Poorer cognitive function and environmental airborne Mn exposure determined by biomonitoring and personal environmental monitors in a healthy adult population

Andrea Expósito,María García-Martínez,Bohdana Markiv,Laura Ruiz-Azcona,Ana Pozueta,Ignacio Fernández-Olmo,Miguel Santibáñez

doi:10.1016/j.scitotenv.2022.152940

Abstract

Background/aimIn the Santander Bay (Cantabria, northern Spain), a ferromanganese alloy plant is located. Our objective was to characterize the Mn personal exposure of adult healthy volunteers living in this highly Mn exposed region, and to determine its association with a poorer cognitive function. MethodsCross-sectional study analyzing 130 consecutive participants. Cognitive function was assessed by Stroop Color Word, Verbal Fluency tests, Trail Making Test (TMT), Digit Span (WAIS III) and Rey Osterrieth Complex Figure (ROCF) tests and crude scores were standardized according to NEURONORMA norms. Exposure to Mn was assessed in terms of source distance, by Personal Environmental Monitors (PEMs) allowing the separation of fine (PM2.5) and coarse (PM10–2.5) particles (obtaining the bioaccessible fraction by in-vitro bioaccessibility tests), and by biomarkers (blood, hair and fingernails). Age, sex, study level and number of years of residence were predefined as confounding variables and adjusted Mean Differences (MDs) were obtained. ResultsStatistically significant lower scores (negative MDs) in all test were observed when living near the industrial emission source, after adjusting for the predefined variables. Regarding PEMs results, statistically significant lower scores in all Stroop parts were obtained in participants with higher levels of Total Mn in All fractions (PM10). For Verbal Fluency tests, negative MDs were obtained for both bioaccessible fractions. Digit Span Backward scores were lower for those with higher levels in the bioaccessible coarse fraction, and negative MDs were also observed for the ROCF Delayed part and the non-bioaccessible fine fraction. As regards to Mn in fingernails, adjusted MDs of −1.60; 95%CI (−2.57 to −0.64) and −1.45; 95%CI (−2.29 to −0.61) for Digit Span Forward and Backward parts were observed. ConclusionsOur results support an association between poorer cognitive function and environmental airborne Mn exposure.

Highlights

Neurological and neuropsychological negative health effects have been described in relation to high levels of occupational Manganese (Mn) (Bowler et al, 2006a, 2006b; Dlamini et al, 2020; Lucchini et al, 1999; Mergler et al, 1994; Roels et al, 1987; Williams et al, 2012), even though it is an essential trace element found in the human body (Chen et al, 2018)
The area of study (Santander Bay, Cantabria, northern Spain) has been described elsewhere (Arruti et al, 2010, 2011a, 2011b; Hernández-Pellón and Fernández-Olmo, 2019a, 2019b). Those living in the town of Maliaño within a radio of approximately 1.5 km from the industrial emission sources (IES) were considered as the highly exposed group; whereas those living in the city of Santander located between 5 and 10 km from the same IES, were considered as moderately-exposed
Mn fingernail levels, and to a lesser extent Mn hair levels, were associated with poorer cognitive function according to this test

Summary

Introduction

Neurological and neuropsychological negative health effects have been described in relation to high levels of occupational Manganese (Mn) (Bowler et al, 2006a, 2006b; Dlamini et al, 2020; Lucchini et al, 1999; Mergler et al, 1994; Roels et al, 1987; Williams et al, 2012), even though it is an essential trace element found in the human body (Chen et al, 2018). Blood (Bowler et al, 2012; Lucchini et al, 2014), scalp and axillary hair (Viana et al, 2014), urine (Lucchini et al, 2014) and fingernails and saliva (Viana et al, 2014) have been used in the published studies with different results (Bauer et al, 2020a; Fernández-Olmo et al, 2021; Haynes et al, 2015; Ntihabose et al, 2018; Viana et al, 2014)

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