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Manganese exposure and working memory-related brain activity in smallholder farmworkers in Costa Rica : results from a pilot study

Palzes, Vanessa A. and Sagiv, Sharon K. and Baker, Joseph M. and Rojas-Valverde, Daniel and Gutiérrez-Vargas, Randall and Winkler, Mirko S. and Fuhrimann, Samuel and Staudacher, Philipp and Menezes-Filho, José A. and Reiss, Allan L. and Eskenazi, Brenda and Mora, Ana M.. (2019) Manganese exposure and working memory-related brain activity in smallholder farmworkers in Costa Rica : results from a pilot study. Environmental research, 173. pp. 539-548.

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Official URL: https://edoc.unibas.ch/70290/

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Abstract

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.
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH)
09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Department of Epidemiology and Public Health (EPH) > Eco System Health Sciences > Health Impact Assessment (Utzinger)
UniBasel Contributors:Winkler, Mirko
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:Elsevier
ISSN:0013-9351
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:25 Apr 2019 08:37
Deposited On:25 Apr 2019 08:37

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