Pesticide exposure and cortical brain activation among farmworkers in Costa Rica

Mora, A. M. and Baker, J. M. and Hyland, C. and Rodriguez-Zamora, M. G. and Rojas-Valverde, D. and Winkler, M. S. and Staudacher, P. and Palzes, V. A. and Gutierrez-Vargas, R. and Lindh, C. and Reiss, A. L. and Eskenazi, B. and Fuhrimann, S. and Sagiv, S. K.. (2022) Pesticide exposure and cortical brain activation among farmworkers in Costa Rica. Neurotoxicology, 93. pp. 200-210.

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BACKGROUND: Previous epidemiological studies have reported associations of pesticide exposure with poor cognitive function and behavioral problems. However, these findings have relied primarily on neuropsychological assessments. Questions remain about the neurobiological effects of pesticide exposure, specifically where in the brain pesticides exert their effects and whether compensatory mechanisms in the brain may have masked pesticide-related associations in studies that relied purely on neuropsychological measures. METHODS: We conducted a functional neuroimaging study in 48 farmworkers from Zarcero County, Costa Rica, in 2016. We measured concentrations of 13 insecticide, fungicide, or herbicide metabolites or parent compounds in urine samples collected during two study visits (approximately 3-5 weeks apart). We assessed cortical brain activation in the prefrontal cortex during tasks of working memory, attention, and cognitive flexibility using functional near-infrared spectroscopy (fNIRS). We estimated associations of pesticide exposure with cortical brain activation using multivariable linear regression models adjusted for age and education level. RESULTS: We found that higher concentrations of insecticide metabolites were associated with reduced activation in the prefrontal cortex during a working memory task. For example, 3,5,6-trichloro-2-pyridinol (TCPy; a metabolite of the organophosphate chlorpyrifos) was associated with reduced activation in the left dorsolateral prefrontal cortex (beta = -2.3; 95% CI: -3.9, -0.7 per two-fold increase in TCPy). Similarly, 3-phenoxybenzoic acid (3-PBA; a metabolite of pyrethroid insecticides) was associated with bilateral reduced activation in the dorsolateral prefrontal cortices (beta = -3.1; 95% CI: -5.0, -1.2 and -2.3; 95% CI: -4.5, -0.2 per two-fold increase in 3-PBA for left and right cortices, respectively). These associations were similar, though weaker, for the attention and cognitive flexibility tasks. We observed null associations of fungicide and herbicide biomarker concentrations with cortical brain activation during the three tasks that were administered. CONCLUSION: Our findings suggest that organophosphate and pyrethroid insecticides may impact cortical brain activation in the prefrontal cortex - neural dynamics that could potentially underlie previously reported associations with cognitive and behavioral function. Furthermore, our study demonstrates the feasibility and utility of fNIRS in epidemiological field studies.
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH)
UniBasel Contributors:Winkler, Mirko and Fuhrimann, Samuel
Item Type:Article, refereed
Article Subtype:Research Article
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:27 Dec 2022 12:57
Deposited On:27 Dec 2022 12:57

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