the effects of toxicants, like Mn, on neural function. This may prove to be important for elucidating neuropathological pathways that underlie previously reported associations of elevated Mn exposure with neurotoxic effects.