Neurobehavioral function and low-level metal exposure in adolescents.

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.

Trace metals in blood and urine of newborn/mother pairs, adolescents and adults of the Flemish population (2007-2011).

The Flemish Centre for Environment and Health started with human biomonitoring in 2002 (FLEHS I: 2002-2006). The main goal of the second human biomonitoring cycle (FLEHS II: 2007-2011), was to determine mean values for a large number of pollutants in a representative sample of the general Flemish population. Values for Cd and Pb were updated, and a group of previously undetermined metals and metalloids (As, Mn, Cu and Tl) were included in some of the age groups. In this human biomonitoring program, three different age groups of the general Flemish population were monitored: 255 newborns and their mothers, 210 adolescents aged 14-15, and 204 adults between 20 and 40 years old. Trace elements were determined in cord blood and maternal blood of the mothers, in blood and urine of adolescents and in urine of adults. Determinants of life-style and personal factors were taken into account. The levels of trace elements in cord blood and maternal blood were for most elements at the lower end of the range found in literature. For Pb, As and Tl, a strong correlation (respectively r=0.43, 0.55 and 0.33; p<0.05) was found between levels in cord blood (respectively 8.6, 0.54 and 0.017 µg/L) and maternal blood (11.1, 0.64 and 0.028 µg/L), indicating that they are transported via the placenta from mother to fetus. The levels found in the adolescents and adults were compared with results from international biomonitoring studies, and were found to be in the same ranges. With the exception of Pb, all trace elements increased with increasing age group population. Finally, the results also showed that the levels of Cd and Pb in blood for this campaign (e.g. for Pb 8.6 and 14.8 µg/L in neonates and adolescents respectively) were lower compared to the first campaign (e.g. for Pb 14.7 and 21.7 µg/L in neonates and adolescents respectively), indicating a decrease over time. However, differences in sampling strategies might partially explain this observed trend.

Trace metal concentrations measured in blood and urine of adolescents in Flanders, Belgium: reference population and case studies Genk-Zuid and Menen.

In the Flemish human biomonitoring programme FLEHS II (2007-2011) trace metals (Cd, Pb, Cr, Ni, Cu, Mn, Tl, Sb, As and toxic relevant arsenic) were analysed in the blood and urine of adolescents (14-15 years old) in the reference population in Flanders and in areas of important industrial activities: Genk-Zuid and Menen. After adjustment of the results for confounding factors, the adolescents living in Genk-Zuid had higher levels of Cr, Cu and Tl in blood, higher levels of Cd and toxic relevant arsenic (TRA) in urine, but lower levels of Ni in blood and Sb in urine compared to the reference population. In Menen higher levels of Cd and Cu in urine, higher concentrations of Tl in blood but lower concentrations of Pb in blood and lower Ni, Sb and As in urine were found compared to the reference population. For both the reference population and the hot spots the concentrations are within the ranges found in other countries. Compared to the previous biomonitoring programme FLEHS I (2002-2006) a decrease in the concentrations of Cd and especially of Pb in blood was observed. However, it cannot be excluded that differences between the two campaigns are partially due to different sampling strategies.

Concept of the Flemish human biomonitoring programme.

Since 2002 a human biomonitoring network has been established in Flanders (Belgium) as part of a programme on environmental health surveillance. The human biomonitoring network should support environmental health policy by identifying priorities for further action. The first cycle of the programme (2002-2006) confirmed the hypotheses that living in areas with different environmental pressure is reflected in different loads of environmental chemicals in the residents. In the second cycle of the programme (2007-2011) the number of environmental chemicals for which human biomonitoring data were obtained was expanded substantially. The goal of the Flemish programme is to use and translate the scientific results into policy actions. Its further orientation in the second cycle to human biomonitoring in hot spots and sensitive age groups or susceptible persons with underlying complications (e.g. persons with diabetes) are linked to these goals. Interaction with stakeholders is embedded in the programme emphasizing transparency of the choices that are made and direct communication. The Flemish human biomonitoring programme is organized centrally with major involvement of research partners from different disciplines which allows engrafting environmental health research on the programme. One of the major focuses is the question whether combinations of pollutants in the general population are associated with biological effects. The objective of this paper is to review and discuss the options that were taken in the human biomonitoring programme in order to achieve its goals.