International Journal of Hygiene and Environmental Health 218 (2015) 139–146 Contents lists available at ScienceDirect International Journal of Hygiene and Environmental Health jo u r n al homepage: www.elsevier.com/locate/ijheh Neurobehavioral function and low-level metal exposure in adolescents Michal Kicinski a , Jan Vrijens b , Griet Vermier c , Elly Den Hond d , Greet Schoeters d,e , Vera Nelen f , Liesbeth Bruckers g , Isabelle Sioen h , Willy Baeyens b , Nicolas Van Larebeke b,i , Mineke K. Viaene j , Tim S. Nawrot a,k,∗ a Centre for Environmental Sciences, Hasselt University, Diepenbeek, Belgium b Department of Analytical and Environmental Chemistry, Vrije Universiteit Brussel (VUB), Brussel, Belgium c Integrated Psychiatric Centre OPZ Geel, Geel, Belgium d Flemish Institute for Technological Research, Environmental Risk and Health, Mol, Belgium e Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium f Department of Health, Provincial Institute for Hygiene, Antwerp, Belgium g Interuniversity Institute for Biostatistics and Statistical Bioinformatics, Hasselt University, Diepenbeek, Belgium h Department of Public Health, Ghent University, Ghent, Belgium i Department of Radiotherapy and Nuclear Medicine, Ghent University, Ghent, Belgium j Department of Neurology, Sint Dimphna Hospital, Geel, Belgium k School of Public Health and Primary Care, KU Leuven, Leuven, Belgium a r t i c l e i n f o Article history: Received 11 March 2014 Received in revised form 15 September 2014 Accepted 16 September 2014 Keywords: Adolescents Cognition Copper Lead Metals Neurotoxicity a b s t r a c t An excessive metal exposure is harmful to the brain. However, many aspects of metal neurotoxicity remain unclear including the magnitude of the low-level exposure effects and the level of exposure that can be assumed safe. The aim of our study was to investigate the association between a low-level metal exposure and three neurobehavioral domains (sustained attention, short-term memory, and manual motor speed). We measured Cd, Cu, Mn, Pb, and Tl in blood, Cd, Ni, and toxicologically relevant As in urine and methyl Hg in hair in 606 adolescents between 13.6 and 17 years of age. A two-fold increase in blood Cu was associated with a 0.37 standard deviations decrease in sustained attention (95% CI: −0.67 to −0.07, p = 0.02) and 0.39 standard deviations decrease in short-term memory (95% CI: −0.70 to −0.07, p = 0.02), accounting for gender, age, smoking, passive smoking, household income per capita, occupation of the parents, and education level of the mother. None of the other metals was significantly associated with the neurobehavioral domains that were measured. The observed associations between blood Cu and neurobehavioral performance are in line with recent studies in elderly. However, the relevance of our results for public health remains to be elucidated. © 2014 Elsevier GmbH. All rights reserved. Introduction Excessive exposure to metals has a strong neurotoxic poten- tial. Transition metals copper, manganese, and mercury catalyze redox reactions. Heavy metals lead and cadmium and a metalloid arsenic bind to proteins and interfere with metal transport and pro- tein function and are also capable of inducing oxidative toxicity (Wright and Baccarelli, 2007). Exposure to toxic metals may have ∗ Corresponding author at: Hasselt University, Centre for Environmental Sciences, Agoralaan gebouw D, Diepenbeek, 3590 Hasselt, Belgium. Tel.: +32 11 268382; fax: +32 11 268299. E-mail address: tim.nawrot@uhasselt.be (T.S. Nawrot). serious public health consequences because contaminants such as lead, mercury, and arsenic are widespread. Forty years of epidemio- logical research has demonstrated that a lead exposure is associated with impaired cognitive function in children (Landrigan et al., 1975; Lidsky and Schneider, 2003; Pocock et al., 1994). There is a growing amount of evidence that lead exposure resulting in blood lead lev- els lower than 10 g/dL may affect cognitive performance (Gilbert and Weiss, 2006; Jusko et al., 2007; Lanphear et al., 2005). This raises the issue of changing the current safety threshold (Gilbert and Weiss, 2006). However, it is currently unclear what levels of lead exposure can be assumed safe (ATSDR, 2007; CDC, 2005). A high methylmercury exposure has disastrous consequences for the brain, as evidenced by cases of methylmercury poison- ing (Amin-zaki et al., 1978; Harada et al., 2001; Karada, 1978; http://dx.doi.org/10.1016/j.ijheh.2014.09.002 1438-4639/© 2014 Elsevier GmbH. All rights reserved.