Academic journal article Environmental Health Perspectives

Prenatal Mancozeb Exposure, Excess Manganese, and Neurodevelopment at 1 Year of Age in the Infants' Environmental Health (ISA) Study

Academic journal article Environmental Health Perspectives

Prenatal Mancozeb Exposure, Excess Manganese, and Neurodevelopment at 1 Year of Age in the Infants' Environmental Health (ISA) Study

Article excerpt

Introduction

Manganese (Mn) ethylene bis-dithiocarbamate (EBDC) fungicides, such as mancozeb and maneb, are widely used in agriculture and professional turf management (U.S. EPA 2005). EBDCs contain approximately 21% Mn by weight (FAO 1980), and recent studies suggest that their use may constitute a source for elevated ethylene-thiourea (ETU) (van Wendel de Joode et al. 2014), EBDCs' main metabolite, and Mn (Gunier et al. 2013; Mora et al. 2014; van Wendel de Joode et al. 2016a) in agricultural communities. Naturally occurring Mn in groundwater may also be a source of excess Mn for these communities, whose water supply is mainly from artesian wells (van Wendel de Joode et al. 2016a).

Animal studies have shown that early-life exposure to Mn-containing fungicides and/or to ETU impairs neurodevelopment (Jacobsen et al. 2012; Miranda-Contreras et al. 2005). However, the few epidemiological studies that have examined this association in children have found inconsistent results (Gunier et al. 2015; Mora et al. 2015; van Wendel de Joode et al. 2016b). A cross-sectional study of children 6-9 y old living near banana and plantain plantations in Talamanca County, Costa Rica, observed that higher urinary ETU concentrations were associated with poorer verbal learning outcomes (van Wendel de Joode et al. 2016b). In addition, a study from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) that measured Mn in deciduous teeth from children living near agricultural fields in the Salinas Valley, California, reported an association between higher postnatal dentin Mn levels and decreased mental development scores on the Bayley Scales of Infant Development, 2nd Edition (BSID-II) at 6 and 12 mo of age, but not at 24 mo of age (Gunier et al. 2015). Another study within CHAMACOS found associations of higher prenatal and postnatal dentin Mn levels with poorer behavioral outcomes in school-age boys and girls (7-10.5 y old), but better cognitive, memory, and/or motor function abilities in boys (Mora et al. 2015).

Multiple prospective and cross-sectional studies have assessed the neurodevelopmental effects of excess Mn from sources other than Mn-containing fungicides. Most of these studies have consistently linked exposure to airborne or waterborne Mn with impaired cognitive abilities (Bouchard et al. 2011; Carvalho et al. 2014; do Nascimento et al. 2016; Haynes et al. 2015; Kim et al. 2009; Menezes-Filho et al. 2011; Rahman et al. 2017; Riojas-Rodriguez et al. 2010; Wasserman et al. 2006; Wright et al. 2006), behavioral problems (Bouchard et al. 2007; Khan et al. 2012; Menezes-Filho et al. 2014; Oulhote et al. 2014a; Rahman et al. 2017), and poor memory outcomes (Carvalho et al. 2014; He et al. 1994; Hernandez-Bonilla et al. 2011; Lucchini et al. 2012a; Oulhote et al. 2014a) in school-age children, adolescents, or in both. Findings from studies in infants have not been as consistent as those conducted in older children. For example, prenatal Mn exposure has been associated with impaired mental, psychomotor, and/or language skills at 1 and 2 y of age (Claus Henn et al. 2017; Lin et al. 2013; Yu et al. 2016); and with poorer behavior (Ericson et al. 2007) and nonverbal memory at 3 y of age (Takser et al. 2003). Some studies have also reported inverted U-shaped associations of prenatal or early postnatal Mn exposure with BSID-II mental and/or psychomotor developmental scores at 6 mo (Chung et al. 2015) and at 1 y (Claus Henn et al. 2010), and with Bayley Scales of Infant Development, 3rd edition (BSID-III) fine motor scores at 2-3 y of age (Rodrigues et al. 2016).

The Infants' Environmental Health Study (Infantes y Salud Ambiental, ISA) is a community-based birth cohort study examining the health effects of pesticides and Mn in pregnant women and their children living near banana plantations with extensive aerial spraying of Mn-containing fungicides (Bravo Duran et al. 2013) in Matina County, Costa Rica. …

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