Trace metals analyses in the general Flemish population and in the hot spots Gent-Zuid en Menen

Abstract

During the second half of the 20th century, awareness rose about the consequences of industrial evolution and the increase in the world population on the environment and public health. Today, environmental problems and their associated health risks are well established in the policy making of governmental organizations worldwide. This is also the case in Flanders, where a Human Biomonitoring program was started by the Flemish Ministry of Health in 1999. It is within the context of the second cycle of the Flemish Environment and Health Survey that this thesis covers the survey of trace metal in whole blood and urine of neonates and their mothers, adolescents and adults.
Various trace metals were determined with the use of high resolution inductively coupled plasma mass spectrometry. Prior to analyses, acid digestion methods were applied to destroy the organic matrix of the whole blood and urine samples. The optimization and validation of the used methods lead to the development of routine analysis procedures allowing the measurement of large quantities of samples necessary for biomonitoring. Existing reference values for the Flemish population for Cd and Pb in whole blood, obtained during the first cycle of the Flemish Human Biomonitoring program, were updated while reference values in blood and/or urine of neonates, adolescents and adults were established for a group of previously undetermined metals (Cr, Ni, As, TRA, Mn, Cu, Tl and Sb).
Although a declining trend in trace metal pollution is observed during the last decades, trace metal exposure remains of importance due to possible health risks for the general population. Two industrialized areas, Genk-Zuid and Menen, were selected via an open hot spot procedure to test whether differences in levels of exposure could be detected through biomonitoring studies. Therefore, trace metal levels in whole blood and urine of adolescents residing in these areas were compared with the reference values obtained for the Flemish population. Exposure to toxic substances can, however, be influenced by different personal and life-style factors such as age, gender, smoking, dietary habits and socio-economic status. These influencing parameters were taken into account by using multiple linear regression models. After correction for influencing factors, living in Genk-Zuid was associated with a significantly higher exposure to Cd (18% higher in urine), Cr (32% higher in blood), Cu (5% higher in blood, 11% higher in urine), Tl (11% higher in blood) and As (toxic relevant arsenic 32% higher in urine). On the other hand, significantly lower concentrations were observed for Sb (21% lower in urine) and Ni (7% lower in urine). Living in the area of Menen was associated with significantly higher exposure to Tl (27% higher in blood and 14% higher in urine), Cu (6% higher in blood) and Cd (28% higher in urine) but lower values were observed in Menen for Pb (11% lower in blood), Ni (25% lower in urine), Sb (25% lower in urine) and As (20% lower in urine).
The observed trace metal levels give an indication of the possible exposure pressure related to a certain area of living, but do not say anything about the possible associated health effects. In order to get an insight in these associations, dose-response relationships were determined between trace metals in blood/urine and effect markers reflecting growth and development, immunology, fertility and cardiovascular function. Multiple regression models were built and data on individual health and lifestyle, obtained through questionnaires, were used to correct for possible influencing factors. An important finding was the significant relationship between arsenic and the risk of being born small for gestational age and an accelerated blood platelet aggregation in adults. Blood copper was significantly associated with attention in adolescents. This correlation was inversely U-shaped, indicating that both deficiency and excess of copper can be relevant for neurobehavioral function. Also significant were some of the negative relationships between urinary/blood thallium and pubertal development parameters in boys and girls. Furthermore, urinary cadmium in adolescents was positively correlated with the percentage of DNA migration, and indicator of DNA damage, and urinary cadmium and chromium showed positive associations with urinary alpha-1-microglobuline and serum cystatin C respectively, suggesting their negative impact on kidney function.

Date of Award	31 Mar 2013
Original language	English
Supervisor	Willy Baeyens (Promotor), Martine Leermakers (Co-promotor) & Philippe Claeys (Promotor)